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A/B/O: Adventures in Fake Science.

Chapter Text

A Friendly Greeting

Hello. I see you are interested in unifying a/b/o worlds with logic. Well, I can not promise that everything herein will be utterly logical, this is a/b/o we're talking about, but I do promise that at least the process for which I arrive at conclusions will be logical. Mostly. But a good many of the behaviours, concepts, and cultural views that a/b/o tropes create can actually be explained beyond 'for porn!'. Surprising, I know.

Clearly I will be biased upon fics I've read, fics I've read the descriptions for, fics I've heard about, and fics I've wrote. But I will make best efforts to make the information within this work as generic as possible. While I have laid out in detail various things I think make the most sense I've also taken the time to present some other options as well. Of course, you can disregard everything within this work (half the fun of shared world building is giving it your own spin), but you can also flagrantly borrow from this work as well. If you like a concept or idea I fully encourage you to use it. 



Once upon a time I saw the a/b/o tag and was like " the hell is there a tag for stories about blood types?" And then I clicked on it. " not blood types." After that I was sort of 'eah' about a/b/o verses and then one day I was drinking and through a discussion on tumblr somehow (alcohol) ended up writing an a/b/o fic which started off purely as a joke and then it evolved into a story where people don't really have all that much sex (and when they do it's scary or horrible or embarrassing) which is like the anti-thesis of a/b/o fics but it made me start thinking about a/b/o verses.

So I thought about a/b/o verses and I read a bunch of a/b/o fics and started developing Opinions.

And that is what this fics is: My opinion on how a/b/o works and how it could have gotten to be the way it is (you know, besides we wrote it that way). If you decide that your opinion on how a/b/o works does not align with my opinion on how a/b/o works that's cool. This is a weird shared AU and I'm not the a/b/o AU police.


Data Collection

This work was put together by extrapolating upon tropes common in a/b/o worlds and mentions of background characters. The background characters are important because almost all fics have an alpha/omega couple as the protagonists. All those brief mentions of so and so getting married, having kids, etc actually help us to figure out what is going on not only socially in the story but also genetically and culturally.

Another thing to keep in consideration, this work was written with verses in mind that break down population to mostly betas, some alphas, and few omegas. There are other versions of a/b/o worlds (mostly alphas or sterile betas, are a few of the other versions I've seen frequently) and I will do what I can to try to bash those over the head with science too but they will mostly be covered in a few appendixes at the end.


The Contents

What will this work contain? There will be a breakdown on sex determination, I go over my preferred method in detail but in later chapters I cover some other options. There will be an explanation as to how X/Y and A/B/O sex determination actually work together instead of being decided separately. Don't forget the wild conjecture about alpha, beta, and omega anatomy and the guesswork about a/b/o evolutionary history.

Interspersed throughout you will find the occasional opinion and pitch for things I think you should totally do because they would make a/b/o a better AU. Mostly this will probably be write more female alphas with dicks but hey, who knows, sometimes I meander.


The First of Many Wild Assumptions

I'm assuming that if you've clicked on this that you are familiar with the concept of a/b/o and tropes commonly found in a/b/o fics.

If your are not familiar with any of that you are probably in for a wild and confusing ride.




Chapter Text

This is only going to explain one system of a/b/o in detail, the more prevalent: lots of betas, some alphas, and few omegas. In the appendix I'll give a run down of some alternatives that make worlds with tons of alphas, some betas, few omegas; equal amounts alphas and betas with few omegas; equal amounts alphas and omegas with few betas; and even the mythical equal 1/3 biological sex split and look at how they either fit into a/b/o worlds or don't work at all. But here we're going to cover mostly betas, some alphas, and few omegas.

I will start off by making some broad assumptions (this will be how we start off a lot of things here).

Broad Assumptions

  1. There are more betas than alphas or omegas.
  2. There are more alphas than omegas.
  3. Betas are fertile.
  4. Beta/beta sometimes produce beta children but sometimes produce alpha or omega children.
  5. Beta/alpha produce beta or alpha children but sometimes produce omega children.
  6. Alpha/alpha produce alpha children but sometimes produce omega children. They do not produce beta children.
  7. Alpha/omega produce alpha or omega children. They never produce beta children.
  8. Omega/beta is socially pressured against and provides insufficient data.
  9. Omega/omega is socially pressured against and provides insufficient data.

A Brief Note: Yes, I Am Aware

I am aware that generally speaking chromosomes are not dominant/recessive to other chromosomes and that it's genes on the chromosomes that are dominant or recessive in various complex ways. However I think it's easier to grasp the concept this way since most people probably remember their high school biology (and those lovely punnett squares) and are more familiar with the dominant/recessive terminology instead of activation/inactivation or some rambling explanation about the presence of one gene over another determining A, B, or O genotype. In short: dominant/recessive still gets the point across so I'm using it.

A Three Chromosome Model

First off, why are we disregarding a two chromosome model? Because based upon tropes in fics it wouldn't work. I'll discuss why in the appendices.

Now, getting to it! a/b/o fics generally agree alphas and omegas are skewed towards the rare side of things while betas are more numerous. If this is the case obviously sex determination is not being determined equally across all three sexes. Most fics don't appear to have 1/3 equal distribution. The worlds seem to break down into a majority of betas, a smaller number of alphas, and very few omegas (unless it's alpha world or there's some kind of crazy post apocalyptic omega breeding camp going on but that's another story).  

Most explanations I've seen for this try to account for all possible chromosome combinations resulting in live births: AA, AB, AO, BB, BO, and OO. A number of these explanations make A the dominant expression which I think would make for an interesting meta on making genetics conform to tropes. There's no reason for A to be dominant. In fact if alphas are less numerous than betas but are apparently hyper fertile freaks it doesn't make sense for the population distribution. Alphas would just mate with everyone and either get 50% alphas or 100% alphas. Where's the drama in that, right? 

From the cross section of fics I've read it would appear that beta/alpha couples can produce alpha, omega, or beta children, beta/beta couples occasionally produce alpha and omega offspring but usually have beta children, alpha/omega couples rarely, bordering never, produce beta children, and alpha/alpha couples also rarely, bordering never, have beta children and are more frequently described as having pregnancy complications.

So my conclusion, having assigned alpha, beta, omega chromosomes the obvious symbols of A, B, O with a lower case letter showing when a chromosome is not phenotypically expressed (minus behaviour) in a certain combination, is this:

  • B must actually be the dominant chromosome in all combinations: BB, aB, and oB.
  • A has to be recessive to B but dominate to O
  • OO is the only way to get an omega
  • AA must be a nonviable combination

Thus we have

  • Ao - alpha carrier for the omega chromosome
  • BB - beta
  • oB - beta carrier for the omega chromosome
  • aB - beta carrier for the alpha chromosome
  • OO - omega

How does that work out in offspring? Lets look at some punnett squares because everyone likes those, right?

(green = B chromosome, purple = A chromosome, orange = O chromosome)

bbbeta  abbeta  obbeta

omega  alpha

(numbers are rounded to the nearest 5th just to make it easier to read)

As you can see that looks like a wall of green and orange, B chromosomes and O chromosomes everywhere, and very few instances of the A chromosome. But most offspring turn out to be betas. If all things are left equal and there's no social bias or environmental pressure for who mates with who this works out to a population that's about 65% beta and 35% alpha or omega (and without social pressure there are slightly more omegas than alphas, 20% and 15% respectively). Already we've got the beta majority and no this does not mean that alphas and omegas will die out. Betas would have to go on a very aggressive eugenics campaign to not only wipe out all omegas and alphas but all betas that are recessive carriers for A and O as well. Stop reading that trash about red heads dying out.

When you break down the beta population a bit further it comes out looking like this: 30% oB beta with about 15% aB beta and 20% BB beta. This seems a little off kilter but when you look at the number of O chromosomes in play (Ao, oB, and OO) you'll notice that they're in high demand. There are just as many instances of O chromosomes as there are B chromosomes (BB, aB, and oB) but there are fewer instances of the A chromosome (Ao and aB). Alphas and omegas both rely on the O chromosome to achieve their biological sex. The two groups combined are more likely to pass on an O chromosome than anything else. So as previously said if there are no outside forces altering mate selection the O chromosome happens at the same rate as the B chromosome it's simply not expressed in in two thirds of the people who carry it.

But this gives us a world with more omegas than alphas which doesn't quite fit. However this is also a world without social bias on mate selection which definitely does not fit a/b/o fics. So what happens when social biases are applied?

A Rambling Discussion

Most fics seem to agree that omegas are more rare than alphas. Why is that? Irony essentially.

The first issue is that most fics paint a picture where culturally alpha children are considered more desirable than beta or omega children. The second issue is that the social conventions in most fics encourage omegas to only mate with alphas. Alphas may sometimes mate with betas or other alphas but again the most socially acceptable pairing is alpha/omega with alpha/alpha coming in a close second (but rarely the lead pairing of the story). As of July 8th 2015 there are 133 fics in the alpha/beta tag, 15 fics in the omega/beta tag, and 1937 fics in the alpha/omega tag (Note: the specific tag 'beta' is actually very large but mostly appears to be people tagging about beta readers). Social convention is to blame. Well. Probably porn convention since about 80% of all a/b/o fics seems to revolve around either weird sex or mpreg.

Anyway, alphas prefer omegas as mates but occasionally take alphas or betas as mates while omegas are often coerced into only taking an alpha mate. When this social pressure is applied suddenly the population dynamics change to 15% alpha, 10% omega, and 75% beta. This social pressure doesn't increase the number of alphas but it does drive the number of omegas down. The problem arises because of pressures on the beta population. Any omegas that are produced between betas will be snapped up and removed from the general breeding population and beta/omega is not allowed also reducing the number of omegas in the general population. This is removing potential paths of spreading the O chromosome among betas. O would still be carried recessively by oB betas but this is where social convention again sticks its nose in and ruins things.

There's a general trend in fics for omegas to be described as 'submissive' and alphas as 'dominant' (many a fic was written about the feisty omega or the submissive alpha but they are exceptions to their cultural norm). Dominance is supposed to be the more desirable trait. Most fics set up a culture where it's expected that the mate doing the impregnating is dominant and the mate carrying the pregnancy is submissive. When this starts becoming applied to betas it screws things up further for alphas.

Let us assume that the recessive A and O carried by betas affects their behviour but not their genitals (I'll explain how in a later chapter). So an aB beta is slightly more dominant than other betas and an oB beta is slightly more submissive than other betas. There would be social pressure for aB betas to either mate with other aB betas because dominance is more desirable or to mate with oB betas to fulfill the dominant/submissive cultural expectation. An aB/oB pairing would be particularly valued because the pair would have a chance at producing an alpha child (which is more desirable). If this is a scenario where alphas do not take beta mates than aB/oB pairings would be the only way betas could attempt to have alpha children without breaking ingrained social taboos.

This social pressure to conform to the submissive/dominant dynamic and for alpha children to be favoured over all other sexes means aB betas and oB betas would strive to seek each other out over other beta combinations; aB/BB, oB/BB, and oB/oB are less desirable. An aB/oB beta couple would have a 1 in 4 chance of having an alpha child and a zero percent chance of producing an omega child.

Depending on the severity of the social pressure this strategy can quickly drive the numbers of betas up to 70% (or more if the fictional society in question is particularly aggressive about this) with most of those betas being BB betas meaning fewer people who carry the recessive A and O which lessens the chance for betas to produce alpha children (rivals) but it also lessens the chance of omega children (potential mates). So ironically if alphas want more omegas without producing more competing alphas it would be in their best interests to socially pressure for submissive/submissive pairings, whether that be omega/omega (100% omega offspring), oB beta/oB beta (25% omega offspring), or omega/oB beta (50% omega offspring). But alas, alphas tend to be short sighted and create the very problems they complain about.

But if alphas are all crazy about producing their own alpha children why don't they take alpha mates? Two alphas would have a 50% chance of more alphas and a 25% chance of making an omega which they all so desperately want (the last 25% being miscarried nonviable AA zygotes). This seems like a good idea as far as passing on alpha-ness to their children while still producing at least some omegas.

Fic convention seems to be of three opinions on the matter when it comes to why it doesn't work, a) it would be too much aggressive dominant bullshit for one couple to deal with, b) female alphas have a hard time conceiving and carrying a pregnancy, or c) alpha females are completely sterile. If a is true well, that is just a wacky cultural problem and they can either get over themselves and make it work between two alphas or else they'll just have to deal with potentially half their children being omegas. As far as c goes, well, personally I call bullshit on the sterile trope, if made up biology can create a functioning male omega then it can create a functioning female alpha. I am very pro chicks with dicks. But that is beside the point. The point is, the AA nonviable chromosome combination makes b the most likely reason alpha/alpha pairings are not as highly sought after (plus it would explain the 'female alpha has pregnancy difficulties' trope that's rather popular).

