A nonbinary prick and one of Jesse's characters, Jess was some human teenager who thought it'd be a good idea to sneak into the pizzeria, and then they were killed and became the pissbitch corgi seen to the right of this page.
Jesse's Withered Golden Freddy is most likely, despite how much it is hated by them, the one closest to Jess these days, considering their brother was retconned and may not even exist at all anymore, human or 'tronic. They haven't really met his other characters, or Jesse himself.
Jess sometimes ends up fused with WGF in the form of Jey.
Jess also seems to have some kind of almost mental disorder-like thing going on in that almost none of their sentences they utter DON'T contain foul language.