Sans has to do the unthinkable. The human is dead, and so is every other monster in the underground, all that are left, are Papyrus, Sans, Asgore, and Flowey. Papyrus started to remember the time lines, and he began to think "What matters anymore" He gave up. With the words of Flowey in his head, and the anger in his heart that he can not fix anything, he goes with the solution that Flowey gave him. Gain Love, gain EXP, gain DETERMINATION, by termination. To finally set everything back to normal.
The barrier is broken, monsters and humans are living in peace, everyone is happy except for one person. Frisk has been getting waking nightmares about not saving Asriel. They want to save him to erase all guilt and to be with their friend. But Asriel isn't the only one that needs to be saved. Something, someone lurks inside Frisk's soul. Someone deadly and has a hunger for power, and can kill anyone they want.
A/N Frisk and Chara are both gender ambiguous in this story. Also there will be a little bit of Frisk x Asriel in this story, but this is not a Frisk x Asriel fanfiction. Credit to @karinacat59 for the cover. Undertale belongs to Toby Fox and none of the characters are mine.