Nonviable AA means two alpha parents would be at an increased risk of miscarriage for every pregnancy (so too would an alpha/aB beta and aB beta/aB beta couples). Women, regular human women, experience miscarriages at a rate of somewhere between 8 to 20%. Assuming that most human things translate to a/b/o creatures an alpha female producing offspring with another carrier of the A chromosome would first experience a 1 in 4 chance that her pregnancy would be automatically terminated due to a nonviable AA chromosome combination and then experience a miscarriage rate of 8 to 20% on the remaining 3 in 4 pregnancies. Overall alpha/alpha pairings would experience a far greater number of miscarriages and that would probably be enough to consciously chose to not seek out alpha/alpha pairings. This would hold true for aB/aB beta and alpha/aB beta couples as well. Thus any couple where both parents have an A chromosome they would experience difficulty at successfully conceiving and producing live offspring. This would discourage the dominant/dominant pairings and encourage dominant/literally anything else pairings. But considering the value placed upon dominance and alpha children it's entirely possible this might be disregarded (and according to fic conventions it often is).

Also consider the tropes that plague omega children. They are often considered less than desirable offspring despite being desirable mates (catch 22, I guess). It may be that an alpha would be willing to take an alpha mate despite the downfalls because there would be a lesser chance of producing an omega child. Similarly an alpha may prefer an aB beta mate because there is a 0% chance to produce an omega child, though they give up the higher chances of producing alpha offspring (only 25% chance) and still have difficultly conceiving. This would explain why most fics do allow for alpha/beta pairings (though often as secondary or background pairings) but the preferred pairing remains alpha/omega because of the fewer lost pregnancies.

Over all this desire for alpha children (while omega children are undesirable) and dominance as a desirable trait implies that the most coveted pairings would be:

  • alpha/alpha (50% alpha offspring, 25% omega offspring, 25% nonviable)
  • alpha/omega (50% alpha offspring, 50% omega offspring)
  • alpha/aB beta (25% alpha offspring, 50% beta offspring, 25% nonviable)
  • aB beta/oB beta (25% alpha offspring, 75% beta offspring)
  • alpha/oB beta (25% alpha offspring, 25% omega offspring, 50% beta offspring)

Depending on how highly dominance is considered desirable and attractive aB beta/aB beta (0% alpha offspring but hella cool) might also be more socially acceptable than other beta/beta pairings.

This trend would shift the population to 30% alpha, 15%, omega, and 55% beta. So alphas, preferring alpha children and holding dominance as a standard and removing omegas from the breeding pool of betas actually increases the numbers of alphas being born- which is not a good thing if you consider mate competition.

So what is going on with BB betas under all this social pressure to produce alpha children and be dominant assholes? Well either they're trying to conform to the dominant/submissive cultural standard and win themselves a mate with an A or O chromosome thus playing the long game where their grandchildren could potentially be alphas or they just don't give a fuck and get along with their lives and pair up with other BB betas. Considering the drama that goes on in the alpha/omega portion of the community this may be a better survival strategy. 

Then there is the elusive omega/omega pairing. 100% omegas 100% of the time. Why aren't there more fics where the cultural norm is for omegas to mate with omegas just to bolster the numbers? It's very strange. Yes, there is social pressure for omegas to not seek out omega/omega pairings but when you look at the cultural standards in most fics, using omegas as baby making machines is par for the course. Normally they produce alpha children but it seems odd that they aren't very often used to make more omegas.

Some fics go the route of the omega males having a vestigial or barely functional male reproductive system. If that is the case then populations without social pressures would naturally hover around 70% beta, 20 % alpha, and 10% omega. Considering the amount of estrogen needed to conceive and then maintain a pregnancy this does actually have some merit. However in many fics omegas don't often know that they are omegas until later in life, sometimes as late as their mid to late 20s. This would be more than enough time for male omegas to develop normally and have fully functional equipment below the belt (or if they don't it should be a tip off that they're an omega). They could, over time, lose the ability to produce sperm. Younger male omegas looking more traditionally male and being fertile both ways while older male omegas are no longer capable of fathering children, a sort of male menopause (spermopause?), and probably have some form of erectile dysfunction and breast development. Of course we could just hand wave and say the high levels of estrogen don't affect male omegas physical appearance or ability to get it up. This is fiction after all.

While there is ample argument to be made that perhaps omega/omega does not result in offspring there is also a number of trends to suggest that it could. Enough fics have alpha/alpha pairings producing viable offspring that it seems odd that alpha females continue to have functioning ovaries but omega males lose their ability to produce viable sperm. Alternatively if alpha females are a completely sterile part of the population because the mix up with the plumbing just doesn't work then it would stand to reason that all omega males are also completely sterile which is obviously not the case. Another trend in fics, which I'm guessing is more likely due to lack of knowledge rather than actual authorial intent (and hey that's okay we all start somewhere), is that male omega's ejaculate is often described as white and to put it simply if the junk ain't working because of extreme hormonal changes that shouldn't be the case. I'll delve into this further in the biology section instead of rambling off topic here.

Ultimately whether or not omegas are capable of successfully producing offspring with other omegas has little bearing on the overall population dynamics when social pressures prevent them from doing so in the first place.

Another point to consider: the large number of fics that have couples who have all alpha offspring and occasionally that one dejected omega child that ruined everything. The majority of these fics are either alpha/omega or alpha/alpha. At first glance alpha/omega seems like it doesn't work for these stories since they produce 50% omegas and 50% alphas, except that is the rate across all births. One individual couple may have all alpha children. It's just as likely as that family that has all boys or all girls. Just because the first child was an alpha does not mean the second child will be an omega. The coin is flipped each time a child is conceived and the results of the last toss do not affect the results of the current toss. A run of two or three alphas is not unusual. On the other hand alpha/alpha pairings have a 50% chance of producing alpha children but only a 25% chance of producing omega children (the remaining 25% of pregnancies end in miscarriage due to the nonviable AA combination) and this would fit very well for stories about that above mentioned, one dejected omega child in a family of alphas. Since the protagonists' families are the only families we usually hear about in a fic it's entirely plausible that other families in a fic have more evenly distributed biological sex among their offspring and that the protagonists simply come from those oddball families that have the human equivalent of all girls or all boys.

Various Conclusions

So, what is the take away here? This model for trinary sex determination naturally favours the production of betas and the O chromosome is actually much more prevalent in a/b/o communities than what is readily apparent. Despite this, social pressure plays a large part in inhibiting the number of omegas by discouraging betas from beta/beta pairings that would result in omega children and by preventing beta/omega pairings, and potentially omega/omega pairings, which would also increase the total number of omegas.

The sterile alpha female trope has a variety of problems associated with it when omega males are apparently hyper fertile. I'm not sure if this is a lack of imagination on the author's part, where does a penis go on a female? (Don't worry I'll cover that), or if there's some other insidious factor at play. Are women not women if they have a functioning penis? This isn't true for the real world so why is it convention in so many fics? Especially considering omega males are still considered men despite having a vagina and giving birth. 

Also, alphas have poor long term management skills and need to get over this whole dominant thing.

Chapter Text

How did a three chromosome sex determination system evolve in higher vertebrates alongside a two sex determination system? First: let us disregard a slew of biological factors that would make human seeming simultaneous hermaphrodites biologically costly and insanely complicated, for this is fiction and we can do that sort of thing. Second: platypuses.

Platypuses are crazy. Not only are they weird egg laying electrolocation-using venomous freak mammals but they have 10 chromosomes that determine sex and they don't even all appear to be distinctly mammalian. They've got some weird Z/W type chromosomes going on too, potentially linking avian sex chromosome systems with mammals.

What the hell platypuses?

Also, thank you platypuses because you make a/b/o verses less wildly illogical. 

So if the noble platypus can teach us anything it's that you can totally get away with weird stuff in nature and if multiple fandoms building a shared AU which has defined rules about vaginas in butts isn't weird I don't know what is.

What does that mean for the three chromosome model of A/B/O? and how does it relate to XY? Well sex determination is less three chromosomes and more four. X/Y still determines if an individual will be male or female but a combination of A/B/O are responsible for actually building the parts and expressing that. This means any given individual will have four sex chromosomes.

Another Brief Note

In this scenario we actually have the potential for two sets of incompatible chromosomes: AA (from alpha/alpha, alpha/aB beta, or aB beta/aB) and YY (from two males). Now I've decided that AA always results in nonviable zygotes. It could be that YY is also nonviable or perhaps it functions perfectly fine. Humans with XYY syndrome don't have much in the way of symptoms of the chromosome abnormality, so perhaps in a/b/o worlds YY isn't a problem. In which case it's entirely possible that YY is found throughout the male population of any a/b/o world since male betas and male alphas can reproduce with male omegas. Another option is the male omega, through some twist of biology, only produces X carrying gametes, or potentially only produces X ovum but produces X or Y sperm. The choice is yours! Ultimately that issue has little bearing on this particular exercise in fake science so I'm disregarding YY. Let's move along.

Fake Science

Now as previously stated I'm biased towards the chromosome model where B is dominant to A and O, A is dominant to O, O is always recessive, and AA is nonviable. So this explanation of how and why is using that model but with a little jerry-rigging it can be applied to any three chromosome model in a/b/o creatures (Check out Appendix II for other three chromosome models).

So how does this work? My theory is that a/b/o creatures do not have two sex chromosomes but four. X/Y is still responsible for determining male or female but A/B/O is responsible for interpreting the X/Y and for actually building the reproductive organs.  So, the possible combinations of chromosomes for any individual to have are: XXOO, XYOO, XXAo, XYAo, XXoB, XYoB, XXaB, XYaB, XXBB, or XYBB. 

In most creatures that use X/Y sex chromosomes they use one of two sex determination systems. Method 1: a gene counting the number of Xs. Fruit flies for example use this method. Their sex determining gene looks at the number of Xs. If one X then it’s a male. If two Xs then it’s a female. Method 2: a gene that detects the presence of Y. Humans are an example. If the gene finds a Y it’s a male. If the gene doesn’t find a Y it’s a female. I put forth the idea that a version of both these genes are in play for a/b/o creatures and are found on the second set of sex chromosomes (A/B/O). Thus the X counting gene and the Y recognizing gene both play a part in determining biological sex in an a/b/o creature.

The next idea I put forth is that the A/B/O chromosomes are not waiting to turn on the production of one set of reproductive organs but are awaiting instruction as to which one to turn off. Thus A/O/B chromosomes are primed to build both sets of sex organs until told otherwise. To make this work this means two things:

  • The X counting gene isn’t counting one X or two Xs it is only looking for two Xs. If it finds two Xs it instructs the creation of a male reproductive system to turn off. If it does not find two Xs it doesn't care. It's not it's job to worry about one X.


  • The Y recognizing gene only cares about whether or not a Y is present. If a Y is present it instructs the female reproductive system to turn off. If a Y is not present it doesn't care. It's not it's job to worry about X.


Now here is where we once again assume: A and O are actually faulty mutations of B.

What does this mean for alphas and omegas? Well, they have faulty chromosomes. The A chromosome recognizes when to turn off the program for a female reproductive system but doesn't know how to turn off the male reproductive system. The O chromosome recognizes when to turn off the program for a male reproductive system but doesn't know how to turn off the female reproductive system. This results in male alphas that are phenotypical males and female omegas that are phenotypical females but it also results in female alphas with both female and male reproductive systems and male omegas with both female and male reproductive systems. Or more succinctly chicks with dicks and boys with butt vaginas (we're going to hand wave a little bit there and say the, quite frankly, huge biological requirements for female alphas and male omegas is somehow neatly taken care of through the power of *jazz hands* genetics). 

Because of the hierarchy I’ve set up for the A/B/O chromosomes this means that when a fully functional B is present it will always be the chromosome to determine sex. This is why betas don’t present as simultaneous hermaphrodites when they carry the A or O chromosome. This also means that all A/B/O chromosomes are carrying the information on how to build both male and female reproductive systems but that only one chromosome is active at a time (FYI, chromosome inactivation isn't some wacky thing I just made up. We'll cover chromosome inactivation in the section below).

If I've lost you and you're wondering what this looks like I drew some diagrams.

First, Betas, who have both the X counting gene and the Y recognizing gene.

geneticbetafemale geneticbetamale

As you can see everything works out handy-dandy for betas. The X counting gene and the Y recognizing gene are both present and both function correctly.

Now lets look at what happens in omegas who are missing the Y recognizing gene.

geneticomegafemale geneticomegamale

For female omegas everything works out fine. The X counting gene finds two Xs and turns the male reproductive system off. The lack of a Y recognizing gene does not affect them. For male omegas however things don't go as planned. The X counting gene doesn't find two Xs so it assumes its job is done, the Y recognizing gene should take over, but as can be seen omegas do not have the Y recognizing gene so the instructions to build a female reproductive system stays on. Both sets of reproductive organs are built.

