Destruction of DETERMINATION (Sequel to SAVE Your Timeline)

(Set a few MONTHS after SAVE Your Timeline)
(This book is from Frisk's POV)
(Book 3 [Final book of the series] will be from Chara/Error's POV)
Error, after finally giving Frisk's Determination back, left the timeline alone. Sans had to say his goodbyes to this Sans, Frisk, and Flowey. Then he left. Never to be seen in that timeline again. Gaster took him back to his original timeline, and prevented the occurrence from before (the beginning of SAVE Your Timeline) from happening. Two timelines were safe, out of harms way. But a new threat posed to destroy the monsters and humans. They fought Sans before. They even killed him once. Another anomaly.

Chara.