Underswap Stories

(m / n) (L / n) is a 19 year old boy and he is frisk's cousin, (m / n) always looks after frisk like his own sibling because since childhood frisk has always been treate...

edit(Now that I think about it a bunch of random crap is gonna happen) Error (the FGOD) is wounded badly in a fight between him and ink. and randomly portals to the or...

Humanity is divided over one thing---the Monsters' reappearance. Some believe that they should stay aboveground, and others think that they should be sent back to where...

(ᴠᴀʀɪᴏᴜs sᴀɴs ᴀɴᴅ ᴘᴀᴘʏʀᴜs ᴀᴜs x ʀᴇᴀᴅᴇʀ) ||ᴀɴᴅ ᴛʜᴇɴ ɪ ɢᴏ ᴀɴᴅ sᴘᴏɪʟ ɪᴛ ᴀʟʟ ʙʏ sᴀʏɪɴɢ sᴏᴍᴇᴛʜɪɴɢ sᴛᴜᴘɪᴅ ʟɪᴋᴇ "ɪ ʟᴏᴠᴇ ʏᴏᴜ."|| Life was merciful enough to grace you...

What if..someone from our world was reborn as fellswap sans? But an accident when he was young leads to becoming blind for a long time and papyrus feels guilty about not...

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Long ago, two races ruled the Earth: HUMANS and MONSTERS. One day, war broke out between the two races. After a long battle, the humans... wait no, the monsters were vic...

You were a kind human who has a brother named Frisk. You and Frisk always get along until both of you climbed up a mountain. very curious if the legend was true or not...

You kind of zoned out for a bit, trying to piece together what they said, when the door opened suddenly. You let out a small shriek as your head slipped and you hit the...

Y/n L/n. A special human with a special SOUL. Yes, her Soul Trait is something new. But other than her SOUL trait she has another secret. One day, while she was at the...

This story takes place after the player vanishes from their fight with the bad time trio aka Sans, Shift, Stretch. The three got stuck there for a very long time until a...

When made by his father, the god of death, he didn't know his purpose. All he could do was kill things on accident...he didn't mean to kill them, he just wanted a friend...

This is an Undertale book Criminals have always littered the streets causing a mess and breaking the law. But what happens when criminals Fall in Love? This includes all...

In order to be seen as not soft Nightmare buries his feelings down deeper than his soul. What will happen when those feelings start to rise to the surface. Will there be...

Tiếp tục bên nick @nhi26122004 nhé <3

(As far as I know, no one has made a story about naturetale like this so..and the only reason why I writing one like this is because of fatal error part 5? Or part 4, go...

Moved from AO3 because of reasons! "You are the only maid (or worker in general) that serves for the Skeletal Household. It's a skele-ton of work, but you manage by...

Bad Time Trio meets BNHA Disclaimer: I do not own BNHA, Or Undertale, or any of the AU or any of the pictures showed

Sans and Papyrus were your best friends until randomly they just cut off all contact with you. This went for everyone else in your life so it didn't really hurt that muc...

Yeah sorry gained an idea on if someone became swap Gaster Also they may be apathetic or just confused on their feelings and MAYBE Autistic, I may be a bit wrong on ap...