1 - 20 of 1,819 Works in Error Sans (Undertale)
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Killer has heard of a pond that turns people into mermaids at midnight during a full moon. After setting out to prove it wrong, things go awry.
Note: The first 3-4 chapters or so were written a year ago, but they have such a unique soul to them that I'm not rewriting.
Updates semi-daily until August, meaning I'm trying to write one chapter every day and may or may not succeed at this task. -
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With the magical healing powers of ketchup, Sans survives a genocide run--but the rest of his world doesn't. He sets out across the multiverse searching for a family he refuses to believe is dead, struggling to come to terms with his new life and identity and making more deadly enemies the further he goes. When a rival emerges, he's forced to choose between his past and future or risk losing both.
Complete
(Yes, this is absolute crack--but I found out there was no AU where Sans's soul is literally ketchup and decided that was a problem I had to solve. There will be family fluff, plenty of angst, a bunch of AUs, and general shenanigans. I'm treating this seriously enough that I forgot how ridiculous this was until I had to write this summary.)
Series
- Part 1 of Ketchup's Apocalypse
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Recently having moved away from home and to the big city of Ebott, you’re now pursuing your dreams of becoming one of the best Siren Specialists out there. To accomplish these ambitious dreams of yours, you’ve recently acquired a job at the Ebott Rehabilitation Facility. As the newest Siren Specialist on the job, you’ve got quite a lot to learn, but you’re sure you’ll be one of the best in no time. Especially considering you’ve got quite a lot of sirens to rehabilitate.
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- Part 1 of Tundra's Undertale Fics
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Cross develops a terminal Soul disease, but his father only cares about his own reputation as a stellar Medical Scientist and uses his son(s) as lab rat to find a cure.
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- Part 7 of Nightmare's Clan
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For a very long time, Dream had been developing bad habits that only grew worse over the years. Now, he would have to face the consequences of his poor life choices. At the same time, his friends have to deal with a looming biological threat that hangs over their heads.
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Disclaimers:
Several details in this fic are heavily inspired by 'Blue joins the bad sanses' comic, so go check that out
Canon innacuracies: Passive and Corrupted Nightmare are the same person, Ink is the creator and not the protector, Ink, Error, Nightmare, and Dream, are all gods, Blue, Killer, Horror, and Dust's specific au timelines were all destroyed, and i took liberties with how the void works. Also, no Cross sans will be mentioned, i don't know enough about underverse, and there will be some OC non-sans God/entity/things later on. The fic will be split into parts, each lasting nine chapters.
Schedule: Once a week, on Saturday, Sunday, or Monday, and i will post art or a reference sheet with every chapter. Trigger warnings will be specified in chapter notes. I've never written for undertale before, so please let me know what you guys think :3With that said, the actual plot: After an injured Error crashes into Nightmare and Co's home, a close bond starts to form between the two gods, both forced villains. In light of Ink's attempt to kill Error, Dream finally starts to lose it, and Blue gets dragged along.
Average chapter length is 500-2000
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Nightmare senses a sudden large amount of death inside a Horrortale AU variant. He goes there to investigate and finds something he never expected: a human child. An Aliza variant to be precise. He didn't think much of her at first but she was going to change the entire Gang's lives permanently.
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| - Geno and Error were just good friends, nothing more but Fate decided that maybe things can go more interesting, afterall the balance is in the line, but they seem to be perfect to use.
Or
Geno's life gets fucking ruined
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Waking up buried in snow, alone, and with no memories but basic common sense?
Check.
Seeing numbers, words, and broken code floating around every object and surface?
Also check.
Looking like a walking system crash—with one eye red, the other computer-blue, and a body flickering like corrupted a light?
Triple check.He doesn’t know who he is.
He doesn’t know what happened.
And most importantly...
He doesn’t know why everything feels like he shouldn't be alive.Everywhere he looks, the world speaks in code—and he can read it like instinct. Names, stats, system files, broken timelines. And yet, the more he tries to remember, the more he feels like a mistake.
Note from the Me:
This is my take on Fatal Error—a much more none canon, wandering version of him. He’s not fully canon-compliant inn terms of power and has a different origin and personality. It’s a reimagining: glitchy, lonely, and filled with questions, bad puns, power and some more bad puns. -
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The whiteness greeted you as you woke up again. It felt almost suffocating, especially when the only other people with you didn't exactly look or act normal. You just wanted them to emote, even a little bit.
All you wanted was to not be alone but no. You were reborn as Ink after you died in a lonely ditch. Now you have to navigate the vast Multiverse with your knoweledge of your last life. As you get friends and foes alike, you notice that not everything you know is trustworthy. Especially when you're a little lost skeleton with questionable ability to feel.
After all, anything could happen in a place this big.
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Dream and Nightmare suffer from a unknown decease, but what if there was a cure?
One would do everything to have, the other, to stop their brother.
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Stitched in Ink by LeviosaDab, MagykGremlin (LeviosaDab)
Fandoms: Undertale (Video Game)
13 Jul 2025
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...“just adding two and two—i’m a scientist, and you are dumpster diving. i think we could help each other.”
The skeleton just continued to stare, warily locked onto his lab coat instead of him as they stepped back.
