When a silly prank takes a nasty turn, Nico finds himself falling into the underground. Trapped behind the magic barrier, and exhausted from the previous week's trip, Nico finds himself walking his way through the underground. Set right after the war with Gaea, Nico replaces Frisk on a true pacifist run. Lots of fluffy shenanigans.
Crossover - Percy Jackson and the Olympians & Undertale - Rated: K - English - Humor/Friendship - Chapters: 6 - Words: 26,439 - Reviews: 96 - Favs: 169 - Follows: 231 - Updated: 6/6/2016 - Published: 1/19/2016