1 - 20 of 2133 Works in Alternate Universe - Underswap (Undertale)

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  1. Tags
    Summary

    Black and Mutt have a new pet human. But she has powerful family and heaven help those who mess with the De la Cours.

    Language:
    English
    Words:
    662
    Chapters:
    1/?
    Hits:
    0
  2. Tags
    Summary

    You the reader are about to go on an adventure to the underground. You don’t necessarily have a good home life but even so you weren’t expecting what happens to actually change it so drastically! When you come out the other side you weren’t expecting to wake up after your harrowing escape, in the Gaster Brothers home.

    Language:
    English
    Words:
    28,535
    Chapters:
    7/7
    Comments:
    25
    Kudos:
    79
    Bookmarks:
    21
    Hits:
    1711
  3. Tags
    Summary

    You are a lost black cat trying to go home.

    The cold streets are horrible place for a home Kitty cat like you withno 'survival tacttics' it all.

    Hope, thats the thing that weird cat help you keep after appearing from darknees itself.

    "Safety" he promised in change of helping his kittens.

    Language:
    English
    Words:
    16,625
    Chapters:
    6/?
    Comments:
    18
    Kudos:
    34
    Bookmarks:
    6
    Hits:
    675
  4. Tags
    Summary

    A collection drabbles requested from Tumblr and Ao3 comments. NSFW requests will have an addition to the title and a note at the beginning of the chapter for those who would prefer to avoid them. Content will be tagged by chapter.
    My Tumblr: vex-bittys

    Language:
    English
    Words:
    7,818
    Chapters:
    9/?
    Comments:
    52
    Kudos:
    107
    Bookmarks:
    13
    Hits:
    2043
  5. Tags
    Summary

    After Sans had the genius idea to mess with a machine he had created, he didn't expect that it would have brought versions of himself and his two brothers (Papyrus and Wingdings Gaster) to their universe. Nor did he expect that an old friend of his would introduce him to none other than his soulmate, or that his very soulmate was also his brother's and alternate versions' also.

    Language:
    English
    Words:
    35,551
    Chapters:
    12/?
    Comments:
    90
    Kudos:
    101
    Bookmarks:
    27
    Hits:
    1491
  6. Tags
    Summary

    Red moves back home with his tiny tot of a son, owning a book shop and expecting just the normal ins and outs of every day life. An out of towner comes in, and Red only expected a little flirting, maybe some teasing but not a sudden and swift change to everything he's ever known in his life!

    (Based on all Hallmark movies everywhere)

    Series
    Language:
    English
    Words:
    29,536
    Chapters:
    16/?
    Comments:
    210
    Kudos:
    107
    Bookmarks:
    22
    Hits:
    1704
  7. Tags
    Summary

    A mostly Sans-centric, NSFW collection of drabbles from over on my tumblr. Multiple pairings, lots of AUs, kinks abound!

    Language:
    English
    Words:
    38,183
    Chapters:
    44/?
    Comments:
    151
    Kudos:
    656
    Bookmarks:
    69
    Hits:
    17053
  8. Tags
    Summary

    A hundred years after the X Event, and The Omega Timeline is now the heart of the multiverse. The main goal of the place? To ensure that Error never steps foot inside the timeline, or harms anyone living there.

    However, when Error is discovered in the timeline, he is promptly captured, muzzled like a wild animal, and taken to be euthanized. Things start to spiral out of control, and Ink, the once benevolent protector, grows more and more distant. Soon no one is safe, and Error’s life hangs in the balance between those who wish him a tormented existence, and those whose motives are unknown.

    (Feat. Gradient, making extremely poor decisions.)

     

     

    (((Illustrations by Shimokomoriya on DeviantArt. Check them out!!)))
    (((Edited by ShandyCandy278 who is Super Cool™)))

    Language:
    English
    Words:
    109,780
    Chapters:
    21/?
    Comments:
    1570
    Kudos:
    1094
    Bookmarks:
    120
    Hits:
    16393
  9. Tags
    Summary

    The title speaks for itself, does it not?

    ***

    WARNING: MIGHT CONTAIN SCENES THAT TUG YOUR HEART, LANGUAGE, NOT FOR THE FAINT OF HEART, TALK ABOUT TOPICS SENSITIVE TO SOME PEOPLE AND OTHER THINGS.

    READER DISCRETION IS ADVISED.

    Series
    Language:
    English
    Words:
    44,666
    Chapters:
    26/?
    Comments:
    128
    Kudos:
    163
    Bookmarks:
    19
    Hits:
    2916
  10. Tags
    Summary

    Machine broken, Rus finds himself stuck in Underfell while he works on getting it fixed. Until then, he has to deal with Edge, Red's (maybe not so) insufferable brother.

    Language:
    English
    Words:
    19,074
    Chapters:
    6/?
    Comments:
    106
    Kudos:
    114
    Bookmarks:
    18
    Hits:
    874
  11. Tags
    Summary

    A storm scares the crap out of you one night after a loud strike of thunder. Lucky for you, your five wonderful bonefriends are ready and willing to stay with you until it passes, for your sake of course. No way a little thunder would freak them out, heh.

