1 - 20 of 35 Works in Undertale NSFW

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  1. Tags
    Summary

    Frisk tells her story of her adventures through the Underground, from the joyous to the nightmares. Frisk finally believes in happy endings. But are there?
    ~Second Chapter is reeeally long and can probably be skipped as it is just my summary of the story of Undertale~

    Series
    Language:
    English
    Words:
    265,419
    Chapters:
    48/?
    Collections:
    3
    Comments:
    832
    Kudos:
    930
    Bookmarks:
    109
    Hits:
    21626
  2. Tags
    Summary

    In what can only be described as the Parappa The Rapper equivalent to the infamous Giantess Toriel X Asriel: Motherly Fuckery fanfic from the Undertale fandom, Parappa one day finds out, in an urgent phone call from Chop Chop Master Onion, that Katy and Lammy (his big stepsister in this story) have drunkenly fallen asleep together in the Milkcan concert auditorium...and also that the legendary master himself has sent the incredibly dirty-minded Paul Chuck and Prince Fleaswallow as bodyguards...and also that he has a shrink gun.

    What ends up happening from there is anyone's guess (wee, at least, anyone who hasn't read the original Motherly Fuckery before, that is), but what I definitely CAN tell you is that it makes the original MF look absolutely TAME by comparison.

    Have FUN, motherfuckers!

    Language:
    English
    Words:
    19,261
    Chapters:
    6/6
    Collections:
    8
    Comments:
    20
    Kudos:
    19
    Bookmarks:
    1
    Hits:
    9460
  3. Tags
    Summary

    In perhaps one of the absolute weirdest, craziest and funniest video game crossover character-swap parodies (and fanfics in general) ever devised, the rich and colorful world of Undertale meets the batshit-insane, drug-induced and equally colorful worlds of Undertail and Um Jammer Lammy (the genderbent bastard child of Parappa The Rapper) in a story that, just like the original game (in fact, it even retains the same plot), is so fucking insane that by the time you're done with it, you'll have literally no goddamned clue what in the hell you just read. And you are going to love it.

    Starring:
    Alphys as Lammy Lamb
    Undyne as Katy Kat
    Gaster as Master Onion
    Chara as Teriyaki Yoko
    Underfresh Sans as PJ
    Papyrus as Fussenpepper
    Muffet as Kathy Pillar
    Asgore as Chuck
    Asriel as Cathy's babies
    Nice Cream Guy as Puddle
    Toriel as Mooselini
    Gerson as Fleaswallow
    Temmie as Ma-san

    Language:
    English
    Words:
    27,553
    Chapters:
    9/9
    Collections:
    9
    Kudos:
    4
    Hits:
    468
  4. Tags
    Summary

    In this simply ingenious and often utterly hilarious political fanfiction satire of epic proportions that is pretty much literally Undertale meets How The Grinch Stole Christmas meets Hillary Clinton VS Donald Trump meets Drawn Together, Alphys decides she's officially gotten sick of the Underground's corrupt monarchy system and therefore additionally decides to team up with Undyne so that the two of them can fraudulently work together toward a common goal of changing their land's system of politics into a presidency...

    with said presidency's very first election being based off of the absolute WORST presidential election campaign in all of recorded USA history. I mean, seriously, what could POSSIBLY go wrong with such an absolutely brilliant plan as this?

    Language:
    English
    Words:
    22,805
    Chapters:
    6/6
    Collections:
    10
    Comments:
    6
    Kudos:
    5
    Hits:
    884
  5. Tags
    Summary

    Oh man, this freaking Alphys X Francis (Alphrancis) shipping...I honestly never thought I'd see it absolutely take off like this, but now...well, here we are, and I honestly couldn't be happier about it.

    To make an incredibly long story short, if you ever wanted to see some hot steamy action between (and just generally involving) these two in a romantic relationship together, then this is undeniably your best, funniest, and hopefully only bet.

    Enjoy, readers! And by "enjoy", I mean "masturbate" XD

    Starring:
    Alphys and a whole bunch of other characters from Undertale
    Francis from Super Paper Mario

    Language:
    English
    Words:
    34,864
    Chapters:
    10/10
    Collections:
    10
    Kudos:
    7
    Hits:
    1900
  6. Tags
    Summary

    In a short but sweet little tie-in to the classic Alphys' Bad School Day that can really only be aptly described as the absolute kinkiest shit to ever come out of the Undertale fandom, Asriel and Alphys and friends return to MTT Middle School for National Barefoot Day...with foot-fetish-inducing chips implanted firmly into their poor little brains by Gaster so that the sick nasty fuck can jerk off to it...yeah, I think you can already see where this is going.