Now lets look at what happens in alphas who are missing the X counting gene.

geneticalphamale geneticalphafemale

Male alphas are not affected by a lack of an X counting gene. Their Y recognizing gene functions correctly and turns off the female reproductive system. Female alphas however run into a problem. The Y recognizing gene is present and finds no Y. It keeps the instructions to build a female reproductive system on. At this point the X counting gene should kick in and tell the male reproductive system to turn off except alphas lack the X counting gene. There is no way for a female alpha to turn off the creation of the male reproductive system. Both sets of reproductive organs are built.

A Note about Chromosome Inactivation

In many X/Y sex determining species inactivation of one X chromosome in females is random but this is not always so. In marsupials the X chromosome that is inactivated is always the X chromosome from the father and this inactivation is not complete. Even in species where X inactivation is random a small portion of genes escapes this and stay active. This allows for two things important to my whole teetering mess of world building. First, it gives us precedent as to why A/B/O chromosome inactivation isn't random and second it allows for some traits from the A and O chromosomes to express in people who are carrying them as recessive chromosomes.

This means that in aB and oB betas deactivation of the A and O chromosomes is not random but directed. A and O will always inactivate when B is present. The same is true for alphas, who are all Ao, when it comes to the O chromosome. O will always inactivate when A is present. 

However since the inactivation is not 100% certain traits from the A or O chromosome will still express in individuals who carry them. This gives us those dominant betas and submissive betas I was talking about earlier and allows us to attribute the increased sex drive and rut cycle of alphas to the O chromosome (which I find delightfully ironic).


This nifty 4 sex chromosome with four of five possible chromosomes in play in any given person explains biological sex in a/b/o verses in a nice and neat manner and by making A and O abnormal chromosomes and the B chromosome being the original it explains why betas exist at all.

Chapter Text

Now it's time for a biology lesson— a made up biology lesson.


Everybody Smells: Scenting and Marking

So what's the deal with the scenting thing?

At least one of two things are going on here. Either the scents associated with biological sex are exceedingly obvious or a/b/o creatures have a very highly developed vomeronasal organ, accessory olfactory system, and accessory olfactory bulb.

If the scents associated with biological sex are so obvious that anyone walking down the street gets hit with them it would probably be a lot harder for all those magical scent blocking soaps and shampoos to work without causing their own problems. However most everyone agrees soaps and shampoos are mild or neutral smelling and usually work except for when plot devices happen. That means the more likely answer is the highly developed vomeronasal organ.

There's still a scientific community toss up as to whether adult humans have vomeronasal organs and process pheromone information or not but luckily a/b/o creatures are not human and thus we can say they have highly developed vomeronasal organs, accessory olfactory systems, and accessory olfactory bulbs and thumb it to science.

If you want a great big lecture on what vomeronasal organs, accessory olfactory systems, and accessory olfactory bulbs are I suggest Google. For everyone else all you need to know is that the vomeronasal organ is in the space between the nose and the mouth (this cold have some interesting implications on brain freeze in a/b/o worlds) and that the entire set up is great at detecting pheromones and is more directly linked with parts of the brain that deal with aggression, sexual responses, and mating behaviours.

Basically vomeronasal organs, accessory olfactory systems, and accessory olfactory bulbs work over time on detecting pheromones and alerting the brain that a possible fuck buddy or a rival is near by.

And because fics seem less inclined to have people sniffing each other's crotches, making weird flehmen faces, and sniffing at pee (well most fics) I think we should assume that a/b/o creatures are emitting larger quantities of pheromones than many other creatures and that omegas and alphas are producing even greater quantities than betas. It's also likely that the chemicals in slick trigger a greater response considering the tropes. But! These 'larger' quantities of pheromones aren't really enormous. The 'greater' quantities wouldn't be so great as to make soaps and shampoos ineffective, except possibly during a heat or a rut.

Interesting aside, development of the vomeronasal organ is apparently tied to testosterone to some degree so alphas would likely have better developed organs which makes that tracking down an omega in heat from two towns over trope a little more believable.

Now, on to marking.

Marking. Oh marking. What a hilarious one to cover. Alright. Let's immediately rule out using anal glands to mark (or if you'd like, maybe that's a mates only type of marking) because I've yet to see a fics where someone drops their pants in public and rubs their ass on someone or anyone describing a sticky funny smelling liquid coming out of someone's butt that isn't an obscene amount of semen or slick. Though the case could be made that omegas have some type of vaginal scent gland that gives slick its scent and that it effectively appears that male omegas are actively using an anal scent gland. 

In all likelihood a/b/o creatures probably aren't using most of the variety of other potential scent glands for similar reasons as the anal glands, fics don't described sticky liquids, oddly coloured liquids, or matted hair in association with marking. The most likely type of gland an a/b/o creature is using to mark is a sweat gland, specifically the apocrine sweat glands. You know all the parts on you that get super smelly and sweaty if you don't shower for a week? Those are the apocrine sweat glands. These sweat glands don't just sweat because of temperature, they're also tied to emotional responses. This works great for a/b/o creatures because marking is usually associated with emotions, specifically sexual responses.

a/b/o creatures probably have a few extra apocrine sweat glands because many fics have the protagonists marking with their wrists, faces, chest, or along the neck- this would make for some interesting body care products and deodorant commercials. However, not only would these points be good for marking someone, they are also the source of a person's scent. Deodorant would probably mess with a person's scent far more than a shampoo would. Those scent blocking soaps and shampoos really ought to be scent blocking soaps and deodorant.

Fun fact: hair removal would reduce an a/b/o creature's ability to broadcast their scent, so hairy armpits, genitals, and faces would probably be pretty normal in these worlds if there wasn't a general author bias towards less hair. People in these worlds who want to conceal their biological sex would be more likely to remove hair.


Mating Bonds and Bites

Almost uniformly across fics mating bonds are done by biting the neck, the crook of the neck, or the shoulder. Often times touching this spot is considered an erogenous zone so it does not appear to be inherently 'magic' but something biological in nature. Because of the consistency of the location and reaction to touch this makes it reasonable to believe there is some type of gland or nerve bundle there in charge of forming the mating bond. Thus we have my first made up science thing: the coniguim glandis (literally marriage gland).

The coniguim glandis would be a series of three glands and some associated nerves present in three locations: two on either side of the neck going down onto the shoulder and one on the back of the neck. The gland is activated by a particular enzyme- let us call it the bonding enzyme- in a person's mouth present at only certain times.

When are those certain times that the bonding enzyme is present? Fic convention generally agrees that mating bites are successfully given either during or right after an orgasm, or any time during a heat or rut. Essentially any sexually charged situation but not necessarily during sex.

Biting the neck imprints the coniguim glandis of the bitee on the biter by introducing the bonding enzyme directly to it. The bitee gains the 'benefits' of being bonded to the biter. Benefits being the usual possessiveness towards the biter, awareness of the biter, an emotional connection to the biter, etc etc, trope upon trope.

But why does the person bitten react at all to this? It seems bizarre that one bite can practically re-write someone's biology. Well, there's evidence to suggest it's not too wild of a concept. There's some scientific findings that suggest lone star ticks induce an allergy to a particular sugar making a person allergic to most meat products with one bite and toxoplasmosis infections in rodents make them less fearful of cats and other new things. It is a strange and creepy world where one bite/infection can alter a creature's basic biological reactions. Something similar must be happening to a/b/o creatures when a mating bite is applied.

In most fics just the scent of a bonded mate is enough to produce a reaction so this enzyme present in an a/b/o creatures mouth used to create a bond must be creating some form of positive association with the particular pheromone make up of the person who did the biting. It's less an allergy and more of a biologically induced craving or addiction, perhaps it messes with how dopamine, oxytocin, and vasopressin are produced. Catch the scent of your mate and get rewarded with a little blast of happy time chemicals.

This makes the near withdrawal bonded mates go into when separated in so many fics make quite a bit more sense. Their biology has been rewired to crave the person who bit them. It can even explain the more extreme version of this trope where if one of a bonded pair dies the other dies too, perhaps in these cases the 'withdrawal' type symptoms are so great the body can not physically handle it, kind of like going cold turkey after long term drug abuse. 

Now why is this enzyme active during heat/rut and after or during any orgasm and not just a response to penis in some orifice sex? Because that's goddamned ridiculous and I won't have it. Just no. The implication there is that there must be a penis involved and it must go inside someone. If that were the case than two female betas, two female omegas, just any collection of two or more people without penises, asexuals, and sex repulsed people, could not be 'married' in a/b/o worlds and like I said, just no. I do not want to be a part of that world.

Plus it makes the whole biting thing make even less sense if bonds are formed via a magical dick and there are enough fics to suggest that a mating bite can also be successfully given during a heat or rut without having sex.

Thus there are alternative methods for applying mating bonds for people who do not want to have sex and people without penises can still bond each other. Whether they choose to orgasm individually and then preform a mating bite or choose to bite each other during a heat or rut is up to them.

The enzyme being active during any orgasm or during a heat or rut also makes all the forced mating/rape tropes rampant through out a/b/o fics make more sense as well. Yes, sometimes rape victims do orgasm during rape but not all and many a/b/o fics that are rapey-er appear to go with: it doesn't matter if the victim orgasms or not they can still be bonded against their will. And I've come across enough fics where no rape occurred but the attacker was in rut but still forcibly bonded someone against their will. Which, unfortunately, reinforces the idea that mating bonds do no require penetrative sex nor are they always applied during sex.

Mating bonds are actually a little weird and creepy when you get down to it. Mind control? Withdrawal? Forced mating? It is a strange trope to be associated with love.

For those few fics that have people start the bonding process before they bite someone- and the fics where someone just knows that so and so is The One by scent alone- it's possible that scent glands nearby or on the specified mating bite areas could be broadcasting their own specific 'mating scent' that potential partners can pick up on and this creates a sort of pseudo mating bond. The feel good chemicals get released in a limited quantity but not to the full extant of the mating bond. Think of it as the gate way drug, if the scent is intoxicating then getting the real thing must be one hell of a trip.


True Mates

Is probably just a stronger version of the mating bond. For whatever reason the coniguim glandis and the bonding enzyme just function super well together. These people are probably experiencing some extreme changes to their brain chemistry and are a great candidate for that withdrawal from mate and dying trope. So basically mind controlled drug addicts. Happy soul mate AU everybody!


Slick: The Scent of Unicorn Farts

This is a short one.

Slick is likely a bodily fluid that prevents conception (the function of slick will be more thoroughly discussed in the next chapter). So why do alphas, betas, and omegas agree that it smells like rainbows and lollipops? This is either a result of association, slick is produced when an omega is aroused therefore the scent of slick means a greater chance of getting laid, or slick is carrying a pheromone that asserts an omega's receptibility to sex and may potentially be taken as a mate thus furthering their genetic line.

Slick having a desirable scent may be either a cultural fetish or a biological drive, it simply depends on how pheromone driven the particular a/b/o world is.


Nesting Behaviour

I'm including this in universal biology because it's unclear whether male betas are driven to nest or are simply acquiescing their partner's behaviour and female alphas tend to be described as nesters while male alphas are sometimes described as nesting. So potentially at least half of all betas and slightly more than half of all alphas exhibit nesting behaviours though it appears strongest in omegas.

Most pregnant mammals (except marsupials because they continue to be weird) will exhibit some kind of nesting behaviour before going into labour. a/b/o creatures tend to exhibit this behaviour to a large degree in the individual who is pregnant but may or may not exhibit it in the associated mate (which is often a plot trope in itself, an omega looking for that one alpha with a nesting instinct).

In the pregnant individual nesting is triggered by hormonal shifts related to pregnancy. The pregnant individual's mate is likely responding to their mate's behaviour but this is a/b/o so it's quite possible there's a 'nesting scent' that moves a pregnant individual's partner to actively desire to nest.

Unfortunately there isn't much more to say about it because few authors explore why a character is nesting beyond, the baby's due!


Estrous Cycle vs Menstrual Cycle

Omegas are really blindingly obviously going through estrous cycles. They aren't just going into heat they're going into some kind of heat overdrive half the time and fics very rarely, verging on never, describe omegas as having periods. I think I vaguely remember one fic that had omegas having a period. One. And I might have been dreaming that up. I think it is safe to say omegas have an estrous cycle and not a menstrual cycle.

But what about beta females and alpha females? They are a blank spot for the most part. Not very many fics deal with beta females or alpha females intimately but occasionally fic authors will toss in a throw away line about a beta female or alpha female needing pads or tampons or something to that effect and if they aren't producing slick why else would they be buying pads and tampons? However it's a rare enough occurrence that arguing for an estrous cycle or a menstrual cycle are both equally valid options.

Beta females and alpha females could be experiencing very subdued estrous cycles or they could be experiencing menstrual cycles. Just because omegas are very obviously experiencing estrous cycle does not inherently mean that beta females and alpha females are also experiencing them. It could be that a split in ovulation methods was produced through environmental pressures. When resources were plenty the best reproductive strategy would be to advertise fertility and produce as many offspring as possible. When resources were scarce it would make sense to down play times of fertility and have fewer offspring but focus more on the few born.

