Susie is initially introduced as a bully in Kris's class, threatening them in the opening scenes before they ever make it to the Dark World. However, she'll experience a significant character arc...
Susie is one of the main protagonists of Deltarune. She is an aggressive, socially withdrawn monster and a classmate of Kris. She joins Kris on what was supposed to be a quick trip to the supply closet to fetch chalk, but instead fell through a portal into the Dark World.