1 - 20 of 3,108 Works in Alternate Universe - Underswap (Undertale)
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You were a normal human. You went to college, you had a life, friends, family, etc. Apparently, the void didn’t care much for happy endings, and you find yourself strapped to a table in an underground lab.
It’s fine, you have plot armor.
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Or, you get sucked into the void and your soul is placed in the body of eight-year-old Sans.
Arc 1: Heritage (1-7)
Arc 2: Hell (8-10)
Arc 3: Home (11-45)
Arc 4: Heart (46-59)
Arc 5: Hostage (60-?)Series
- Part 1 of How To Be A Human Being
- Part 1 of Hounds Of Love
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You are on death's bed, there is no denying it at this point. Your good friend listened to you rave about an upcoming otome game you have been desperate to play since you've heard of it's creation. Only to sadden when your prognosis would keep you from seeing it in your lifetime. Well this good friend manages to get you a copy. So who would have thought that when you eventually passed on, you'd wake up as a healthy you? With goat ears, nubby horns, and a cute fluffy tail? Also a barrage of skeletons waiting on you hand and foot, calling you their queen... After playing many routes, there is one thing you are sure of... To make sure Black doesn't kill you like he does in the game... yet you don't seem to understand the stark contrast of yourself vs the queen as the skeletons do... and if you aren't careful? Black and the others will fall head over heels for you.
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After playing undertale late at night and being sucked through your computer to that universe, you and your bone brigade have to figure out what it's like to live in a new world. And maybe try to get you home. If there's time.
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After falling into the Underground, you find that you don't have what it takes to break the barrier. You and everyone else are thoroughly disappointed. Things are rough at first, but you slowly adjust and accept that your new life will be among Monster-folk. You work through your trials and tribulations in the Underground, make new friends, even land yourself a job, and... fall in love with a certain skeleton? How charming.
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Sorry for the really vague description, this is my first fanfic 3
So.. I hope it's bearable and that maybe someone will enjoy it ! -
random stories i feel like writing by Astral_johnson
Fandoms: Voltron: Legendary Defender, The Amazing Digital Circus (Web Series), Cookie Run (Video Game), Xiaolin Showdown (Cartoon), Naruto (Anime & Manga), 鬼滅の刃 | Demon Slayer: Kimetsu no Yaiba (Anime), Harry Potter - J. K. Rowling, Pocket Monsters | Pokemon - All Media Types, Homestuck, Undertale (Video Game), Wild Kratts
06 Sep 2025
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this doesn't take place in anything just something i randomly made up
asher(i like this name) is the mc
asher was running from demons he's a incubus who finds a church -
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*Updated*
After Monsters started living with humans, colors symbolized different things to you. Blue was your favorite color, but now it reminded you of your ex and stood for stop. At an unstable point in your life, you encounter a skeleton who looks similar to your ex. His eyes were like stars. He calls himself Blue. This fated meeting was the beginning of a chaotic spiral. Danger and drama seem to follow these skeletons. And why are you meeting more of them?!!!You may have lost your first love. Hopefully, with all these skeletons. You might learn to love again and overcome your dark past. After you help them with their heat...once you LEARN what that is. Good luck your gonna need all your PATIENCE to deal with them.
Love and misunderstandings begin! #this will crash and burn #Enjoy the dumpster-fire
A Harem of Skeletons!...too bad its a slow burn. -
System Error: Accidental Acquisition of Children by Frikisbits231
Fandoms: Undertale (Video Game)
05 Sep 2025
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Summary
Error slid down, glued to the tree, his back to the ground, into the lush green grass on the ground. Later, he'd take a look at his current situation and possibly eliminate the place without a problem. Meanwhile, Error was resting, leaning against this comfortable, curvy tree, closing his eyes to feel something, something of the place.
Feel... the familiar ambient magic?
Still no monsters, humans, or standard souls around. Well, no one could hurt him if he got some rest, right?
This time, he mentally prepared himself and repeated the safety tests he felt like a mantra so he could get some rest.
He fell asleep shortly after.
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Sweetness with hints of security, calm, and the tranquility of dawning rest captured his senses. Something... familiar. Like... like chocolate melting on his tongue. He didn't know how he recognized that either. Still, he pulled the tongue out of his space, to capture it. He caught the sensations, almost becoming overwhelmed by them.
(O: The one where Error acquires an abandoned baby bone, which is, of course, his offspring too, yay...)
Series
- Part 3 of Glitches & Errors Fics
- Part 2 of Random Writing
- Part 1 of ❤️🩹💞 Caring for Babybones 💞🥰
- Part 1 of Oh, look at a fanfic with one of the fanchilds!
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An ill-thought through party in the woods leads to you getting lost with a dead phone and no way to know where you're going. When all seems lost you stumble across a cabin hidden in the dark depths of the surrounding trees. In classic horror movie hero fashion you find yourself entering the creepy house to find more than you bargained for; including quite a few skeletons unearthed from the closet.
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You'd been happy. Life had been going perfect. Until it wasn't. You lost those dearest to you and in your mourning and grief, you suddenly find yourself staring at the machine in the basement. Then you're whisked away to another world and things just seem like so much given all you've already gone through.
How will the Skeleton House react when they learn a secret even you don't realize you're hiding? And can they help you recover from your grief?
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Same You, Different Font by radskull69
Fandoms: Undertale (Video Game), Deltarune (Video Game)
02 Sep 2025
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Ah yes. The classic ‘’Heather’ convinces the skeletons you’re an evil human so now it’s a EVIL reverse harem’. Right?
Oh? But what’s this? A TWIST?
Sans couldn’t live with himself after what happened to you, going near insane after you’re gone. So behind the others back he uses the machine to undo what he did, except it didn’t. He can still feel his sins crawling on his back.