Having two different methods of fertility/ovulation in one species is not unheard of. Daphnia (water fleas), when the environment is favourable reproduce through parthenogenesis, it's fast and produces lots of offspring, but when the environment is not favorable sexual reproduction is used, it takes longer but produces more robust offspring. So if a real species is using both cloning and sexual reproduction a fake species using both an estrous and a menstrual cycle is not that far fetched. 

A note about estrous cycles: If you're hell bent on having omegas experience a 'period' during their cycle they are probably going to be doing it not only after but before a heat as well, first during the proestrus phases and again in the metestrus phase. So if you're giving them the gift of a period it's very likely they'd get two per cycle. Do you really want that? Nobody wants that. How many people who have periods want one? Personally I think we already put omegas through enough with the crazy slick production.


Presenting- the non sexy kind.

This is my all time biggest pet peeve in a/b/o worlds and I am sorry but I'm going to be incredibly biased on this one.

This really doesn't make sense. At all. Not unless everyone is born with both sets of reproductive organs and environmental factors are determining biological sex during late childhood but most fics seem to agree that biological sex is genetic and not determined by an outside factor.

If biological sex was determined by an outside factor where are all the fics where parents are choosing the biological sex of their children? -That could actually make for an interesting fic where there are only so many alphas/betas/omegas allowed to be made any given year, biological sex as government mandate.- I find it hard to believe that in these a/b/o worlds where biological sex is such a huge determining factor on personhood that absolutely no one has bothered to look into what environmental factor is changing children into alphas, betas, or omegas or alternatively that they know what does it but purposefully choose to ignore it in some very strange and elaborate social conspiracy and then punish or praise their children accordingly when they present. 

Presenting is everywhere in fics. And just, argh! mammals don't spontaneously produce organs overnight the way presenting always appears to be handled in fics.

The other problem with this is that female alphas should be painfully obvious at birth and a simple non-invasive ultrasound would easily identify omega males. There may be some confusion between omega females and beta females before puberty and alpha males and beta males before puberty but a simple blood test would probably sort this out. In AUs that are set before modern medical sciences or set in places without access to the medical facilities than the surprise omega male story makes slightly more sense, though considering how biased against omega males most a/b/o worlds are I'd think there'd be some cruder alternatives employed to suss out omega males from a young age.

Another problem is that so few people write alpha females as main characters (or as characters at all) that we really don't have a very good collective agreement on what is going on with female alphas in the first place. When alpha females are included and do have a penis we very rarely get fics that describe the entire presenting business and if they do discuss female alpha presenting it tends to be vague (if you've written an in-depth fic about female alpha presenting (you rare creature you) or know a fic send a link my way because I wanna read it!).

Or perhaps because female alphas are obvious at birth is why we don't have many female alpha presenting stories, but if that's the case than as I said before an ultrasound would be a simple test on an infant to determine whether they're a male omega. Which means there are a ton of worlds where parents upon seeing a dick at birth just immediately assume male children can't be anything other than beta or alpha and chose to not have an ultrasound done on their child. Which is absolutely bizarre. Most a/b/o worlds have huge biases against male omegas so you'd think parents would demand a test to see if their darling baby alpha is actually an omega. Then they can treat them terribly from a young age or ship them off to a breeding camp the next day, can't have them getting a false sense of personhood, now can we? (I'm sorry I'm bitter)

Honestly I think presenting is prevalent in so many fics because it's a great over the top metaphor for puberty and sudden changes and rejecting (or accepting) social roles; not quite fitting in with your family anymore or not living up to the expectations your family set or being an outcast from society.

But! My problem is this trope is almost exclusively applied to male alphas and male omegas. Where are all the female omegas/betas who want to be alphas? Where are the female omegas/betas who were raised from birth expecting to be alphas? Female alphas occasionally have this trope applied to them and when they do it's usually a bad thing, they shouldn't have been alphas. Except every single person in their world will talk about how great it is to be an alpha. Why are female alphas socially unacceptable when alphas are the be all and end all of a/b/o worlds?

So we've got five options for presenting:

  1. Presenting does not exist and let us never speak of it again.
  2. Not knowing biological sex and 'presenting' later in life is like the one thing in a/b/o fics that just cannot be unified with logic if biological sex is determined genetically.
  3. Parents are purposefully turning a blind eye towards their children's biological sex for some strange social conspiracy reason only to admonish their omega children (and sometimes female alpha children) later in life.
  4. Environmental factors are determining biological sex. This means all children have both sets of sexual reproductive organs but because it's completely normal in these worlds authors don't comment on it. In late childhood/early adulthood a mysterious environmental factor causes development of one set of reproductive organs over another to varying degrees.
  5. It's magic.


Presenting- the sexy kind

In case you're not sure what I'm talking about: people, usually omegas, sticking their asses up; porn ensues. 

Some fics seem to go with omegas (and other people) being instinctually driven to do it while others have them consciously doing it.

If they are consciously doing it then it's simply a funny little kink of a/b/o worlds.

If it's an instinct driven behaviour than it's actually called lordosis behaviour. Lordosis behaviour is a sex reflex. If omegas and occasionally betas (and very rarely alphas) are presenting because of lordosis this means they can't actually stop themselves from doing it. It's not something consciously done but rather done by instinct to facilitate mating.

This isn't actually something that needs all that much explaining. I just thought you might like to know the difference.

Chapter Text

Omegas tend to be associated with the following tropes: 'submissiveness' (despite most fics being about that one omega who is not submissive), avoidance of unknown alphas, heats, promiscuity (an omega is often described as craving anything even remotely knot shaped while in heat), and a metric ton of slick.

At first glance those tropes don't seem like they would have much basis in nature and that it's all just for porn but! These are all adaptations associated with avoiding injury during mating, ensuring mating during ovulation, and reducing infanticide through paternity dilution (ambiguous parentage). Minus some social issues, omegas are surprisingly well built for a world of aggressive breeding partners.

Let's dive into these tropes.


Avoidance and Submission

Omegas are often described as participating in avoidance strategies in fics: don't go out at night, don't go out alone, don't go out. Omegas wouldn't be avoiding alphas if they were cuddly teddy bears. Alphas are basically the epitome of aggressive sexual violence in tropes. Oh yes, the protagonist is almost always the most loveable alpha that was ever to alpha and perhaps some associated friends and family are nice but the fact that the slang term 'knothead' and the wandering alpha rape gang apparently roving every street is pervasive in so many fics leaves quite a lot to be desired from alphas. I'd wager a guess that in fics alphas are probably the number one cause of death for omegas.

So omegas are kind of boned (no pun intended) because alphas are dangerous and they prefer omegas as mates. That's dangerous for omegas. It's in an omega's best interests to either avoid them or figure out how to come away from alpha encounters alive. So why are avoidance and submission actually biological strategies for omegas? They Don't Die.

Avoidance is the most straightforward. If an omega doesn't encounter an alpha there is less of a chance an omega will be in a sexually coercive scenario that might lead to injury or death for the omega. This is a rather common strategy when potential mates are violently sexually coercive. You see it everywhere from dolphins to bedbugs. The more likely a female (or in our case omega) encounters aggression on the part of their potential mate the more likely they are to avoid it. But it's a catch twenty two. They have a biological imperative to seek out a mate and further their genetic line. So avoidance is only a good strategy for as long as they aren't trying to conceive. Which leads us to submission.

Submission is probably part biology part social conditioning. On one hand alphas are often described as bigger and stronger than omegas. If an omega decides to fight back against alpha sexual aggression this may very well end in the omega's injury or death. Submitting to sexual coercion would decrease an omega's chance of injury and death. Female baboons use a similar strategy for the very same reason, it keeps them alive with the least injuries.

Submission could also be used by omegas as a method of attracting and keeping a more desirable mate. A potential mate is more likely to prefer an omega that isn't trying to cause them bodily harm but considering the tropes this seems less likely.


Slick: Not Just For Porn

Slick is probably a very good antimicrobial because there's a whole bunch of unprotected rimming of omega males going on but no one is ever getting e.coli or protozoan infections. It's probably acidic in nature in order to gain that antimicrobial property. Not burn your dick off acidic but likely more acidic than what you'd find in a human woman's vaginal tract. This would help reduce infections in omegas' reproductive and urinary tracts. Considering the massive quantities of foreign cells introduced during sex with an alpha the sheer quantity of slick would also be a great way for omegas to keep clean by flushing out the copious amount of semen. Slick is a health benefit. 

Beyond the antimicrobial benefits acidic slick would have it would also act as a life guard in the gene pool. Can't swim? The pool too rough? Then get out. Slick is less likely to have originated as something to facilitate sex and more likely to be a method of discharging or defeating sperm, thus inhibiting conception. Ejecting semen and creating an inhospitable environment for sperm are rather common tactics of controlling paternity (chickens sometimes rather dramatically eject unwanted sperm). It would also fit in nicely with the many paternity dilution strategies omegas appear to employ and explain why omegas are creating such a large quantity of a liquid that is probably dehydrating their bodies. Slick means that only the healthiest sperm survives to fertilize an ovum and it helps to combat unwanted pregnancy if their avoidance tactics didn't work out as planned.

So while slick may have originated as a method of combating aggressive alphas and their sperm it is not intrinsically tied to heats because it's beneficial for an omega to produce slick during any instance of mating to help prevent reproductive/urinary tract infections. This is why slick is linked with sexual arousal rather than the estrous cycle. However more slick would be produced during estrus because omegas are more frequently aroused and are preparing to deal with a rather ridiculous amount of semen.


Heat: Fevers, Dehydration, and An Undying Love For Cock

Heats, or estrus, are a function of the estrous cycle and thus are the only time an omega can conceive. Generally speaking omegas appear to be polyestrous, meaning they aren't seasonal breeders but are continuously going through estrous cycles throughout the year. There are some instances of omegas having a mate induced estrus but even these omegas are usually polyestrous. Mate induced estrus may be a function of nature to make sure that a bonded omega and alpha are at peak fertility during the same time, syncing up the biological clocks so to speak.

At their most basic level heats are a fertility advertising strategy. They are giant biological neon signs screaming DO ME NOW!!! The usual symptoms in fics are: extreme desire for sex, promiscuity, slick production, and increased body temperature. Now, as stated above slick production is not actually a symptom of heat but a secondary response to sexual desire. So we won't be talking about slick production here but rather we'll be disusing how it lends to dehydration.

An extreme desire for sex and promiscuity don't necessarily go hand in hand but enough fics describe omegas willing to roll over for anything even vaguely knot shaped as many times as they physically can that it appears in this case they do. This is actually a great paternity dilution strategy to combat infanticide. As mentioned before alphas tend to be rather aggressive especially towards each other, among animals that can lead to infanticide by males. A male doesn't want a female investing in some other male's offspring, or in our case an alpha doesn't want an omega investing in another alpha's offspring. Very active promiscuity helps to prevent infanticide by making paternity unknown.

It's likely that somewhere in a/b/o evolutionary history omegas had legitimate fears that if an unknown alpha appeared their offspring might be killed. The easiest way to combat that without violence is to screw every alpha (and/or beta/omega male) available. An alpha would be less inclined to infanticide if they aren't sure the offspring is theirs or someone else's. Mouse lemur females employ this tactic and successfully shifts the violence of competition away from them and their offspring to competition between males via sperm production.

So biologically omegas are predisposed towards promiscuity but socially it's frowned upon. Which makes sense given how alphas want to know that their omega isn't going out to screw everyone in sight. It's in an alpha's best interests that they prevent that behaviour and most fics are set in worlds that are more concerned with an alpha's best interests. However think of the porn you could write if you set your fic in a world that catered to an omega's instincts.

Now about those heat fevers. Heats are uniformly described as being hot. Most fics play this up describing omegas as 'burning up', sometimes to an utterly life threatening degree. What purpose would this serve? Heats are supposed to be all about fertility and conception, right? Why the potentially life threatening increase of body temperature?

Likely one of two things are happening here, this is either an out of control evolutionary attempt to destroy unwanted sperm via temperature increase or it is an unintentional side effect of advertising ovulation. Both could be a reasonable explanation- evolution doesn't always make sensible decisions (look me in the eye and tell me insomnia due to hormonal shifts is a good evolutionary achievement)- and whichever is correct the outcome is still the same: it's potentially dangerous to omegas and it's likely detrimental to sperm.

If it is simply an unintentional side effect it is unfortunate and a potentially life threatening nuisance and I feel for omegas. If it is an actual response to unwanted mating well, I still feel for omegas. Either way it still boils down (pun intended) to inhibiting sperm and potential dehydration or heat stroke.

Heat stroke and dehydration are probably very real concerns for omegas during a heat. Their body has an elevated core temperature, they're participating in vigorous activities, and their body is producing an insane amount of slick thus further draining them of fluids, so authors make sure your omegas are drinking lots of water during heats or they'll be in need of a hospital.

