Undertale Fanfiction
A child falls into the Underground, a world of monsters, and must find their way back to the surface.
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What is Undertale fanfiction?
Undertale fanfiction is fan-created stories set in the Undertale universe. With over 95,000 works on Archive of Our Own, Undertale is one of the most popular fandoms in the fanfiction community.
These stories explore beloved characters like Sans, Papyrus, Frisk, Toriel, and many more. Writers create everything from short one-shots to epic novel-length adventures, exploring relationships, alternate universes, and "what if" scenarios.
Most Popular Undertale Fanfics
These are the highest-rated Undertale stories on AO3, ranked by kudos from readers.
Пёсик
by lowlawowl
No summary provided.
Welcome to the Club
by Redacted_Writer
Undyne had been getting increase of dreams, all relating to a child in a blue and purple sweater. Sometimes they would be friends, in others... well...When Sans notices, he figures it's about time to let her in on a secret that only few know about.Welcome to the Awareness Club, Fishstick!
the tale of the four elements
by victoriaexmachina
leonardo has always felt attracted by the water, red son is a fire demon so fire has always felt appealing, when asriel stepped out of the barrier carrying chara he felt the wind on his face for the first time and it was truly spectacular and julie has always found comfort whenever she was standing
Tiny Terror and Shrinky Dink
by Hollowfox
✨He skidded to an unsteady halt as he finally got a close look at the two passed out Skeletons. “What the fuck?” Blue didn’t swear often, but this? This definitely merited it.✨ Error and Ink are caught in a …little… accident and now everyone else is left to deal with the aftermath.
Battle For A Amazing Wish: REMAKE
by NeonixStarbright
THE REMAKE OF BFAAW SEASON 1 A remake which seeks to improve the screen time management, writing, and overall quality for the first season to be up with rest of the series (and some better foreshadowing.) Also, there will a BONUS episode (at the very end of the season so you’ll have to wait till the
METAMORPHOSIS
by evilm00ps (m00ps)
Ant was so extra doing things like this for him. A hand written letter for Spamton, inviting him out for a special dinner.
Rules of Surviving the Underground
by writtenfanworksofGab
Frisk, driven by their family to climb a mountain with a legend surrounding it of its hikers' disappearance with a short length of rope, finds the perfect pit to hang over. But as the rope slips, and they fall into the abyss below, they find that though it has many dangers, maybe, if they can learn
Death and Reconstruction
by Redacted_Writer
On his way to Asriel and Chara's re-birthday at a human establishment known as Freddy Fazbear's Pizzeria, Sans gets hit by a car. Next thing he knows, he's waking up in the establishment, behind the stage. To make it more confusing, a purple rabbit animatronic is in his face. Things are already look
ÆTHERVERSE - The Essence of Hatred
by MsPandora
EBOTT CITY, 191XThree years have passed since the two districts of humans and monsters reunited, leaving their differences, which once resulted in a civil war, behind in order to strive for a brighter future together.In the area of Roadin, you can find a little stationery shop called "Doodlesphere",
I should be working.
by Morkat_kitty
So, I don’t like how little stories there are of Ink having a mental breakdown. So I wrote him having a mental breakdown. — Ink is laying on the ground. How did here. Why is he here? He should get up. He should go to work. —
The Devil (Flowey) on Your Shoulder
by Kitstenk
Clover gets injured falling into the Dark Ruins and Flowey can't heal it with a save. Instead of resetting, he gets the idea to help Clover a little (a lot) more directly than usual. This changes everything and nothing at the same time.
Between the Monsters and Me: They Call Me Caro
by Feeley
Two years after the monsters reached the Surface, life is slowly returning to normal, with its routines, unexpected events, and surprises. Caro discovers that friendship, chaos, and curiosity intertwine, and that a certain ambitious skeleton can make every day... delightfully complicated.
