1 - 20 of 4,386 Works in Alternate Universe - Underfell (Undertale)
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Wake up buried in snow, alone, and with no memories?
Check.Keep seeing numbers, words, and random text floating around every object and surface as far as the eye can see?
Also check.Why does every person he meets say he needs help?!
He’s perfectly fine, if you ask him.“I wonder what determination tastes like.”
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Note from the author:
This is my take on Fatal Error — a much more non-canon,[this isn’t even OOC, this is just straight-up a different person with the same name]
amnesiac version of him.
He’s also not fully canon-compliant in terms of power scaling and may even have a different origin and and backstory.It’s my reimagining of him with a completly diffrent story.
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Stretch has been your best friend since you two were children. Ever since you first introduced yourself to him, he's felt this pull towards you, and you can feel it too. The two of you have been harboring crushes for so long, will either of you ever confess?
Blue didn't really know what the machine in the basement did, it was his late father's old project. When drunken mistake causes this dormant machine to suddenly spit out skeletons who look eerily similar to him and his little brother, how will they deal with their counterparts in a foreign world?
Act 1: Flowers Waiting to Bloom (Chapter 1-20)
Act 2: Fields of Flowers (Chapter 21 - 38)
Act 3: Petals in the Wind (Chapter 39 - 45)Series
- Part 1 of Forget Me Not
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You ended it all one fateful night, but instead of dying, were swept up in a world of war with a bundle of a skeleton in your arms. With a crazy scientists chasing you for something you don’t even remember doing, figuring out how to escape with your little brother still alive, a life that isn’t quite yours, lots of angst, and even more comfort… this will be quite the wild ride.
Now including a skeleton-house that is becoming VERY concerned for your mental wellbeing, (buried after the much-needed war-trauma,) you have to deal with a whole ‘nother group of wacky skeletons judging you. AGAIN.But… in order to have the best comfort fic, you sometimes need to have the worst angst beforehand.
Or, as Gaster once said… you need to break a few eggs in order to make an omelette. :]
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You honestly can't remember when you had officially moved into the lodge to be with your datemate. It started as leaving things in his room under the (flimsy) excuse of having stuff for the next time you have an impromptu sleepover—but it was a not-so-subtle takeover.
The others didn't mind it either and were gracious enough to provide you with your own room for when everyone's shenanigans prove to be too much for you, but little did they know that they practically invited the devil herself into their home, because you're the queen of starting some bullshit or doing things for the bit.
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You are suuuper obsessed with Galaxy and its thing, especially the universe! You spend over Years building a machine and another over years to make it perfect, night and day, even when you're sick, you still do the things you love.
You close your eyes and ears to the people who call you crazy, calling you mad, insulting your creation, Etc. Etc.
But who are they to stop you anyway??And dear god, after years of tears, blood, and mind... the MACHINE IS PERFECT! At least that was what you thought.
You get sucked by your own creation when you try to make coordination and testing on it, and now you're here.. with a skeleton.. oh my god
It's wonderful! YOUR MACHINE IS WORKING! HAH! You can't wait to slap the mouth that calls your creation useless by this INVENTION~
Well, after you successfully back to your own universe, survive on this world, well, you're gonna get help from the skeletons infront of you... right?
And then you can ask a few questions about this universe, hopefully he wants to answer them... he will... You're going to make sure he gonna help you, if it means begging.
Alright... here we go.
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FallenSouls [Frozen Soul Fell AU] by himejoshinashatra
Fandoms: Frozen Soul [DG] (Roblox)
10 Dec 2025
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Frozen Soul but everyone's edgy, wears black, and swears a ton.
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make no mistake, that's what he heard. Frisk had fallen down into a hostile world, what appeared to be out to get him. then there was a human, one who hated her species with a burning passion. but will an encounter of the two change that? and what else will happen with Frisk's adventures?
Series
- Part 1 of My Undertale AU Stuff
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You and your family are just enjoying a nice day at the park, when a life changing event happens that ruins everything.
You get taken away to a facility to be tested on...
Life doesn't feel as peaceful as it once did, you hated your new life.
"I wish I could just go into those story books I used to read..."
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If Angels Have Halos Do Skeletons Do To? by Tiddlywinks9
Fandoms: Undertale (Video Game)
07 Dec 2025
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After three years of dating you find yourself pregnant with Sans' child. You find yourself alone as Sans dumps you not believing the child is his. Managing single motherhood and a job at the flower shop you find love once again with another skeleton in a orange hoodie who strangely looks like your Ex's brother
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For as long as you remember, you've only known nothing but cold and the feeling of worthlessness. You once had a source of light in the dark but it no longer exists. Will you find it again with your clouded thoughts and memories? Or will you succumb to the rising waters and drown?
In which, you are an AU sans with severe depression, self worth issues and hazy memories of yourself—just wanting to go home…
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So I've seen someone else do this and asked myself, why not? I have loads of ideas/situations for fanfics yet have no time to write them or I end up just procrastinating for two years after posting the first chapter (if you're looking at my other fanfic no you aren't). So here goes nothing I guess.