    Language:
    English
    Words:
    18,215
    Chapters:
    6/6
    Collections:
    10
    Comments:
    11
    Kudos:
    19
    Bookmarks:
    1
    Hits:
    1756
  7. Tags
    Summary

    In this hilariously twisted and shockingly well-executed Undertale parody of the classic 1999 animated-film masterpiece The Iron Giant, Alphys and Undyne (both playing the role of Hogarth) stumble upon a giant alien robot from another planet named Mettaton (obviously playing the role of the titular Iron Giant); needless to say, all kinds of hilarity, mischief and surprisingly dark humor ensues as the military progressively gets more and more involved in their awkward predicament.

    Language:
    English
    Words:
    39,655
    Chapters:
    17/17
    Collections:
    11
    Kudos:
    4
    Hits:
    525
  8. Tags
    Summary

    In what is quite easily the single most fucked-up (and probably saddest) Undertale fanfic so far, Flowey goes inside Alphys' head and takes control over her brain, eagerly seeking his revenge for what Alphys did to him and his mother in the previous stories Motherly Fuckery and Incestual Apocalypse.

    How, you may ask? Why, only by doing infinitely WORSE things to HER in return, of course, including but not limited to making her actively destroy everything she loves and holds dear to her and quite literally torturing her to freaking DEATH!

    You know, for KIDS!

    Language:
    English
    Words:
    14,875
    Chapters:
    2/2
    Collections:
    6
    Comments:
    4
    Kudos:
    5
    Hits:
    2750
  9. Tags
    Summary

    In quite possibly the funniest (and, in a lot of ways, the craziest) fanfic to hit the Undertale fandom yet, Alphys goes through her first day of middle school and meets all of her incredibly colorful new friends...

    which sounds like an incredibly boring and mundane idea for a fanfic, until you actually READ all of the crazy shit that ends up happening at nothing short of lightning-fast pace in the process!

    I'm not even going to spoil the things that end up happening here; just read them for yourself. (Well, okay, perhaps I WILL spoil that one part with Alphys and Mettaton playing the electoral roles of Hillary Clinton and Donald Trump...)

    Language:
    English
    Words:
    23,856
    Chapters:
    8/8
    Collections:
    10
    Kudos:
    10
    Bookmarks:
    1
    Hits:
    795
  10. Tags
    Summary

    In a no-less-than-pitch-perfect Undertale parody/remake of an already-hilarious episode from the beloved Nickelodeon classic Rocko's Modern Life, Alphys gets publicly filmed doing a wide variety of rather embarrassing (and often cute/romantic) on video camera by Undyne and Papyrus, with the weak excuse on their part that it's "for her parents."

    Needless to say, all kinds of smuttily extreme romantic fluff, saitirical commentary and hilarious insanity ensue in the process.

    Language:
    English
    Words:
    13,898
    Chapters:
    7/7
    Collections:
    13
    Comments:
    4
    Kudos:
    4
    Hits:
    487
  11. Tags
    Summary

    One day in the quiet, peaceful underground world of Undertale, Alphys has a sick, nasty foot fetish and is too afraid to admit it.

    Yup, that's pretty much all you need to know about this story, apart from the fact that she ends up worshipping Undyne's feet about midway through. Enjoy it anyway, while you still can!

    Language:
    English
    Words:
    4,919
    Chapters:
    1/1
    Collections:
    5
    Kudos:
    4
    Bookmarks:
    1
    Hits:
    888
  12. Tags
    Summary

    In quite possibly the sexiest Undertale foot-fetish fanfic ever written, Undyne invites Alphys over to her house and buys her a new pair of thick wool socks with plans of eventually coaxing the adorable lizard girl into letting her touch and lick her sweaty nasty feet. Unfortunately, however, her plan backfires miserably.

    Language:
    English
    Words:
    2,372
    Chapters:
    1/1
    Collections:
    5
    Kudos:
    11
    Bookmarks:
    2
    Hits:
    1195
  13. Tags
    Summary

    In something that the Undertale fandom has most likely been eagerly awaiting for months on end, Alphys gets infected by a slew of ghost-Chara-clone parasites, meaning that Undyne and Papyrus end up having to go inside her body in order to cure her.

    Needless to say, quite a lot of awkwardness and hilarity ensue.

    Language:
    English
    Words:
    6,804
    Chapters:
    1/1
    Collections:
    6
    Kudos:
    7
    Bookmarks:
    1
    Hits:
    1143
  14. Tags
    Summary

    In the official finale to Alphys VS Undyne's incredibly disturbing giantess offshoot series, readers learn just how incredibly fucked-up things can get in it as Alphys, who has been rendered completely insane by the events of the previous installment, invades Toriel's brain in just about THE most painful way possible without killing her, then mind-controlls her into brutally raping her own family in just about every single way possible...

    prompting said son and husband to then begin violently raping HER back in retaliation. Seriously, if that's not fucked up, I really don't know what is, to be perfectly honest with you.

    Language:
    English
    Words:
    8,375
    Chapters:
    1/1
    Collections:
    6
    Comments:
    3
    Kudos:
    5
    Hits:
    3191
  15. Tags
    Summary

    In what might actually officially be THE most fucked-up Undertale fanfic of all time, putting even the Alphamalg series to absolute shame, Asriel (after watching quite a bit too much Alphys VS Undyne) decides to reenact the giantess scenes from said television series...only with him and Toriel!