...“just… give it a day or two?”You never knew what you might find in the dump. But out of everything he'd brought home for a project, Sci never expected a young homeless creature to be one of them.
Problem is, feral kids don't make for easy science experiments. Now Sci's stuck with Ink: a small, strange skeleton with a past neither of them know and a future they know even less.
It's going to be hard keeping them safe in their quest to fit their multiverse. -
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This story is written by a Goldfish who had to go through the struggle of having a lack of father figure and coping with having a step-dad!
In this story, Paperjam is neglected by his parents! Ink, not on purpose, Error, very much on purpose.
Now Error wants to make amends with Paperjam, with the encouragement of Nightmare!
Nightmare is a good step-dad, Error has a LOT of making up to do, and Paperjam is a little shit.(Yes gradient is in this too, this poor baby is always left out)
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In the beginning, there was a collective of voices. The collective needed a muse, for they could not create full universes. The only things they could make were unwhole sketches, and from one of those sketches, came their much needed muse, who was named Ink.
At first, Ink obeyed their needs. Created what they wanted him to. But when Ink wants to create on his own, the collective, "The Creators", needed another being, as their viewing of Ink's creations were deemed useless for their multiverse.
That other being is a glitch that fell into the anti-void, Error.
But, even though this issue is easy to fix, stubbornness leads to otherwise.Series
- Part 1 of FGOD AU: An Alternate Story Collections
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Scythe’s Guide To Surviving In The Multiverse by MeralAce
Fandoms: Undertale (Video Game)
12 Jul 2025
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A Sans loses his AU after some traumatic experiences caused by a murderous child.
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Dear Mr.Douchebag by J4ck0l4nern_AND_T4bby_JK
Fandoms: Mouthwashing (Video Game), Break In Series (Roblox), Regretevator (Roblox), Roblox (Video Game), Forsaken (Roblox), Skullgirls (Video Game), Deltarune (Video Game), Gravity Falls, 僕のヒーローアカデミア | Boku no Hero Academia | My Hero Academia (Anime & Manga), Alien Stage (Web Series), Undertale (Video Game), Cookie Run (Video Game), The Mandela Catalogue (Web Series), Five Nights at Freddy's, ONE - Cheesy Hfj (Web Series), The Stanley Parable, 文豪ストレイドッグス | Bungou Stray Dogs, Eddsworld - All Media Types, Dream SMP, The Amazing World of Gumball
12 Jul 2025
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Scary Larry didn't hate prison. Sure, the bland concrete walls may or may not remind him a bit of the cell Mary had been keeping him in just days before he came here, but all in all, this wasn't the worst experience in his life.
Besides the place wasn't that bad, the decor, or lack thereof, aside, it was quite nice.
His cellmates weren't the worst either he supposed. Both Pest and the Player were okay at the least.
He was almost glad they hadn't gotten a fourth cellmate yet. It had surprised him at first, that each cell had exactly four people in it except theirs, it made sense in hindsight, the fourth bed in their cell sort of gave its purpose away just by existing, but so far the prison hadn't had a need to give them a fourth cellmate, fourth bed be damned.
Or at least those WERE his opinions. But NOW, Jimmy Mouthwashing is here. And just GUESS which cell he's been put in.
Series
- Part 2 of Dhar man plauge
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Hello, my name is Mazy, now that you will be a reader soon, you are known as a Mazyville, I'm nonbinary and go by they/them. My favorite fandom is Undertale and its alternative universes. I write semi-literate so all can understand well. English isn't my first language, though, so don't be too bitter.
I'm not a new writer, but I've never written on AO3 before. I'll be taking requests for any fanfiction Idea you have, not a short, but I'll make a not-so-long story about it. Just comment with your main idea or a summary of what you want your story to be, it can be ANYthing and ANY ship.
READ THE REST OF IT TO FIND OUT MORE!! AND READ THE NOTES!!!
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After drowning as a human, Ashe reawakens as a DustTale variant of Sans. With his ghost Papy helping keep him from falling into suicide a second time, Ashe slowly learns he can have fun, and what's more fun than fucking with the Star Sanses who have totally mistaken him for the 'evil' Dust Sans?
Edit: Story is still ongoing!!!
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Nightmare was a curious spirit. He always asked questions, annoying the living daylights out of anybody who cared to listen. However, despite this being an annoyance, it was one of the main reasons Nightmare survived long enough to witness his failure as a Guardian of Negativity have its toll on the Multiverse.
He is failing. The balance is so out of whack that positivity is corrupt unless balanced out with negativity, turning toxic due to its stagnation in the Multiverse. Negativity is positivity's purifier, after all, and without it the positivity goes bad.
And Dream certainly isn't much help, what with him hell-bent on destroying any possibility of negativity naturally occurring.
Nightmare is losing hope, angry at himself for his inaction.
However, he forgets one thing: this is the Multiverse. And anything is possible.
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- Part 1 of dreamtemple
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While the characters believe the multiverse has existed for thousands of years already, it truly starts with the first sentence of its story. Only Ink feels when it happens.
(...And then panics because he's now aware he's never actually protected a universe or had a conversation with a friend and probably doesn't know how to do any of that and they're all counting on him.)