Now, that all said, it's actually potentially possible that many heat symptoms are caused by or aggravated by alpha semen. Alphas are often described as smelling quite strongly and often smelling terrible to anyone that is not their mate. This smell might actually be a result of increased semen production and elevated levels of cadaverine, putrescine, and/or spermine (all of which I'll discuss in the next chapter). If alphas are potentially producing very high quantities of cadaverine, putrescine, and/or spermine they may be mildly poisoning omegas. Acute toxicity of these three chemicals can result in low blood pressure, paralysis, and an aversion to eating (among other things but these are the relevant symptoms for the purposes of our fake science). An omega in heat would be getting a much higher dose of these chemicals than an omega not in heat and would therefore be more likely to exhibit some of these symptoms.

Paralysis and loss of appetite seem rather in line with how omegas act after a bout of marathon sex or masturbation during a heat. They are often described as incapable of moving and generally portrayed as having forgotten to eat but these two symptom could actually be the result to exposure to cadaverine, putrescine, and spermine and not physical exhaustion and distraction. Omegas without an alpha partner during heat are described with these symptoms but an omega with an alpha partner tend to exhibit more extreme versions of them. Exposure to alpha semen might be making these symptoms worse.

The really interesting symptom of cadaverine, putrescine, and spermine exposure is low blood pressure (well, interesting as far as our fake a/b/o science goes). If I said, this omega is dizzy, completely out of it, passing out, can't see right they are so fucked out, and are thirsty as hell would you think heat symptoms or sudden drop in blood pressure? Dizziness, fainting, lack of concentration, blurred vision, and thirst are all symptoms of low blood pressure. But! The most interesting symptom of low blood pressure is that it also makes you feel cold. This is a very common trope in a/b/o worlds: an omega that spends their heat alone will 'burn up', an omega that spends their heat with an alpha will feel like they're cooling down. This could actually be a result of cadaverine, putrescine, and spermine exposure causing low blood pressure.

So heats over all are rather life threatening and alphas may be using some tricky biological tactics to get omegas to believe that having sex with them will help protect against the symptoms while it is in fact more likely they're making it worse; the omegas are all just passed out or disoriented and can't see otherwise.


Are Male Omegas Shooting Blanks Or Are They Highly Adapted Sneaks?

There is a slew of conflicting evidence. Some fics flat out state that male omegas have barely functional very small male vestigial genitals while many don't comment on the specific size and function except for in relation to an alpha's penis (smaller than an alpha penis seems to be the equivalent of saying my head is smaller than a house). Most all fics describe male omega semen as white with a bare handful describing it as a very small quantity of a clear fluid. Any fic that has presenting portrays male omegas as developing completely the same as male alphas or male betas up until the point of presentation (which is often much later in life). These things all together don't make sense and it appears that authors generally don't agree on this point.

If male omegas don't have functional sperm it's likely a result of the very large quantities of estrogen needed to maintain a female reproductive tract. If that is the case then male omegas shouldn't be surprised upon presenting (I still hate presenting) because they would start to notice their genitals aren't developing like male alphas and male betas early on. I'm sure male locker rooms would be a special nightmare for male omegas before presenting. Even without presenting male omegas should develop many more female traits if their male reproductive system is nonfunctional. The most obvious development: breasts. But rarely do they develop any feminized traits except for being described as 'slender' and maybe soft skinned.

FYI: There is a subset of fics where male omegas do develop breasts. These male omegas are the most likely to not be producing sperm and probably have much smaller genitals than other versions of male omegas.

Another option for infertility in male omegas is that alpha semen contains relatively high amounts of cadaverine, putrescine, and/or spermine. These three chemicals can negatively effect spermatogenesis. Male omegas may be receiving large enough doses over a long period of time that it destroys their ability to create sperm. However this would imply that male omegas that don't engage in sex with alphas are in fact completely fertile.

Fics that describe male omegas as looking exactly and completely 100% indistinguishable from male betas or male alphas until slick starts pouring out of their butts are probably worlds where a male omega has a functioning male reproductive system because it's the testosterone produced in the testicles that maintains male fertility and the outward male appearance.

Another point in favour of male omegas being fertile the 'male way': very rarely are they ever described as having erectile dysfunction. If a male omega is producing enough estrogen to effectively sterilize them erections should be harder to achieve and maintain. I've yet to read the fic where the male omega just can't get it up or has a difficult time achieving an erections and keeping it. Sure there may be some variation among male omegas but erectile dysfunction should be common enough among male omegas that someone should have commented within the fic on the male omega's ability to get an erection at the drop of a hat. But since no one ever compliments a male omega's ability to get a hard on I think it's safe to say this isn't an issue. Which means they're probably producing enough testosterone to maintain fertility.

And don't forget, male omegas are almost always described as ejaculating white semen which again means they're probably producing enough testosterone to maintain fertility since the various glands that produce semen need a reasonable amount of testosterone to produce those fluids. If male omegas weren't producing enough testosterone to develop the testicles, prostate gland (and boy do fics love their prostate gland), etc then they'd be ejaculating a clear fluid with little to no sperm (probably no sperm). Extremely few fics comment on male omega semiannual fluid as being anything other than average looking which would imply most male omegas probably have a reasonable sperm count.

We should also look at female alphas in relation to male omegas. If a fic didn't go the route of sterile female alphas then female alphas almost always make use of their female reproductive system. If a female alpha can use her uterus it stands to reason that it would be equally believable that a male omega can use his penis. It's simply social pressures (ours and in the fic) that prevent male omegas from fathering children.

From an evolutionary perspective it would be very beneficial for male omegas to be producing quality sperm because they would make the perfect sneaks.

What are sneaks? Well take a look at cuttlefish. Not every male is big and strong and aggressive. Some males are small and sneaky. The small sneaky males gain access to mates by pretending to be females looking for some lovin'. The sneak male, while impersonating a female, is invited into a mating situation by a big strong guarding male and while the guarding male isn't looking the sneak male quietly mates with the real female and leaves. The guarding male is then left to guard the sneak male's mate. 

Male omegas would bring their A game to this mating strategy. They're generally described as smelling like omegas rather than smelling like males. They don't smell like a threat, they smell like a potential mate. I can think of no better way to infiltrate an alpha's territory than by smelling like an omega in heat.

Imagine a male omega from early on in their evolution, they can't compete with alphas on a physical level to impregnate mates and defend a territory but they could easily submit to an alpha, live in the alpha's territory thus gaining all the benefits of protection from other alphas, and all the while they could be impregnating the alpha's other mates or nearby neighbours.

If male omegas have functional sperm then sneaking behaviour would probably have been rampant among early male omegas enforcing the promiscuous omega trope.

Viable sperm would also explain why omega/omega relationships are viewed as extremely taboo. A male omega mating with another omega would probably be viewed by alphas as betraying an unspoken agreement of mating and/or poaching potential mates for alphas. No other relationship seems to be met with the same level of vehement arguments against and I think this might be because of the 'false advertising' male omegas are doing. Their scent says MATE but in reality they are a potential competitor. Nobody likes a liar, right?

Male omegas producing viable sperm and 'stealing' potential alpha mates also does a lot to explain why there is a fairly good number of fics where the cultural norm is forcing male omegas into cock cages and other chastity devices. If there is an evolutionary history of male omegas sneaking into alpha harems and knocking up the alpha's mates it would be in an alpha's best interests to prevent that. 

Personally I am all in favour of male omegas being fertile both ways and being sneaky shits about it. Please give me all the fics of female alphas and male omegas knocking each other up and male omegas sneaking into alpha harems and having sex with everyone.


MPREG: How Do They Get It Out?

That's what you're asking yourself isn't it? How? How do they squeeze a kid out of their butt? Well omega males do have a female reproductive tract and presumably go through contractions during labour so it doesn't seem far off to just assume their equivalent of the anal sphincter is going through a similar dilation process as the cervix.

Here's some stuff you probably didn't want to know and you might want to skip if birth related things make you squeamish: in human women maximum dilation of the cervix and birth canal while giving birth is usually about 10 cm, four inch wide butt plugs are a thing and regular human people stick them up their butts. For the people that are not in the weird conflux that is Canadian mixed measurement that is basically the same size.

So yeah. Butts are already having baby sized things shoved into them and presumably taken out again. The actual physical constraints of shoving a kid out of a body probably aren't all that different for omega males as they are for females. However it would probably be in an omega male's best interest to do some perineal massage and 'train' before giving birth. Perineal massage is really just a fancy way of saying birth canal widening. It's either done with fingers or with some aids and it's goal is to stretch the birth canal to that 10 cm goal before labour.

Another thing you probably didn't want to know: vaginal tears during labour are pretty common, so I guess the omega male equivalent would be anal tears. If that perineal massage didn't work then episiotomies are usually the next step. This is a procedure where perineum is purposefully cut to make it easier to squeeze a kid out of your vagina. That doesn't sound like fun for anyone.

Basically: labour is hard on anyone and there are fewer size constraints than what you'd think.


Cloacae: You can have them if you want

What is a cloaca? Alright, here is the short version for females only: in birds, reptiles, amphibians, and some mammals the intestine, urethra, and vagina open into a common chamber called the cloaca. Everything that's on the inside that wants to be on the outside has to pass through the cloaca and all sex starts with a cloaca. A cloaca is located at the terminal end of both the intestine, urethra, and vagina.

And it is probably the worst idea ever for male omegas. The problem is male omegas are still considered omegas. Female omegas don't have a cloaca. Male omegas don't really have a cloaca either because as far as I can tell they're still peeing with their dicks. But for the sake of this section we'll call the rectal/vaginal combo a cloaca. Anyway, female omegas don't have a cloaca and this is a bit of a problem for male omegas. It means male omegas probably aren't specially adapted to dealing with cloacal sex and a knot actually might make this worse.

See, the problem is most people equate cloacae with birds and this is an issue when alpha dicks are generally equated with canines. Either it shouldn't work or most male omegas should be suffering from massive uterine infections.

If an alpha is sticking their dick all the way in and knotting an omega but the vagina stays closed they are leaving their sperm way the hell up in the rectum and potentially keeping the vagina closed with their knot. Here, I drew a shitty diagram for you:


(I just realized I didn't draw legs on this diagram)

As you can see an alpha might very well be inhibiting their own chances of conception because of their knot.

I will not draw the other option wherein the penis manages to enter the vagina after passing through the cloaca because that involves ramming fecal matter up a vagina and I'm just not that far gone that I feel the need to draw that. But suffice to say even with the idea that slick is antimicrobial shoving a dick through fecal matter and then into a vagina is not a good thing. We can probably guess that male omegas do not have short cloacae because they're getting pregnant as soon as an alpha so much as looks at them and they aren't dying in droves from uterine infections.

(While, yes, there is not always fecal matter in the anus/cloaca there would be sometimes and I have never read an a/b/o fic where a male omega has said, "Oh, hey, I really need to go to the bathroom before you shove a dick up my butt." Omegas are always 100% available at all times. Also, even if there is no fecal matter currently in the cloaca this would still be the equivalent of having anal sex then vaginal sex which is not something you should be doing if you don't want to risk infections)

It's more likely that if male omegas have a cloaca that it's much longer; one that accommodates the size of an alpha. It would look something like this:


(No legs again and apparently a flat ass)

This works out far better than the shorter cloaca and now the copious amount of semen an alpha produces makes a bit more sense; they have to produce more because their penis isn't even reaching the vagina. But this also means the the cloaca is upwards of five inches or more long (probably more) and as I said before this presents a problem because male omegas seem to be more closely associated with birds. If the cloaca is very deep and the vaginal opening is way the hell up inside an omega this poses some problems for birth since in birds the cloaca and vagina practically turn inside out (no really go google how eggs come out of chickens) in order to close off the intestine and leave offspring relatively clean instead of covered in whatever was in the cloaca before birth. I'm not sure how well that would go over in something human sized.

Cloacae make male omega birth complicated and possibly even more dangerous than a regular birth but fics rarely comment on male omegas having strange birthing practices. They appear to be more or less having babies the same way female omegas are having babies. There's definitely no mention of protruding cloacae or inside out vaginas.

In short, male omegas are not birds, rather they are functional mammalian hermaphrodites from a species that does not have cloacae in any other biological sex. There's no reason for their vagina to open into a cloaca or be way the hell inside them like some secret sex nesting doll. Like a female alpha they've got some developmental abnormalities but those abnormalities do not necessarily mean a cloaca.

And to leave this on a gross point that argues against cloacae, I've yet to read a fic where there were some 'surprises' in the slick as it cleans out the cloaca before sex. 


The Case for the Epivagina in Male Omegas

Here is my new made up thing that I would like to persuade you to use: the epivagina, literally over/upon the vagina. This is based upon a few things in fics, a) authors are generally incredibly vague about how male omegas give birth, b) many male omegas need little to no prep before they're impaling themselves on a cock, c) no one ever complains about literal shit after sex with a male omega, and d) no one is getting bacterial infections from eating out a male omega.

