The Universe (Undertale AU's)

(Twilight (Twi) X Undertale Gaster ) (Layla (Lila) X Underfell Papyrus ) ( Scarlet X Undertale Papyrus ) (Niquel (Lily) X Undertale Sans ) ( Underswap Papyrus X Underfell Sans ) ( Underswap Sans X Undertale Frisk(girl) ) ( Underswap Chara(girl) X Undertale Chara (or Char) (boy) ) ( Undertale Asgore X Undertale Toriel...

A Little Insane: The Dark Prince

[Book Three] Hart enters hell to search for Riley, instead finds that 30 years have passed when only three months have gone by on Earth. Not only does he find Riley, but he also finds the true purpose of his existence and it doesn't give him a pleasant vision of the future.