1 - 20 of 2026 Works in Underfell Sans (Undertale)

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  1. Tags
    Summary

    There were a lot of rules Sans was forced to follow in his life. It didn't matter what he thought or how he felt - the important thing was his compliance.

    It had never seemed like a delicate balance. Not until someone who sat next to him in class did the most insane thing he'd ever seen.

    Alphys became his friend.

    Alternate POV: What was happening with Sans and Papyrus?
    MAJOR SPOILERS for "Serif One" so I highly recommend reading that first.

    Series
    Language:
    English
    Words:
    11,132
    Chapters:
    2/?
    Kudos:
    5
    Hits:
    14
  2. Tags
    Summary

    Sans finally got his big break as a comedian and is ready to tour the country with his act. But being the son of a famous scientist with many powerful enemies, Gaster isn't going to let him go alone. He hires his son a bodyguard, another skeleton named Red, whose job it is to keep Sans safe at all costs. But Sans isn't about to make it easy for him.

    Language:
    English
    Words:
    2,400
    Chapters:
    24/?
    Comments:
    168
    Kudos:
    90
    Bookmarks:
    14
    Hits:
    1300
  3. Tags
    Summary

    In order to summon a small version of your Soulmate you need few ingredients: Milk, a Love Bloom flower, a small fragment of your soul and a monster to perform the ritual.

    You wanted to feel less lonely in your apartment.

    You did not expect to find yourself with your hands so full.

    Language:
    English
    Words:
    9,217
    Chapters:
    8/?
    Comments:
    249
    Kudos:
    701
    Bookmarks:
    144
    Hits:
    7741
  4. Tags
    Summary

    You’re overworked and in need of some vacation time. This however was not what you had in mind. Buckle up buttercup, you’re in for one heck of a ride.

     

    Oh, why, hello there! And who might you be? Ah, the reader! Hahaha! How delightful! Will you be joining us on our little- V̷͔̞̹̊͆ả̷͈̫̃͜c̸̛͖͂a̸͈̾͝͝t̷̤̦͑̾̕i̷͖̝̦͛̃͠ỏ̷̻͆n̸̬͎̽͘? Oh, our destination? Yes, of course. You enjoy Undertale do you not? Never mind, no need to answer that. Of course you do. Silly question, my apologies. Well, we mustn’t dawdle, then, come along and enjoy your much deserved V̷͔̞̹̊͆ả̷͈̫̃͜c̸̛͖͂a̸͈̾͝͝t̷̤̦͑̾̕i̷͖̝̦͛̃͠ỏ̷̻͆n̸̬͎̽͘.

    Language:
    English
    Words:
    51,504
    Chapters:
    14/?
    Comments:
    164
    Kudos:
    154
    Bookmarks:
    39
    Hits:
    2259
  5. Tags
    Summary

    Y/N. A skeletal wolf monster who lived as a hunter in Horrortale alongside the Skeleton brothers to help other monsters survive the famine Underground. Human flesh was a delicacy. It was not something she wanted to consume. None of them had a choice. She was feared by many for her ferocious strength and temper. Only the Horror brothers UNDERSTOOD her. They continued to suffer until...
    Their house appeared above ground. Strange skeletons much alike her own skellies seem to want to keep them within the forest due to their hellish appearances. It might be due to fear...and the woman who had them wrapped around their finger. Y/N would not allow them to bully her best friends.

    Language:
    English
    Words:
    14,044
    Chapters:
    11/?
    Comments:
    32
    Kudos:
    194
    Bookmarks:
    37
    Hits:
    2641
  6. Tags
    Summary

    Red, Edge’s brother, had been hiding away in the lab recently, messing with some sort of machine that he didn’t seem eager to tell Edge about. Edge, obviously, didn’t plan on letting this slide. 

    After yet another day of Red blocking himself in, Edge decided that he would put a stop to it.

    By breaking the door down. And nagging him, not letting Red get a word in, as he stepped closer to inspect this machine that Red kept hidden.