Oh well, it’ll all be worth it once he has you back in his cold hands again. Screw the other skeletons.
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Después de que la Antigua máquina de Gaster se rompiera y trajera otras versiones alternas de sans y papyrus, sans tiene que lidiar con otras versiones se si mismo y de su hermano qué lo odian con el alma. Pero lo que no saben es que descubrirán secretos que nunca hubieran imaginado.
Esta historia esta inspirada en "10 Skeletons With 1000 Years to Go" esta es una historia muy buena y la recomiendo completamente, me inspire mucho de está historia
- Language:
- Español
- Words:
- 1,069
- Chapters:
- 1/?
- Kudos:
- 1
- Hits:
- 16
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You're an engineer who works for Ebott's best research facility in one of the labs; your lifelong dream after finding a journal on Mount Ebott when you were a kid. When you aren't in the lab being smart, you're gathering materials at the abandoned doll factory for the machine you're trying to build.
But one night, you meet a skeleton at the factory. Naturally, you lie about why you're there and say you're there to hunt ghosts. You befriend him and try to find a way to gather the materials while keeping up with that lie. But those lies catch up to you when you start to meet all the other skeletons.
Edit: As of Chapter 29, all chapters have been edited and fixed slightly!
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It was like you were never there at all.
Series
- Part 11 of Under the Tale (Just Air, Got You)
- Language:
- English
- Words:
- 266
- Chapters:
- 1/1
- Kudos:
- 2
- Hits:
- 24
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Just an ordinary Halloween night.
It was meant to be that way.- Language:
- English
- Words:
- 2,440
- Chapters:
- 1/1
- Hits:
- 0
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Making A Monster by absurdmagewrites
Fandoms: Undertale (Video Game), Underfell-fandom, Underswap-Fandom, Swapfell-Fandom, Fellswap-Fandom, Fellswap Gold-Fandom, Horrortale-fandom, Crafttale-Fandom, Seaswap-Fandom
31 Aug 2025
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Sometimes life throws you a curveball. For you, your curveball was going to bed looking like a human, and waking up looking like a monster.
A skeleton monster to be precise.
With the barrier breaking, a large surge of magic descended on the town you live in, and transformed you overnight. Unsure what to do with you, and the others changed, you're ushered into a facility until a monster with similar magic can take you to teach you how to wield the now uncontrollable magic you've been given. After waiting in this place for four years, you'd given up hope that anyone would ever want to take you.
What a surprise for you when you find out that someone does. A lot of someones.
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The House Next Door by BattleMaiden13
Fandoms: Undertale (Video Game), Underfell - Fandom, Underswap - Fandom, Swapfell - Fandom, Mafiatale - Fandom, Mafiafell - Fandom, Mafiaswap - Fandom
31 Aug 2025
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The first time you met monsters you manage to run into four of them and literally run into one of those four. Now they are apparently moving in next door with their siblings and you can't seem to imagine a life without monsters. On the plus side they tell horrible jokes and have endless amounts of energy. So what could possibly go wrong.
Part 1) Chapters 1-138
Part 2) Chapters 139 - ??? -
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What happens when everything changes? Everything is the same but it isn't.
An entity from the stars descends to earth and disguised themselves as human. They witness history in this new era of monsters and humans, while also dealing with the demons that dare dirty the earth with their presence.
What happens when you step into the battleground from one universe, only to win and come out into another parallel world, except you’re the protagonist?
You weren’t one for the spotlight. You loved your sister, even if she wasn’t one by blood. You only wished for her well-being and happiness. Except here… she’s gone. And now you have to take her place and stand under the limelight as you walked your path in her place - the protagonist.
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I DON’T CONDONE MY WORKS TO BE TRANSLATED, REPOSTED AND/OR FED TO AI.
9/1/25 — thank you for 600+ hits!
Series
- Part 2 of Still As Stone AU
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Monsters were set free! But it costs the humans their freedom! Humans were mass murdered by Underfell and Swapfell, set free from their universe by monsters who were trying to do research on time and space, only a certain percentage of humans remain. Most are enslaved and the ones that are not are lowest of the low and can barely come by.
Y/N is an orphan. She was kicked out of the home, she was too old to stay and thus had to live on her own, no money, no food, no shelter.
You! Reader, is going to choose how she either lives…or dies…
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A mutation has spread across the globe when monsters were released, humans either dying as their bodies couldn’t handle it or mutated with the rest.
The mutation was simple really, a change of dynamics. Humans started taking more unusual forms, growing more than a few ears, eyes, arms, legs, shit even a head at one point. Or body morphing differently altogether. Turning into their worst nightmares.
Y/N being a young child at the time of the outbreak changed with the rest of her family, half of her family died or killed themselves resulting in her being an Orphan at a young age, left alone in the world as her body shifted and changed. Body becomes leaner, smaller…cute. Cat-like ears and tail sprouting from her body, legs breaking and reforming into back hind legs of a cat's, fur covering her legs stopping at her waist.
Not only that, but she is an Omega.
Of course she doesn’t know oh no no no blissfully unaware, well that is until an over caring human Frisk decides to visit the Orphanage dragging along her friend Chara. Whom in turn absolutely dreads the visit. Let's say…frisk was the door to meeting a rowdy group of skeletons…
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Life is perfect. Everything you love is safe and secure. That is until you and your family is suddenly hunted down by a mysterious gang out to get you for reasons you can't explain.
Another thing you can't explain? Your dreams. At least, you think they are, but being fallen down certainly doesn't help. Ancient languages and nightmares fight to become your greatest fears. Can't get worse than that, right?
Fortunately, you'll have some help along the way from a pair of skeletons. Even if life isn't what it used to be.