So what is the epivagina? The idea is simple. The rectum and the vagina don't share anything except a common dividing 'wall' which is the epivagina. The rectum and the vagina only appear to share an external vent and perhaps the external sphincter does loop all the way around but it is divided through the middle by the epivagina. When a male omega is not aroused the epivagina is in a relaxed state that leaves the rectum open and covers the vaginal opening. When a male omega is aroused the epivagina expands, much the way a human woman's vagina expands during arousal, and pushes backwards opening the vagina and sealing off the rectum.

What does that look like? Well you're in luck, I've got some more shitty diagrams for you.

unaroused aroused

(I forgot to label the anus on both of these. Whoops)

This explains why male omegas can practically leap onto cocks and why alphas aren't complaining about getting dosed with e.coli after oral sex; they aren't having anal sex, they're having vaginal sex. This plays on that earlier idea back in chapter 3 that male omegas have faulty genes that want to build both male and female reproductive organs but instead of the female reproductive organs ending internally and leading to a cloaca they end externally; just very close to the rectum in order to make room for all those extra reproductive organs. Essentially the perineum (that space between vagina and anus) is very very small.

But what about all the prostate kinks you ask? Never fear. Absolutely nothing has to change about how you write porn. The prostate can still be accessed in a similar manner through the interior of the vagina. Here is my diagram to prove it:

male omega diagram

(yes, I gave male omegas an internally located clitoris)

Another reason I would like you to consider this is that: male omegas nearly universally seem to get off through penetration alone. Prostate orgasms are not the most reliable of orgasms. Many people with prostates will generally agree it takes a bit of work to orgasm this way. And people with vaginas will generally agree it takes more effort to orgasm from penetration alone without any clitoral stimulation. Do you see where I'm going here? If there's an internally located clitoris in male omegas it would explain why they orgasm more easily from penetration alone and why they prefer partners with knots; penetration immediately stimulates the clitoris.

Now, I might have lied a little about nothing changing about how you write porn if you swap out a cloaca for an epivagina. Your male omega can now have a clitoris easily accessible by a tongue. You can write fics where someone can slide their slick covered fingers inside a male omegas slick soaked hole to rub maddening circles over their prostate while using their tongue to do the same to their clitoris. You've got three orgasm options now. Plus, you can come up with some kinky double pronged vibrators especially made for omegas or weird curvy vibrators made to hit all the sweet spots. You can still have all the various plug wearing kinks because the epivagina in conjunction with the external sphincter would hold it in place.

Overall epivaginas are a win/win scenario for porn purveyors and male omegas alike. We get more options for kinkier sex and male omegas aren't getting fecal matter shoved up their reproductive I'm sure they'd enjoy the kinkier sex.

So, epivagina, feel free to flagrantly steal this idea.


A Minor Addition

Some a/b/o fics circumvent the entire is it anal or vaginal sex? debate by just straight up giving male omegas a functioning vagina completely separate from the rectum. In that case the vaginal opening is usually located directly behind the testicles and functions like a completely normal vagina. There isn't really much to explain about it, it's a vagina. The internal reproductive tract would probably look like the above diagram but with the vaginal opening being completely separate from the anus.


A Quick Aside

Male omegas are probably at less risk for heart disease than other males because their bodies would be making more estrogen which protects against it. Also, they'd probably be less likely to go bald for similar reasons. So there's definitely some upsides to being a male omega.


Chapter Text

What are the tropes for alphas? Aggression, chase responses, ruts, knots, and possessiveness. These are all mostly used to paint alphas as power-hungry knothead stalkers. Of course, some alphas rise above this but they are often the exception in many fics. However there might actually be a few biological imperatives in play for this behaviour and not just terrible social upbringings.

It's likely alphas came by their reputation honestly somewhere in their early evolutionary history rather than suddenly developing these behaviours out of the blue. These tropes all suggest a fairly high level of mate competition which an alpha would need to combat in order to pass along their genetic information. They likely needed to fight rivals, both physically and through sperm competition, and combat an omega's tendency towards promiscuity. Most alpha tropes would actually help them to further their genetic line.

What's also interesting is that this means during the evolution of a/b/o creatures alphas began preferring omega mates over beta mates since most of the tropes that are applied to alphas are direct responses to omegas. This means that omegas drove the sexual dimorphism of alphas just as much as alphas must have driven the sexual dimorphism of omegas.



This is actually a really interesting trope because it's one of the few tropes for alphas that doesn't associate them with predators. Ruts are found in the real world in herbivorous prey species; think deer and antelope. So when alphas are at their most basic and arguably at they're most vulnerable (mentally not physically) they're acting out the behaviour of prey animals. That is not to say that a moose in rut isn't dangerous simply because it's a herbivore but it is an interesting choice in words in fandom writing. 

So what is a rut? Well it's exactly what fics say it is, a drive to mate along with a double shot of testosterone. It makes males (in our case alphas) more aggressive and less cautious and actively seek out or attract mates. It's also the time period when alphas would be making the most sperm, or in technical terms 'the best quality semen' because who doesn't want that? A rut is when an alpha would be most likely to impregnate their partner (potentially it could be the only time they can impregnate their partner).

Alpha ruts do not appear to be linked to a particular breeding season but rather, like omegas and heats, experience ruts throughout the year. This is likely a result of omegas being polyestrous. It would be in an alpha's best biological interests to be in rut whenever an omega is in heat instead of just once or twice a year. It appears that ruts can also be induced in alphas if there is an omega in heat nearby but it's questionable whether it's an actual rut or learned behaviour because not all alphas go into rut when near an omega in heat. But, some alphas do appear to go into a full blown rut so perhaps these alphas are simply more sensitive to pheromonal shifts in omegas.

(Sadly no one seems to go all the way with rut behaviour but I think wallowing alphas would be funny. Seriously, where are the fics where alphas wallow? Because I would read 2000 words of an alpha in rut mindlessly enjoying rolling around in mud and then realize that they're going to miss their high powered lawyer conference and then showing up covered head to toe in mud. Also, self-anointing (for my own preferences not with urine but I'm sure it floats some people's boats) could also be entertaining. Alphas mashing bugs and smearing it over themselves, alphas rolling in weird smelling stuff, alphas rubbing leaves all over their skin. Then those same alphas trying to persuade omegas that they actually smell and/or look great after they've been rolling in something they found dead on the beach. I may have an odd sense of humour but that has me in stitches).

When alphas in rut are portrayed as particularly violent their behaviour becomes less rut like and more like a male elephant's musth. Musth is a similar concept to rut except that mating is not the primary drive of musth, instead it (at least topically) appears to be violence. An elephant in musth will have a testosterone spike that can exceed sixty times their average amount of testosterone, literal testosterone poisoning. They become physically dangerous to everyone and anything around them, even potential mating partners. This sounds much more in line with the mindlessly violent alpha in rut trope. So potentially alphas in some worlds are not experiencing a mild increase in testosterone but instead a rather huge overdose.

This extreme violence that could easily lead to their own demise seems counter intuitive for alphas looking to have the maximum amount of offspring but this could be the result of evolving in an environment where resources were very scarce and mate competition was very high. Killing everything that might pose a threat to future offspring no matter the physical cost to their own bodies would give their offspring the best possible advantage. This would also guarantee that they would be the alpha doing all the impregnating. The tiny marsupial antechinus uses a similar method of breeding; males literally disintegrate as they do absolutely nothing but guard and mate for a month or two before every breeding male dies.

The mild version of rut trades knowledge of paternity for physical health while the extreme version of rut trades physical health for knowledge of paternity.

Both styles of rut could have their potential benefits. In the mild version of rut much of their focus is on finding a mate and keeping that mate to themselves. This behaviour would help to ensure that their mate's offspring is their own with only slight risk of bodily harm to themselves. The far more aggressive version of rut could be a strategy aimed at removing competition. Essentially, the best way to ensure that it's their genes passed on is to make sure everyone else is dead. This version of rut removes competition directly but it can also put themselves and any potential mates at risk. So think of mild ruts as planning for the future and extreme ruts as gambling on the present.

Also, all this testosterone during ruts probably puts alphas at higher risk for heart disease.



The technical term is bulbus glandis. I'm going to assume that if you've gotten this far you know how the whole knotting thing goes down during sex.

So what are knots? They're a part of the erectile tissue at the base of the penis and have a ring of muscle around them to facilitate ejaculation once they've swollen and locked inside a mate. That muscle will contract on and off for the duration of the time that the penis is locked inside their mate. Some fics say this time span is maybe ten minutes long, other fics make it an hour or longer. There doesn't seem to be any consistency with how long a knot is actually swollen and locked in place. However you might want to consider that after 4 hours an erection is officially a medical problem and can lead to everything from erectile dysfunction to gangrene.

Also, knots probably look like weird lumpy-bumpy flesh disks. I made that really attractive didn't I? Well, in all honesty they probably aren't super attractive. You can google bulbus glandis and see what I mean or you can google bad dragon and look at stylized dildos based on dog penises that are slightly more aesthetically pleasing to look at. The choice is yours.

Now why would alphas develop a knot? Well, it's likely biological sexual conflict that's led to this high degree of sexual dimorphism. Knots are a method of combating promiscuity in omegas. If an omega can't leave for upwards of an hour or two the chances of conception are higher. Think of a knot as a temporary mating plug but instead of some gelatinous goop to keep an alpha's semen in and other alphas' semen out alphas take a more hands on approach. A knot effectively keeps an omega in one place which may allow for future instances of mating, plus it assures the alpha that there were no sneaks in the bedroom.

A knot gives an alpha as much of a chance of assured paternity as it can possibly get.


So Much Semen You Could Drown A Small Animal

Sorry, I really like that title.

Alright, I haven't yet heard of the alpha that needed a ball bra so I think it's safe to say all this extra fluid that could fill a small bathtub isn't coming from the testicles.

While an alpha's testicles are generally described as larger they probably aren't absurdly so. The larger than average human male testicles are likely a result of omegas being promiscuous (which, if you remember, was probably in turn driven by infanticide). This is common across most mammals, males with larger testicles have promiscuous mates. In apes, for instance, chimpanzees have huge testicles and produce tons of semen because females are very promiscuous while gorillas on the other hand have rather small testicles and live in small polygynous bands with little to no promiscuity. Humans are about middle of the road in the testicle size department. Alphas are probably closer to chimpanzees. But even at that size, alpha testicles can't conceivably be holding the copious amount of fluids that appears in fics.

The more likely places that all this semen is coming from are the seminal vesicle and the prostate. These two glands are responsible for most of the fluid in semen in humans so it stands to reason they're the source of most of the fluid coming from alphas. However with alphas they must be significantly enlarged. How much larger they are from regular humans would depend upon how much semen they're producing. If your alphas are producing just a bit more semen than an average human male they probably aren't that large. If your alphas are producing litres of semen the seminal vesicle and prostate would be much larger.

All this semen is likely a direct response to slick in omegas. If slick is creating an inhibiting environment for sperm then an alpha would need to introduce something into that environment to make it more suitable. An alpha's semen is probably not absurd amounts of sperm but rather slightly elevated levels of sperm and a crap ton of fluids geared towards protecting sperm, whether that be through neutralizing an acidic environment or suppressing the immune system of an omega.

(Fun aside: if alphas have naturally (and safely) enlarged prostates to produce all this semen I bet they'd get a real kick out of being penetrated during sex. Yes, what I am saying is more alphas should be bottoming/penetrated. Give me all the fics of alphas getting fucked)

This huge quantity of semen might also explain why alphas smell bad to most people except their chemically addicted mates. Cadaverine, putrescine, and spermine are all present in semen and they smell terrible. Cadaverine and putrescine don't even sound like nice smelling words, do they? Well they aren't. Those are the two chemicals that are predominately responsible for things smelling like rotting death. And spermine gives things that...well...semen smell. So potentially alpha semen has elevated levels of cadaverine, putrescine, and spermine and since a/b/o worlds are very heavily based in scent it's quite possible that a/b/o creatures are able to smell this increase.

But why would alphas want to smell like come covered rotting death? Well, it might be used as a sort of 'back off' smell to other alphas or for marking a territory or mate (come marking is a rather frequent behaviour in a/b/o whether it's tagged or not) but it may have a more insidious purpose as well. Cadaverine, putrescine, and spermine poisoning would actually produce a lot of desired behaviours in omegas as far as alphas are concerned.

Poisoning from cadaverine, putrescine, and spermine results in paralysis, fainting, lack of concentration, dizziness, and a cold sensation from a sudden drop in blood pressure. There are other symptoms but these are the important symptoms that would be beneficial to alphas. An omega that is paralyzed or has fainted can't get away, which means it will be there for future mating. An omega that can't concentrate or is too dizzy to move won't be able to communicate their desire to stop or launch an effort to get away during mating. An in heat omega that associates alphas with feeling cool is more likely to actively seek the alpha out to get the desired cooling effect.

