1 - 20 of 4,380 Works in Alternate Universe - Underfell (Undertale)
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A fanfic set in Underfell focusing on Flowey and the events that occur.
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Roman thinks it's funny when Red cries.
Mostly.
(Akin to a 5+1 but the author didn't keep count and also just did what she wanted.)
AKA: Roman flirts, then fucks, then has a baby with, Underfell Sans
Series
- Part 13 of Dead Dove Antics
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Dimensions and Magic by Vimub
Fandoms: Undertale (Video Game), Harry Potter - J. K. Rowling
25 Nov 2025
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Harry Potter is sent to another dimension to pave the way for magic to escape total annihilation, except he ends up stranded alone.
In this seemingly normal world, the day monsters emerge is a shock — but not as much as when, months later, some artifacts start to detect the arrival of fellow dimension travelers… from a dimension that isn’t his.
Series
- Part 2 of Harry Potter and The Monsters
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"I'm sure you're wondering what's going on here."
"Not really."
"You are genuinely one of the most pedantic people I have ever met in my existence."
"Well, I don't know what that word means, so therefore I can't be it.".
.Ah, frick, just my luck. Reincarnation as a skeleton with godlike magic capabilities.
This should be fun.
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Two friends, split across the Multiverse.
Two friends, with opposite ROLEs of the Protector and Destroyer.
Both just want to find their friend, for them to be ok.
The Multiverse has bigger plans for them, however...
One friend fights valiantly for what is right.
The other falls into the darkness.
Or: two kids make themselves spawn in the UTMV as Ink and Error, and both are overpowered.
Generally random updates but I try to keep it consistent to once a week.
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Good Intentions (Frans Edition) by Dale (Dale_the_Human)
Fandoms: Undertale (Video Game)
25 Nov 2025
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Frisk comes across a slave owner beating up a skeleton monster with a gold tooth. (Based on the premise of "Slavetale" by V_mum)
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If Angels Have Halos Do Skeletons Do To? by Tiddlywinks9
Fandoms: Undertale (Video Game)
24 Nov 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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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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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.]]
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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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Unavoidable Outcomes by Crystalight532
Fandoms: Undertale (Video Game), Undertale Yellow (Master Sword Video Game)
22 Nov 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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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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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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Escape isnt always easy and freedom isnt what its cracked up to be.
Series
- Part 2 of Ebbot Mountain Zoo Chronicals
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Look what happened to my good intentions by Dale (Dale_the_Human)
Fandoms: Undertale (Video Game)
21 Nov 2025
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You are a monster-sympathizer who has just rescued a skeleton monster (UF Sans) from his abusive owner. Unfortunately for the both of you, the man left before transferring ownership and the skeleton is frozen in place from the last command.
(Based on the premise of "Slavetale" by V_mum) -
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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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What if you're finally free? On the surface with all your dear friends? But then an incident...
What if a reset happens?
I'm back with another what if for my first fic (a new life with a bunch of monsters (and annoying humans))
God i need to stop😭Series
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It takes 10 Skeletons, not a village by Donewith_life
Fandoms: Undertale (Video Game), Underfell (alternate universe), Underswap (Alternate Universe), Swapfell purple (Alternate Universe), Horrortale (Alternate Universe)
20 Nov 2025
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You mum drags you to her boring science lab, forcing you to help her with her research, against your will and interest, until late at night. You're in a lab late at night, what could go wrong?
(Reader is 15 so NOT a romance between reader and the skelebois.)
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"I'd Rather Do Normal "People" Things...Thanks!" by Cr8ter_Eight
Fandoms: Undertale (Video Game)
19 Nov 2025
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You are a Normal Person in pretty boring world.
You wake up.
Brush your teeth.
Comb your hair.
The same repetitive, insigniFi6@^t- th!^g every $ingle day....
One day, you do the same thing.
On that same day, you don't notice that an Insanely huge skeleton has tumbled out of your closet.Amazing.
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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