Some will be longer than others, some I might expand on and make multiple chapters, but I don't think I'll make them into full fanfics. Some will have more oc's or more lore/backstory and some won't have any. Some will be about specific skeletons, others will be about all of them. There will be different tropes, jobs and personalities for Reader, and I might make them into a bit of a self-insert sometimes.
Again, if anyone likes any of these, please feel free to use them! But do tell me, mostly to read the end result ;)
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You wake up in an empty room, you can't remember who you are or how you end up here, all you know is that you need to leave this place. Your first encounter being a pair of skeleton brothers that seem both too nice and scary, you wonder what's the deal with this place but does it really matter? the place is full of strange creatures, what would you do?
There's no place for someone like you in a place like this.
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Unavoidable Outcomes by Crystalight532
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
07 Dec 2025
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The Multiverse isn't as unreachable as one might think. Sometimes, all it takes is one aware person to tip the scales for another to find out about it. But when one isn't ready for it, returning to their own world is relieving and best for the psyche.
Humanity's thirst for knowledge is near insatiable. How far would they be willing to go to learn more about their new magical coinhabitants on the surface? How far would they go if they could weaponise their magic?
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After the events of Multiverse Madness, with Shattered and Reality now back in their own multiverse, the fighting is quick to once again break out. Reality explores and learns about his multiverse and the damage Shattered has done to it and attempts to save it, while Shattered continues his efforts to stop Reality and get him encased in stone again. The two of them make allies and enemies, Reality making friends and becoming part of a found family while Shattered follows in Nightmare's footsteps and manipulates his allies into thinking he cares for them. Traumas are experienced, friendships are strained, loyalties are tested, and deaths are witnessed and grieved for. It's an emotional rollercoaster, so be prepared for what happens, as it's not for the faint of heart.
Discord server: https://discord.gg/wQfvxyEuvj
Tumblr in case you guys want to make fanart: https://www.tumblr.com/werecat1234
Shoutout to my beta readers Ali, Rain, Iluvdragons, Prophet, Poki, Clichély, Nova, and Note of Joy! You guys are awesome! Thank you guys so much for beta reading this for me and giving me feedback on the story, you have no idea how much it truly does help!
Series
- Part 4 of Werecat's UTAU Megaverse
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Life is monotonous and dull, but it’s okay. You’re fine.
Assignment after assignment, test after test, meaningless conversation after meaningless conversation. It fills the void like a flitting firefly in the smoggy night sky, a brief flash of light— followed by an endless expanse of nothingness.
That’s okay. You’ve grown accustomed to it like a goldfish stuck in a glass bowl. You swim, back and forth, over and over and over again until you can’t anymore. It keeps you occupied, distracts you from your lonely, miserable existence.
Until you meet someone who simultaneously fills the void, and drags you so much deeper into it.
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Underfell Sans x ReaderA story about the woes of young adulthood. Includes themes of abusive relationships, inappropriate age gaps, mental illness, and substance abuse.
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The skeleton family's plan wasn't to be hunted down and murdered by two crazy neighbors they'd never met.
Luckily for them, there was a reset, so they moved back in on the day the crazy neighbors moved out.
But they hadn't expected one of the neighbors to be so attractive under the mask.
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cherish these few specks of time by Rockium
Fandoms: Undertale (Video Game), Everything Everywhere All at Once (2022)
04 Dec 2025
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"O-okay, fine! Fine! I'll tell you, just don't laugh," she surrenders, face flushing hot, "you know about alternate universes, right? I told you?"
"Of course." He leans forward.
"W-well, there's got to be some universal constants across most universes, right? So, uh, I was just wondering..." and her voice softens into a pink shade of shy, "do you think we would be friends? In every universe?"
(Or: Alphys and Mettaton, across timelines and lifetimes and universes.)
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Papyrus is lost in this strange new world. He attempts to find his way, but things come crashing down sooner than he expected.
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Continuation of "Pretty Like A Car Crash"
Crumble must prove to the facility that she can handle whatever is thrown at her, except sometimes the problems come from the skeletons that are supposed to help her.
It's up to her to prove everyone wrong.
Series
- Part 2 of Crumble and her Crumbling Life
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When you were ten years old, your parents sent you to stay with a relative of yours from Ebott. Their villa was situated up on the mountainside, and you loved to explore the forestry. One day the ground gave out and you fell Underground, and faced terrors beyond your imagination. You were missing for weeks.
After you managed to miraculously return to the surface, your parents were relieved - but deeply troubled by your 'delusional ramblings'. They were convinced you were 'crazy', and feared how that would reflect on their reputation. Your doctors advised sending you to an in-patient psychiatric facility, which is where you spent the next few years in intensive therapy and counseling.
15 years later, you're a young adult with a somewhat manageable grip on life. You keep your head down, attend the social events that are expected of you, and try to be as unnoticeable as possible. Your parents arranged a suitor for you, and you're to be wed within the next year.
That is, until, those monsters your parents and doctors tried to convince you weren't real suddenly crawled out from the Underground. And they're a lot different from what you remember.
[[Underfell!verse.]]