These side effects from alpha semen are generally more often seen in fics that engage in come feeding omegas (and they're often well known effects in these worlds) but they are all widely used to describe the after effects of omega/alpha heat sex. However the effects aren't usually described as paralysis and lack of concentration in fics but rather as omega's feeling drunk or like their bones have turned to jelly after sex, an omega can't concentrate and doesn't feel like they can move, omegas often pass out after the alpha ejaculates. It could be really good sex but it also could be mild poisoning. Essentially alpha semen might be the ultimate all natural date rape drug in a/b/o worlds.


Alpha Sperm: Heat Resistance

While female alphas with penises may or may not have a retract-o-cock they almost universally have internally located testicles. This might actually be beneficial rather than hindering because the evolution of female alphas might be why alphas are so successful at impregnating omegas in heat.

It's true that in humans sperm can't survive long at body temperature but that is not true for all mammals. Whales, dolphins, sloths, armadillos, anteaters, and elephants (among others) all have internal testicles and get along fine. It's very possible that female alphas have slowly developed sperm tolerant to higher temperatures. This would come in handy when trying to impregnate an omega in heat since they are quite literally hot.

How would this come about? Simple genetic mutation and time. The only sperm a female alpha could pass along would be sperm that had managed to survive an elevated temperature. Given generations for selecting better and better heat tolerant sperm eventually you would have sperm that easily survive body temperature and would stand a fighting chance at surviving the increased body temperature of an omega in heat.

And fear not, this would spread easily through the male portion of alphas too if you go with my concept of four sex chromosomes. A female alpha would be passing on heat tolerant sperm on the A chromosome meaning that all alphas would carry this trait (and even some betas to a certain degree).


Predatory Chase Drive

Predatory chase drive (or prey drive or chase response) is something people talk about most frequently in relation to canines. Considering a/b/o has origins in werewolf AUs it seems like a natural thing to include since we're already including outdated research on wolf social hierarchies and bulbus glands. So what is it? Well, it's what it sounds like, the drive to chase prey.

Not always, but quite frequently alphas are shown to have a rather strong chase response far beyond what betas or omegas appear to have. This could imply that alphas fulfilled the function of hunter more often than betas or omegas did in their early history or it could be that they favoured physically overcoming prey rather than thinking up strategies since they are generally bigger, stronger, and faster than betas or omegas. These two options could fit two different tropes; alphas are big dumb predators or alphas are cunning providers.

From the big dumb predator view point, only the strongest and fastest alphas would have successfully taken down prey and survived to see another day. This trope implies that they traded off complex problem solving for physical power and so the chase response developed instead, think of it as compensation for a lack of problem solving skills. In this case alphas are the brute force while betas or omegas are the brains of the operation. 

The alphas are cunning providers trope means that alphas developed a chase drive because only alphas were hunting. This trope implies that betas and omegas never had a chance to develop serious prey drives or simply weren't inclined towards it and that the job of hunting fell almost solely to alpha hands. In this case alphas are the brute force and the brains and the chase drive evolved as a specialized tool to be a better provider.

Unfortunately a lot of fics that mention the predatory chase drive tend to go with alphas being big dumb predators that often can't tell if what they're chasing is prey or a mate. This usually has negative outcomes for potential mates and is what many of the more violent sexual and stalking tropes appear to be rooted in.

The moral of the story: never run from an alpha. You will probably trigger their hunting instincts and get mauled.


Possessive Jerks

Alphas exhibit extreme amounts of possessive guarding behaviour towards their mates and territory. You see this most frequently in how alphas tend to say "Mine!" during sex but it's also in all the omegas are slaves tropes where an omega quite literally belongs to an alpha.

Alphas do a lot to keep omegas locked up and away from other alphas. They are generally very serious about keeping other alphas away from their omega(s) and/or mate(s). And it's generally accepted that no alpha can be trusted with another alpha's omega so guarding behaviour becomes an obsessive necessity.

But alphas aren't just getting their kicks out of a strange socially accepted variety of sexual slavery, this type of guarding behaviour is likely the result of a direct attempt at assuring paternity. An alpha that more successfully guards their mate is more likely to be the father of any children conceived.

This trope works on two points. One, that omegas are promiscuous, and thus can't be trusted to not seek out extra-pair matings. An alpha has to ensure that an omega doesn't slip away to mate with someone else and so, is very possessive. And two, alphas are protecting against competitors (alphas, beta males, and omega males). Attacking and driving off competitors for their mate helps to ensure that they don't end up raising the milkman's kids.  


Mysterious Female Alphas

(this is where the crappy anatomy drawings are hiding)

There are four major camps these days when it comes to female alphas: external penis and fertile, retract-o-penis and fertile, no penis with a "reverse knot" and fertile, or anatomically human female genitals but sterile. There are, of course, versions of the above where the genital make up and fertility are swapped but generally speaking this is what you find.

The simplest version, the sterile female alphas with plain old human looking and acting vaginas, tends to portray female alphas as freaks of nature and generally as failures at being women since they cannot conceive. They tend to be outcasts.

As far as anatomy goes, there isn't much special going on here. Google human female reproductive tract and you have this version of a female alpha. This is, unfortunately, a very predominate version of the female alpha.

The no penis with a "reverse knot" female alpha has been seeing a rise in popularity. These female alphas are usually fertile but are only able to carry children, not father them (the lack of a penis being the main obstacle on that part). They appear to be more generally accepted in society in fics and tend to be less aggressive than male alphas. If anything they act much more like betas than they do alphas. If they are in a relationship it's almost always with a male alpha, they tend to be a power couple.

But the social aspect is probably not what you were reading for. So let's get to it, what does a "reverse knot" look like? Probably something like this:

reverse knot

(oh, hey, I drew a butt cheek on this one)

As you can see the "reverse knot" is not really a knot per se, instead it's a band of muscle around the inside of the vagina that grabs onto a penis and doesn't let it go until some amount of time has passed (fics are vague as to how long a "reverse knot" will hold onto a penis). It's simple and unobtrusive and doesn't give a female alpha any "male" traits.

Now the retract-o-penis female alphas also look simple and unobtrusive but only in their un-aroused state. They may be described as having what appears to be an enlarged clitoris but joke's on you. A retract-o-penis female alpha doesn't usually have a clitoris. Instead she has hidden penis.

internal penis

(Can retract-o-penis female alphas pee standing up?)

The penis is located internally along with the testicles. The head of the flaccid penis is located where the clitoris would be. Upon arousal the penis slides out and becomes erect. I drew the testicles as being located above the penis in this case mostly because I thought there wouldn't be a hell of a lot of room between the penis and the vagina but conceivably you could shuffle them in there if your female alphas aren't producing impressive amounts of semen.

These female alphas tend to produce viable sperm but may carry children as well. These female alphas act more like alphas though they tend not to be as aggressive as male alphas. These tend to be the female alphas paired up with female omegas or female betas but still somewhat frequently with male alphas and occasionally male betas.

The last major type of female alpha is the female alpha with an external penis.

external penis

(this is my favourite type of female alpha)

As you can see, she lets it all hang out- except for the testicles. Almost all fics agree that female alphas have internal testicles if they have penises.

These female alphas are almost identical in reproductive organ and genital setup as male omegas, including the nifty fact that vaginal sex would also lead to prostate stimulation.

This type of female alpha functions exactly like a male alpha. They are also the most likely to act like a stereotypical alpha.

These female alphas are the least likely to be paired with male alphas or male betas and the most likely to be paired with other female alphas, female betas, and female omegas. Very occasionally are they paired with male omegas but if any female alpha is going to have a male omega mate it's this one.


Question Time!

Alphas are almost universally described as having huge dicks, in length and girth. Why is there not more autofellatio in a/b/o worlds? Alphas could totally do it. It seems odd that slash writers are dropping the ball on this point.


Chapter Text

What to say about betas? Well, when people describe betas it's generally agreed that they're clean, tidy, and organized. They're levelheaded caretakers. They're often considered to be good followers in pack situations and generally subservient to alphas. They're cautious and avoid risks. They aren't often gifted with the physical super powers of the omega and alpha fertility gods but they do usually make up the bulk of the population (except when they don't). From this description you'd think betas get along by virtue of being patient and playing the long game.

So betas: tidy organized followers who live their lives by keeping their heads down. That sounds like a really boring plain individual over all but betas are actually kind of weird and very probably how the species survives. Betas (like so many other aspects of a/b/o) suffer from this really strange phenomenon where fandom says Thing A is TRUE but then when writing no one really seems to actually do Thing A. So let us deconstruct fandom folk wisdom vs what's actually written about betas.


Beta Only Altruism is a Crock of Shit

It's generally accepted as 'common sense' that betas fulfill the role of selfless babysitters and caretakers; that they succeed in large part through inclusive fitness and kin altruism. However that's not what fics actually show despite how fandom talks about betas.

Let's get those definitions out of the way. The quick and dirty definition of inclusive fitness is supporting the reproduction of similar genes regardless of whether the offspring carrying those genes are yours. Kin altruism is a part of inclusive fitness, simply put you invest in your sibling's offspring because they share genetic material.

That seems counter intuitive to passing on your own genes but it is actually a game of numbers. We're going to segue here a bit so you understand why people say this is how betas work (and then I'm gonna explain why it's bullshit).

Let us say there are two beta sisters. The first beta sister, we'll call her B1, has a beta child while the second beta sister, B2, has an alpha child. B1 should be equally invested in or more so in B2's alpha child. Why? Because betas have fewer children. The offspring of B1 might only have one child. This grandchild will only be 25% related to B1. Whereas alphas generally have many children. The alpha niece/nephew is more likely to go on to have 3+ children. From the point of view of inclusive fitness it's better to have four grand nieces/nephews that collectively share 50% of your genes than it is to have one grandchild that shares only 25% of your genes.

It's in this way that it's commonly agreed upon that betas are more concerned with the survival of a larger family unit rather than with themselves or their direct offspring. The only problem with that is, well... just about everything.

In a/b/o worlds that are more "pack oriented" (generally werewolf au fics) betas are indeed far more invested in the family unit rather than themselves or any one individual but that can also be said of most alphas and omegas in these packs. Pack oriented inclusive fitness isn't unique to betas in these worlds.

Members of a pack in a pack oriented fic are all equally concerned about the survival of their pack. In these pack fics every member of the pack usually participates in cooperative breeding (think, 'it takes a village' style of raising children). All children are collectively cared for and guarded. If there is a threat to the nursery/den adults don't separate their children out to guard specifically. The adults collectively guard all the children. It isn't beta specific behaviour. Alphas will also guard a pack's children and are often the most aggressive about protecting the pack's offspring or other vulnerable members. And while omegas are not usually thought of as aggressive they are often shown viciously protecting a pack's children (or their younger siblings) as a last line of defense.

Pack fics make kin altruism and inclusive fitness the norm for everyone, not just betas.

Fics that are not "pack oriented" should be where we see this beta only inclusive fitness. The thing is, we don't. Betas generally have their own children that they invest in rather than the children of their siblings or extended families (excluding the sterile beta trope but we'll cover that further down). Betas are only heavily invested in their sibling's offspring if they themselves have no children. The moment a beta has children of its own their investment in their sibling's offspring drops off in favour of their own children.

Even in the example of a sibling having an alpha child, betas in fics don't neglect their own offspring in favour of their sibling's alpha child and they aren't likely to willingly grant the alpha niece/nephew more resources than they do their own beta children. Betas are heavily invested in their own children before the children of their siblings. Some fics go so far as to have betas scheming to put their own children into positions of power by murdering or otherwise disposing the "rightful" alpha heir within an extended family unit. That is pretty much the opposite of kin altruism.

However what we do frequently see is beta parents neglecting their beta or omega children in favour of their one magical alpha child which would imply that beta's don't give a rat's ass about inclusive fitness. A beta could have ten beta and omega children and one alpha child, inclusive fitness would argue that the ten beta and omega children would collectively pass on more related genes than one alpha child is likely to but their alpha child will still be more heavily invested in over the beta or omega children. Consider too that just one omega child would likely produce just as many grandchildren as one alpha child but the omega child would come with the added bonus of 100% certainty of genetic relatedness and yet an alpha child will still be favoured over an omega child.

Betas, in short, are just as big of jackasses as alphas when it comes to social expectations about which children are invested in.  


How to Take Over the World, Part 1: Don't kill your spawn

It's generally agreed that betas make up most of the population. If everything was equal and alphas and omegas were producing children at the same rate as betas there wouldn't be anything strange about betas being the largest population group because of how the genetics work out (assuming you're going with my theory of genetics). But it's also generally agreed that alpha/omega pairs reproduce like rabbits while betas reproduce like elephants. Alphas and omegas have a lot more children than betas do.

So why aren't there way more alphas and omegas in the world? Well, lets face it, alphas and omegas in a pre-modern setting would be shit parents.