    Language:
    English
    Words:
    31,311
    Chapters:
    9/?
    Comments:
    60
    Kudos:
    145
    Bookmarks:
    18
    Hits:
    2068
  12. Tags
    Summary

    A drunken night you can't remember leads you to wake up in the very large home of a very large family of skeletons. You try to escape their grasp and pretend like nothing ever happened, but for some reason, they're determined to befriend you. Some try to get a little too friendly. Some don't like you at all.

    But when disaster strikes your home and you have nowhere to go, they're more than happy to lend you their dusty attic. You don't even have to pay rent. What's the catch?

    Oh. That. Well you suppose you could do that if it means having a roof over your head.

    Language:
    English
    Words:
    4,930
    Chapters:
    2/?
    Comments:
    17
    Kudos:
    68
    Bookmarks:
    20
    Hits:
    588
  13. Tags
    Summary

    So apparently multi dimensions are a thing, and Mt. Ebott spewed out groups of monsters from different universes. You've basically been adopted by the Fell Clan Alphys and Undyne - Sakura and Scarlet, and, through them, discover that you have a fuckton of Soulmates.

    Who'da thunk?

    Language:
    English
    Words:
    10,086
    Chapters:
    3/?
    Comments:
    66
    Kudos:
    172
    Bookmarks:
    50
    Hits:
    1060
  14. Tags
    Summary

    Monsters have been pouring out of Ebott’s mountain range steadily for the past few years. Apparently spurred by the breaking of the key barrier the great ambassador mage Frisk. Therefore the surrounding towns and cities have been getting a boom of new life. Even saving several from becoming ghost towns. This story takes place in one such town just inside the proclaimed land of monsters.

    Series
    Language:
    English
    Words:
    380
    Chapters:
    1/10
    Hits:
    11
  15. Tags
    Summary

    You find yourself out of a job, on the verge of getting kicked out of your apartment because you can't pay the rent and no where to go. Until your newest skeleton friend suggests you move in with them and their cousins until you get back on your feet again. You didn't expect to like living with this many people at once so much though...

    Language:
    English
    Words:
    185,122
    Chapters:
    44/?
    Comments:
    1010
    Kudos:
    2203
    Bookmarks:
    385
    Hits:
    40946
  16. Tags
    Summary

    ~Ava’s Guide to Invading the Multiverse~
    Step One - Go Fishing

    Language:
    English
    Words:
    234,714
    Chapters:
    89/?
    Comments:
    2230
    Kudos:
    1297
    Bookmarks:
    157
    Hits:
    20292
  17. Tags
    Summary

    Flowers grow, and they wilt.

    That doesn't mean they aren't beautiful.

    Language:
    English
    Words:
    9,742
    Chapters:
    11/?
    Comments:
    36
    Kudos:
    91
    Bookmarks:
    8
    Hits:
    4660
  18. Tags
    Summary

    Fell wants to settle down and have kids with Blueberry, but Red isn't happy about this news. He can't cope with the fact his brother is moving on, so he selfishly goes on one last adventure with Papyrus. A different Papyrus. Stretch.

    Although Stretch is tagging along for his own selfish reasons too. He wants to get a little closer to Red... and the skeleton finally offered to show him around Underfell, so he can't refuse. It's a shame Papyrus is on every Wanted Board in the underground.

    Language:
    English
    Words:
    7,821
    Chapters:
    7/7
    Comments:
    1
    Kudos:
    10
    Hits:
    120
  19. Tags
    Summary

    (Y/n) lost her job, which sucks. If only she hadn't lost her second job, and apartment, as well! Now all she's got is a camper full of her crap on the back of her truck, and nowhere to go. At least she found this campground, even if it is in the middle of nowhere, and looks like no one has been around it for a while, and a skeleton with a head wound tries to make her into a meal... Rough start to making new friends, but his brother is sweet enough!
    And then there's the other skeletons who inhabit the other cabins, who all look vaguely similar... Their explanation of "cousins" only goes so far, but there are more concerning things to worry about, like how almost every skeleton is trying to get into her pants, their heats, and where her clothes, particularly her socks, keep disappearing to?!

    Language:
    English
    Words:
    30,438
    Chapters:
    12/?
    Comments:
    307
    Kudos:
    477
    Bookmarks:
    113
    Hits:
    7401
  20. Tags
    Summary

    You are a former human from our world. One day you suddenly woke up in the Undertale Multiverse.

    As Error Sans.

    Normally this wouldn't have been an issue for you. You've had lot's of practice in avoiding people and dodging unwanted drama. Just stay in the Anti-void and don't get involved with Ink or anything else.

    But there's a problem with that.

    The original Error is missing, and, without him, there's no one around destroying copies of AUs and keeping the balance of the Multiverse from tipping. Naturally you would be most qualified for the job, right? Wrong. You are a pacifist. A Creater. You would rather do anything else than hurt another person. Too bad your code is centered around causing complete and utter destruction.

    Oh yeah, and you may or may not have accidentally "kidnapped" a random Underswap Sans in a impulsive last ditch effort to preserve his collapsing timeline. And it turns out it was not just any Underswap Sans. No, this one is part of curtan group of skeletons you've been trying to avoid.

    The Star Sanses.

    Who are now somehow convinced you have amnesia.

    Shit.

    Language:
    English
    Words:
    1,445
    Chapters:
    1/?
    Comments:
    21
    Kudos:
    103
    Bookmarks:
    23
    Hits:
    323

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