    Needless to say, things get really REALLY fucked-up really REALLY fast. Trust me, the title is literal with this one.

    Language:
    English
    Words:
    9,623
    Chapters:
    1/1
    Collections:
    4
    Comments:
    16
    Kudos:
    19
    Hits:
    15476
  16. Tags
    Summary

    A full compilation of both of the infamous giantess Alphyne scenes from Alphys VS Undyne, featuring everything that you loved to hate about both of them! Featuring such lovely and totally-not-gratuitously-fetishistic moments as:

    * Alphys very seriously threatening to bloodily, violently rip Undyne's brain apart from the inside out with her bare hands

    * Alphys and Undyne taking over each other's brains and publicly humiliating each other for sexual amusement

    * Alphys going down Undyne's diarrhea-spewing intestines like a water slide and being kinkily tickled by her villi in the process

    * Monster/Amalgamate bestiality

    * Undyne worshipping Alphys' brain

    * Alphys and Undyne worshipping each other's massive feet

    * Undyne forcefully shoving Alphys into her womb

    * Undyne picking Alphys' earwax off of the sole of her boot and eating it without even the slightest second thought

    * Alphys licking out the nasty disgusting athlete's-foot fungus growing in the webbing between Undyne's filthy, unwashed toes

    * Undyne puking up Alphys into an already half-full glass of someone else's (namely, Reaper Bird's) vomit

    HAVE FUN, YOU PERVERTED NASTY FREAKSHOWS!

    Language:
    English
    Words:
    9,155
    Chapters:
    2/2
    Collections:
    3
    Comments:
    2
    Kudos:
    11
    Bookmarks:
    2
    Hits:
    3169
  17. Tags
    Summary

    In a sort of role-swapped sequel to the infamous Giantess Alphys X Undyne scene from Chapters 4-6 of Alphys VS Undyne, Undyne shrinks Alphys to nearly microscopic size, allowing the two of them to finally exact their revenge on each other once and for all...using the absolute kinkiest methods imaginable.

    And yes, the brain-infiltration part is also back.

    WARNING: This story is so fucked-up that it actually makes the original scene it was based off of look rather TAME by comparison. Reader discretion and an extremely strong stomach are both very strongly advised; you have been warned.

    Language:
    English
    Words:
    4,883
    Chapters:
    1/1
    Collections:
    3
    Kudos:
    11
    Bookmarks:
    1
    Hits:
    3518
  18. Tags
    Summary

    Essentially the ultimate compilation of Alphys-centric literary fap material for Undertale fans to drool over, this massive collection contains literally everything you could ever want from Undertail smut fanfiction, featuring more fetishes than you can even shake a dick at.

    Featuring:

    Alphamalg: TCDGS - The series that started it all, bringing undisputedly the absolute worst UT shipping of all time into existence. If you ever wanted to see Alphys fuck her own eldritch-abomination pets, let's just say you're in luck.

    Alphys Loves Feet and Tempted By The Feet Of Alphys: If you've got a foot fetish, why not sit and relax here and blow a load off?

    Lemon Fed - If you ever wanted to see a full-on vore scene between Alphys and Lemon Bread, with Alphys serving as the victim...well, you're a little fucked in the head, but why not?

    Giantess Alphys X Undyne: BLAUC - Hailing straight from Chapters 4-6 of the amazingly underrated Alphys VS Undyne fanfic, this scene shows what REALLY happens when Undyne finds a shrink ray and catches Alphys sleeping. Intense body worship and mind-control-induced public humiliation ensue.

    Language:
    English
    Words:
    39,452
    Chapters:
    10/10
    Collections:
    3
    Comments:
    4
    Kudos:
    5
    Hits:
    3064
  19. Tags
    Summary

    In what is undoubtedly one of the funniest Undertale fanfics of all time, Alphys and Undyne settle their ever-growing romantic rivalry in a hilariously wacky series of contests ranging from crack-shipping playdates, tickle torture and singing to verbal wrestling, one-on-one multiplayer ownage, Mario Kart copyright infringement, cartoon intro parodies and even some hot Undyne-on-Alphys giantess action!

    For Alphyne fans looking for some funny, sexy and satirical romantic-comedy stuff to both laugh and occasionally jerk it to, you've officially reached heaven! Enjoy your stay here, pals!

    Language:
    English
    Words:
    11,239
    Chapters:
    7/7
    Collections:
    5
    Comments:
    9
    Kudos:
    14
    Bookmarks:
    3
    Hits:
    2630
  20. Tags
    Summary

    I am accepting requests for anything you want me to write :D

    Language:
    English
    Words:
    27,986
    Chapters:
    4/?
    Collections:
    1
    Comments:
    54
    Kudos:
    126
    Bookmarks:
    9
    Hits:
    3332

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