Alphas and omegas would be too wrapped up in crazed hormonal drives to adequately take care of their own offspring for anywhere from a couple of weeks a year to about one week every month depending on the frequency of heats/ruts. Plus, raging alphas would be liable to kill their offspring if mistaken for a threat and male omegas often have either very underdeveloped breasts or no breasts; a problem when it comes to feeding a litter of babies. Alphas and omegas are very probably hyper fertile because most of their offspring didn't survive to adulthood in pre-modern settings.

Betas on the other hand would have had a lot of advantages in a pre-modern setting. They have fewer offspring to share resources with, they don't go into a hormonal rage once a month, and the people with a uterus nearly always have well developed breasts. These are all great features when it comes to investing long term in offspring and offspring survivability. It also explains why there aren't a ton of alphas and omegas despite high alpha/omega fertility rates: betas have historically been more successful parents.

This tendency in fics to idolize alpha/omega parents as the ultimate caregivers for children is ironically probably the worst for children even in a modern setting because who is looking after these children during a heat/rut? The answer is usually no one.  

Consider that historical infant mortality in humans has ranged between 30% and 50%. Now think about that in an a/b/o setting. Betas are generally considered to be the most human-like, their children would probably experience a similar infant mortality rate. But alphas and omegas? Well, for any given a/b/o work it's possible that half of all omegas can't adequately breastfeed their young or can't breastfeed them at all. Right away the children of omegas are going to have a higher rate of infant mortality. Now add on the fact that alpha and omega parents would routinely not be capable of watching or providing for their young or may pose a very real danger to their young. The children of alpha/omega couples probably had a much higher rate of infant mortality.

Much of early history for a/b/o probably had alpha/omega couples having many alpha and omega children but with most of them dying while beta/beta (or even beta/alpha and beta/omega) couples had many beta children (and a few alpha or omega children) where most of them survived.  

For example, say that an alpha/omega couple have eight children while a beta/beta couple have four children. The beta/beta couple can reasonably expect two to three of their children to survive into adulthood. In fact the chances that all four would survive wouldn't be outlandish. Whereas for the alpha/omega couple expecting four out of eight children to survive would probably have been overly optimistic. And if the couple is alpha/male omega expecting just one child to survive would be optimistic. The alpha/omega couple would likely see the same number or less children survive into adulthood than a beta/beta couple despite reproducing more often.

Most children that have historically survived into adulthood would probably have been betas. A modern world would be built upon this larger beta population. And despite modern advances that would help the children of alpha/omega couples it would still take some time for a reduction in beta population size because as standard of living/wealth/education goes up overall fertility goes down. So while a modern world would allow breastless male omegas to successfully rear children they probably wouldn't be having more children than the average beta.

Over all any given a/b/o world would probably see more betas being born and surviving infancy.


How to Take Over the World, Part 2: Survival of the most stable

So we've got all these betas being born and surviving infancy in pre-modern settings but let's say the rate of birth for alpha, beta, and omega has evened out. In fact, let's say that between the ages of 0 to 14 there is a perfect 1/3 split in the population. Why wouldn't that perfect 1/3 split continue throughout adulthood? Well, put simply, alphas and omegas are hormonal basket cases.

The rate of death for betas is probably much lower than the rate of death for alphas and omegas. Putting social aspects aside for a moment alphas and omegas would still be at a higher risk of death because they're biological time bombs in comparison to betas. Several times a year alphas and omegas become nearly incapable of higher reasoning while their bodies turn traitor on them, choosing reproductive success over their individual fitness. Ruts and heats probably result in a large number of deaths every year, everything from violence to car accidents to heat strokes.

Many fics comment on alphas and omegas becoming disorientated during a heat or rut to the point that it seems on par with a night of binge drinking. They don't make good choices during this time. They're often not capable of fulfilling basic bodily needs like eating and drinking. The idea of basic hygiene goes right out the window. They often can't tell when they're injured or in danger. In short, alphas and omegas spend a large portion of their lives biologically drunk for all intents and purposes.

(could you imagine the insurance rates an omega or alpha would have to pay on their car? It would probably be outrageous and potentially not even cover them if they're in heat/rut because what insurance company is going to insure someone who is basically inebriated for three to seven days a month? I bet public transit is a big deal in a/b/o worlds)

A beta on the other hand is nearly always capable of complex reasoning. They won't sacrifice their own health in a frenzied fit of breeding or mate guarding. Nor are they subject to dangerous increases in body temperature like an omega in heat and they don't get the triple shot of testosterone that sends alphas into a rage during rut. Translate that into a pre-modern setting and it means betas over all were more likely to be successful hunter/gatherers and more likely to escape predators. In a modern setting it means they're able to go to work, go grocery shopping, look both ways when crossing the street, and not pick fights with random strangers because they looked at them funny.

Risk mitigation is not a bad thing and betas are working that angle like pros.


The Sterile Beta Trope

Okay, first off, if more than 50% of the population is sterile betas your society is going to collapse unless alphas and omegas are having about a dozen kids apiece. If this is the route you're going I hope you're writing an apocalypse dystopian fic. (And if you do, send me the link to your apocalypse dystopian fic).

But let's say your society isn't collapsing and betas make up about 1 to 10 percent of the population. Betas in this case are the genetic anomalies, essentially born without a biological sex as far as a/b/o is concerned. Which is interesting because this very very rarely happens in humans. Most genetic abnormalities along these lines usually result in female type appearances so it's odd that these sterile 'betas' aren't presenting as either sterile omegas or sterile alphas.

The more likely answer is that they are in fact omegas or alphas. More specifically they're probably omegas and alphas that have a genetic abnormality that prevents them from going through puberty. There is a real human condition called Kallmann Syndrome that prevents or stops puberty. An interesting symptom of it: lack of a sense of smell, or a much reduced sense of smell. Which is something betas are usually described as lacking and in this trope actually makes sense.

So, if betas are in fact biological alphas and omegas who are infertile the distinct gender of beta would likely be a cultural designation for anyone who was infertile. 

Chapter Text

Binary sex determination solely on it's own fails to conform to the tropes we see in a/b/o fics where betas are present. However if you're reading an alpha/omega fic and betas do not exist and have never existed then binary sex determination works and is the same as it is for X/Y— or Z/W if you are a chicken. For most all other fics it fails.

A/O Binary Model

We will start with an A/O binary model for sex determination where AA = alpha, OO = omega, and AO = beta. This looks great when you see the numbers at the end (numbers are rounded to the nearest 5th just to make it easier to read) but in practice it clashes with most a/b/o tropes. Assuming anyone can mate with anyone this system creates a population that is about:

  • 30% alpha
  • 30% omega
  • 40% beta

Adjusting for the tendency of omega/omega pairings being non-existent and a world where alpha/alpha and omega/beta pairings are frowned upon it gives us this scenario:

  • 25% alpha
  • 10% omega
  • 65% beta

Both of these look about right for a few different a/b/o tropes (though we're getting high levels of omegas in the first part), except in this scenario alpha/omega always produces 100% betas. Right there we can throw this model out because this is not true for nearly all fics.  Alpha/omega pairs rarely if ever have beta children. Further more if you remove alpha/beta pairings from this than the only pairing producing alpha children are beta/beta couples.

A/B Binary Model

Our next option is an A/B binary model where AA = alpha, AB= omega, and BB = beta. This immediately doesn't fit most fics. Assuming everyone can mate with anyone else the population breaks down as such:

  • 30% alpha
  • 40% omega
  • 30% beta

Straight away this is a problematic scenario. There are more omegas than anything else. When you adjust for the tendency of omega/omega pairs being non-existent and alpha/alpha along with omega/beta being socially frowned upon as the trend the rate of omegas increases:

  • 20% alpha
  • 50% omega
  • 30% beta

Beyond the issue that we now have significantly more omegas than anything else we are also faced with the problem that alpha/beta pairings now produce 100% omegas which is rarely the case in fics. Beta/beta pairings can now not produce anything but betas which, based upon many a/b/o fics, is not the case. Betas do sometimes have alpha or omega children.

O/B Binary Model

Our last option for a binary sex determination system is O/B where OB = alpha, OO = omega, and BB = beta. This gives us these numbers:

  • 40% alpha
  • 30% omega
  • 30% beta

This doesn't fit for the majority of fics since alphas are more numerous than betas but there are quite a few fics that use this scenario so let's give it a pass thus far. Now when we adjust for the usual taboo pairings we get this:

  • 30% alpha
  • 20% omega
  • 50% beta

This seems the most acceptable in terms of conforming to tropes. Alpha/omega pairings produce 50% alphas and 50% omegas. Alpha/beta pairings produce 50% alphas and 50% betas. The issue lies within the beta/omega pairing. Beta/omega pairings now produce 100% alphas. This is not true, or rarely so, in fics. Another issue with this is that if alpha/alpha pairings are allowed they will now produce betas 25% of the time which is also rarely seen in fics. Alpha/alpha pairings tend to create more alphas or omegas but never (or rarely) betas.


While some binary sex determination models produce percentages that appear to work upon further investigation they fail to conform to the tropes used in fics and can be uniformly discarded in any instance where betas exist.

Chapter Text

Often called gammas, deltas, or thetas but really any Greek letter will suffice; this is what happens when an author finds a/b/o too restricting, reductionist, or just plain ridiculous.

Most often these other genders and sexes are a mix of alpha, beta, and omega but there is no clear cut consensus among fandom (yet) that this is a delta or this is a gamma or what have you. These roles are often unique and different to each fic and often times come with an info page so you don't get lost. It's cool from a fake science perspective but can be intimidating from a new reader perspective.

These other Greek letters tend to be played out in two ways, a) the fourth (or more) gender and/or sex is just an everyday aspect of the world or b) they are genderqueer people.



Occasionally a fic that is exploring genderqueer themes and issues will have genderqueer people refer to themselves as a different Greek letter. In these worlds it's often the in world term for genderqueer. It's pulled off with varying degrees of success. I'd suggest doing some research before attempting.



This is different from genderqueer or intersex in that these other Greek letters are often presented in the fic as phenotypical, genotypical, and cisgender; ie, a delta has delta chromosomes, delta genitals, and a delta gender role. What do these other Greek letters look and act like? Pretty much anything you can imagine.

Another way this occasionally plays out is an alpha, beta, or (very rarely) omega has a different gender role than most alphas, betas, or omegas but still a culturally accepted gender role for that biological sex. So, for example, a person with beta type genitals may be culturally expected to fulfill either a beta or theta/delta/etc gender role.

(Personally, I think this second interpretation might be the beginning of a/b/o overlaid on top of a/b/o (it's a/b/o inception!). It's very similar to the idea that you sometimes see in a/b/o that female or male are the biological sexes and that alpha, beta, or omega are genders. But in this case beta, for example, is a biological sex and theta/delta/etc and beta are the genders. I hope one day all six generally accepted biological sexes of a/b/o have half a dozen genders each).

Considering that each gender is already made up of at least two biological sexes this second interpretation is not wildly outlandish. So, perhaps your world has gendered words for different shades of beta (or alpha or omega). Or maybe you want to build a world where it's always been culturally accepted for people to straddle the line between different genders.

For the sake of interest here are a few descriptions of different Greek letters that I have come across but are by no means a complete list and you should totally make up more:

  • Male Alphas who have vaginas up their butts: tends to be a stereotypical alpha in every way except sometimes they go into heat, produce slick, and get pregnant.
  • Female Omegas who have a second vagina up their butts: often hypersexed beyond what is considered 'normal' for an omega. They have two wombs. It's almost always considered dangerous.
  • Betas who go into heat: female betas tend to be treated as slightly more sexually active and 'submissive' while male betas will usually produce slick and may or may not be able to become pregnant.
  • Betas who go into rut: extra aggressive betas who want The Sex right now. They probably don't have knots but sometimes they do. Often considered major rivals to alphas.
  • Omega Males with knots: they're often 'not like all the other omegas' the same way she's 'not like all the other girls'. They're probably social pariahs for having a knot.
  • Female Alphas that go into heat: tends to be a stereotypical alpha in every way except they'll also go into heat, produce slick, and get pregnant.
  • Betas that are 'submissive': generally expected to take on gender roles very similar to omegas.
  • Betas that are 'dominant': generally take on gender roles very similar to alphas. This is often not a good thing.
  • Alphas that are submissive: generally take on gender roles very similar to omegas but sometimes betas. This is almost always not a good thing.
  • Male omegas who have the usual vagina up their butt and a second completely separate vagina: often hypersexed beyond what is considered 'normal' for an omega. They have two wombs. It's almost always considered dangerous but sometimes it's worshiped.

Really, you should make up more.


A Brief Note About Transgender a/b/o People and Other Greek Letters

Very occasionally in fics transgender people are in world referred to as theta/delta/gamma/etc. As to how well that's pulled off, well...a lot of fics leave something to be desired. Because, quite simply, why wouldn't you call a transbeta a transbeta? My suggestion is if you are bound and bent on going this route better examine the terminology you use and why you're using it (and maybe, ya know, just say transbeta instead of gamma).