    “WHAT EVEN IS THIS, ANYWAYS? WHAT MAKES IT SO IMPORTANT-”

    There was a click, a snap, and a whir.

    And then Edge was gone in a flash of light.

    Series
    Language:
    English
    Words:
    11,533
    Chapters:
    5/?
    Comments:
    20
    Kudos:
    30
    Bookmarks:
    2
    Hits:
    298
  7. Tags
    Summary

    Red has lived with his brother, Edge, for years at their newest foster home. He's made a few friends, ones he sees on the regular. And he's told Undyne and Alphys that they can bring over friends of their own anytime they want. They'd never taken him up on that offer before.

    Now, Alphys comes over with a new friend. His name is Sans.

    He's weird. Red doesn't mind, but when Sans runs out in the middle of movie night it raises some red flags. Is Sans okay? Probably not. But is it Red's place to care?

    VERY alternate of an AU: Monsters were never Underground, and the social dynamics are totally different. It's literally so AU it's practically an original work with the same characters. Oops.

    If you came here from my other fic, One Step Back, this is NOTHING LIKE THAT ONE. Well, maybe a little, but not enough for that to be a good comparison for whether you'll like this or not. This one gets darker. A lot darker.

    Series
    Language:
    English
    Words:
    103,725
    Chapters:
    26/26
    Comments:
    43
    Kudos:
    46
    Bookmarks:
    7
    Hits:
    446
  8. Tags
    Summary

    The new leader of the Star Sans’s, Dream tries everything in his power to save his brother Nightmare.

    His latest plan involves a vial Lust serum from Underlust and a concealed syringe. It doesn’t go the way Dream hopes.

    (Eventual Killermare smut)

    Language:
    English
    Words:
    18,664
    Chapters:
    7/?
    Comments:
    46
    Kudos:
    83
    Bookmarks:
    7
    Hits:
    1137
  9. Tags
    Summary

    You're an afab trans non-binary man, who pays the bills by being a faceless "accountant" online.

    one day, you're supposed to meet friends for dinner and bump into a skeleton. little did you know the chaos that would unfold just by greeting one!

    well...at least you can say your biggest fans are definitely big...*wink*

     

    reader is a afro-latino non-binary trans man.

    Language:
    English
    Words:
    587
    Chapters:
    1/1
    Comments:
    3
    Kudos:
    12
    Bookmarks:
    2
    Hits:
    115
  10. Tags
    Summary

    What's the point of falling in love if at any moment your world can be reset and everything ripped away? That's how Red feels, anyway.

    Language:
    English
    Words:
    37,155
    Chapters:
    13/?
    Comments:
    133
    Kudos:
    129
    Bookmarks:
    19
    Hits:
    2559
  11. Tags
    Summary

    [Y/N] [L/N]. A 23-year-old woman known for her intelligence in the field of science and monster history. Ever since she was five years old, she has been known as a genius, someone who could make the world a better place. Of course, monsters have always intrigued her, so she is pleased when they appear from Mt. Ebott. With a family who question her own intelligence and authority, who knows what the future has to bring? Then again, why should she care?

    Language:
    English
    Words:
    14,844
    Chapters:
    12/?
    Comments:
    27
    Kudos:
    119
    Bookmarks:
    34
    Hits:
    1960
  12. Tags
    Summary

    Congratulations!!

    You're one of the 'Lucky' few to get your hands on a copy of Broken Souls! It's a once in a lifetime opportunity to play with our 'Immersive' technology!!

    Create a Unique character! Meet Interesting Characters! Fall in Love! Unlock Secretes, and Much, Much More!

    Warning!!

    We are not Liable for any harmed caused! Have fun, stay safe, but most importantly!

    Don't. Die.

    Language:
    English
    Words:
    113,441
    Chapters:
    23/?
    Comments:
    620
    Kudos:
    508
    Bookmarks:
    109
    Hits:
    11678
  13. Tags
    Summary

    Just a space to keep all the canon info about this AU.