"Entre les monstres et moi : On m’appelle Caro"
by Feeley
Deux ans après que les monstres ont rejoint la Surface, la vie reprend doucement, avec ses routines, ses imprévus et ses surprises. Caro découvre que l’amitié, le chaos et la curiosité se mêlent, et qu’un certain squelette ambitieux peut rendre chaque journée… délicieusement compliquée.
The Golden Quiche
by Sophtopus
For Monsterkind, the Surface represented freedom. For Frisk, it's a return to some uncomfortable realities. It all began with a simple wish. When that wish faded, Frisk tried to move on. Except, 'moving on' was not so simple. Emerging from the Underground had put them in a worldwide s
AI vs a 13 year old
by orphan_account
We all know what's happening with AI right now, Correct? So me & my friends were talking and we decided to do a simple test on the general Ao3 Populace. (Specifically the Undertale fans because Undertale is just awesome.) Anyway, this Fic will have 2 chapters. 1 will be written by a living, breathin
ASAP-UNHARM
by Hatchett
Boy does Taylor have one heck of a 'What I did this summer!' story from Mt. Ebott Nature Camp. But that is in the past. Now Taylor gets to introduce all her new friends to Brockton Bay. I am sure this is going to go over swimmingly. Nobody could have a bad time. Surely.
Re:Dust (Dusttale X Re:Zero) Light Novel
by LazyRandomContent
Re:Dust (Dusttale X Re:Zero), created by LazyRandomContent and rovin01, with co-writer Quin and the rest of the team, is a branching story set in the world of Re:Zero. Every route leads to unique events and multiple endings, as Dust Sans faces choices that will ultimately decide his fate.
Thicker than Thieves
by Saka_Sandora
It was just supposed to be another in and out. Steal what was worth something and skedaddle. Back to...well, they didn't exactly have a home. Not anymore. Wasn't important. Back to the issue at hand. How were they to know who owned the place? What kind of right hand of a powerful mob boss lives in t
Op school battlegrounds (ON HIATUS)
by Unrelatedperson
Humans are afraid of the unknown. The solution to this problem? Welllll uhh... it's obviously to shove the problem in area 51 one and then build a school the size of America's need for healthcare since copies of the problem JUST. WON'T. STOP. SPAWNING. So follow the story of the troublemakers of win
A note of love and hate
by TanyaLoman
Спамтон Г. Спамтон глава мафии: жестокий, хладнокровный и готовый на всё, лишь бы доказать свой статус. Однако при всём этом он остаётся обычным дядей для своей племянницы-сироты.Однажды он отправляется вместе с Ноэль в гости к её лучшим друзьям Крису. Кто бы мог подумать, что именно там он встретит
Popular Undertale Ships
Sans/Reader
Sans/Reader
The laid-back skeleton Sans paired with the reader insert, allowing fans to explore a personal relationship with the popular character.
55,000 works →
Sans/Frisk
Sans/Frisk
The skeleton Sans and the human child Frisk, typically aged up in fanfiction to explore their connection across timelines and resets.
30,000 works →
Papyrus/Reader
Papyrus/Reader
The enthusiastic skeleton Papyrus paired with reader insert, focusing on his boundless optimism and genuine kindness.
25,000 works →
Alphyne
Alphys/Undyne
The anxious scientist Alphys and the fierce warrior Undyne, whose opposites-attract dynamic is canon in the game.
20,000 works →
Soriel
Sans/Toriel
The skeleton Sans and goat monster Toriel, who bond over puns and their shared care for others, especially Frisk.
18,000 works →
Common Undertale Tropes
Popular Characters
Frequently Asked Questions
How many Undertale fanfics are on AO3?
There are over 95,000 Undertale fanfiction works on Archive of Our Own, making it one of the platform's largest fandoms.
What are the best Undertale ships?
Popular Undertale pairings include Sans/Reader, Sans/Frisk, Papyrus/Reader. Each ship has thousands of dedicated stories exploring their relationship.
How can I read Undertale fanfiction on my phone?
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