Undertale Fanfiction
A child falls into the Underground, a world of monsters, and must find their way back to the surface.
Start Reading Undertale Fanfiction
Explore 95,000 Undertale stories on Archive of Our Own, sorted by popularity. Then enjoy the best reading experience with Fanfict Reader.
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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.
Undertale Fanfics by Length
Pick a reading commitment — from one-sitting one-shots to 100k+ epics:
Best Undertale Fanfic Rec Lists
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 →
Papyton
Mettaton/Papyrus
Papyrus is Mettaton's most devoted fan, and the robot celebrity's date with the skeleton is one of Undertale's beloved optional gags. The pairing matches two of the Underground's biggest hams: a glamorous performer who craves adoration and a skeleton whose adoration is utterly sincere. Fandom treats them as the monster world's most theatrical power couple.
2,500 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?
Download Fanfict Reader for iOS to browse and read Undertale fanfiction with a beautiful mobile interface, offline reading, and custom themes.
Read Undertale on the go
Fanfict Reader is the best way to browse, search, and read AO3 fanfiction on your iPhone. Download for free and start reading your favorite Undertale fics today.