(This is mostly my headcanon of their young adult/high school years, so don't ask)
TW: Abuse, SH, Mental disorder
Swag and Chris are in the same high school, Swag was mostly bullied by the seniors because of his recklessness and his name before "Swag" was [REDACTED] (He also mostly commited self harm by cutting his arms). Chris is his moral compass.
Hal was physically abused by the students due to him lack of defense and a quiet nerd. His father was strict but still have some caring father energy. All what Hal wants is justice.
Ever since he got bit and he has 2 personalities, he still hasn't managed it well, so his concerned-neglectful uncle sent him to a mental hospital school where he was taught scouting and hunting. Yup, his room is a rubber room.
Karen mostly picked fights on the streets for food. WPNZ got kicked from his house by his parents for not obeying them, so he lived on the streets (he also once picked fights with Karen, but doesn't know her well)
Puzzles studied drama and theater without his father noticing while in high school. The teacher said his performance are great but his academic are slight low (around C or -C, the worse one was a -D)