    Series
    Language:
    English
    Words:
    479
    Chapters:
    2/?
    Hits:
    4
  14. Tags
    Summary

    Four AU’s have come to a happy ending on the surface. It is a new beginning for everyone, but Berry is haunted by his past that still clings to him and threatens to pull him back into the darkness, unknown to his now growing skeleton family. The newest skeletons are from the last set that surfaced: Fellswap. They are not going to let Berry be taken. Howl and Daemon, the two newest skeletons, have to dig into a horrible truth and show the world Berry’s past, and with the help of their fellow skeletons, they hope to make a better future for him and all other monsters.

    This is adapted from a role play with GetMcDunkedOn and me (Diyami). I hope you enjoy it.

    Series
    Language:
    English
    Words:
    226,361
    Chapters:
    35/?
    Comments:
    648
    Kudos:
    246
    Bookmarks:
    41
    Hits:
    8093
  15. Tags
    Summary

    what if the multiverse restarts and nobody remembers anything unless there's one that remembers

    sorry I'm not very good with summary, this is the first story I do so if it doesn't look very good and because I'm still trained. but I hope you like it.

    Series
    Language:
    English
    Words:
    1,293
    Chapters:
    4/?
    Comments:
    1
    Kudos:
    23
    Hits:
    276
  16. Tags
    Summary

    It's been months since you've seen Red, your ex. Now he's back on your doorstep. The kicker?

    Your boyfriend is home.

    Series
    Language:
    English
    Words:
    1,155
    Chapters:
    1/1
    Comments:
    19
    Kudos:
    54
    Bookmarks:
    6
    Hits:
    518
  17. Tags
    Summary

    What... Happened? (Y/N), is a girl that wakes up in a hospital not knowing where she is, she was told to have amnesia over something that happened years ago that made her go into a coma for 5 years. Later, she inherits a little house, when she goes in she finds a note with a necklace that gives her strange abilities saying that she has to recover her memories a certain way because a disastrous event is coming and it’s up to her to save the multiverse. Will she be able to do it? And what surprises await her?

    Language:
    English
    Words:
    30,821
    Chapters:
    13/?
    Comments:
    9
    Kudos:
    31
    Bookmarks:
    11
    Hits:
    949
  18. Tags
    Summary

    It's been 5 year since you and your brother fell into the Underground. You had lived with Sans and Papyrus during this time. Just before you two had arrived, a human had fallen, killed the king and left with the monsters' one means of escaping, further trapping them. At first, there wasn't much except a new queen being announced. She had made it law that any human that were to fall down were to be killed on sight . Good thing you and your brother weren't human.

    Years passed and slowly everyone was running out of food and options, it was during this time that another human fell down and died in the woods of Snowdin, it was also during this time that your species was revealed, but they were okay with the face that you had to eat the flesh of humans, not like they were any better. Then it marked your 5th year in the Underground when suddenly, everything went black while check the traps with Papyrus.

    Language:
    English
    Words:
    1,557
    Chapters:
    1/?
    Comments:
    3
    Kudos:
    36
    Bookmarks:
    10
    Hits:
    183
  19. Tags
    Summary

    Your in the woods, it's hard to move, your starving, weak and cold and your getting random flashbacks about someone with fleshy hands? Is that you?

    And whose this random voice whose helping you out?

     

    Best to find shelter
     

     

    (Slow updates)

    Language:
    English
    Words:
    10,213
    Chapters:
    3/?
    Comments:
    37
    Kudos:
    183
    Bookmarks:
    43
    Hits:
    1379
  20. Tags
    Summary

    As a group of Underfell refugees make it to the surface they are lucky enough to be offered a place to stay temporarily. However not everything starts out so well on the surface for the group. Will they be able to adapt to life on the surface or will things end up too much for them? Will the humans even accept them on the surface and let them live in peace alongside them?

    Language:
    English
    Words:
    12,511
    Chapters:
    1/1
    Bookmarks:
    1
    Hits:
    31

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