Rage. That is the first thing I've felt from the moment of birth and I've suffered way longer than that as well. more will be explained in the book.

You are Y/N W.D the son of Gaster and a Human woman that died a few years after Gaster's disappearance. You are a half skelleton Monster with the trait of BRAVERY. You are brothers with Sans and Papyrus you take after Sans in enjoying puns and you work a part time shift at Grillbys and in your spare time you train your physical strength as well as read about things like Monster and Human history or the Human souls. You partially remember the timelines not as much as Sans does though only remembering most of the pacifist run exept for Omega Flowey and Asriel and only Sans Papyrus and Undyne's death it always confused you on how you don't remember your own death.