Just gonna say, I've seen people ship these three as a poly relationship, but I view them more with a friend/sibling relationship. Sorry :(
Caleb
-Does wear clothes sometimes, mainly when around the other characters, but prefers to not wear them like in the PV
-Voice of reason in the group
-Intersex, prefers he/they pronouns
-Polysexual
-Generally very quiet, which is odd considering his song is the only one with lyrics
-The two mannequin dudes from the PV follow them around, they don't speak and are generally very chill
Adam
-Logical thinker, but struggles with confrontation
-Gay cis man (he/him)
-Gets along with Norman, mainly due to them both being religious (Adam wears a bishop's collar in the image)
-Goes along with Diane's shenanigans
-Gets creeped our slightly by Caleb's mannequins, but hides it so Caleb doesn't get upset
Diane
-Chaotic one of the group, gets into trouble a lot
-Pansexual demigirl (she/it)
-Likes to mess around with Caleb
-Sometimes hangs out with the other trio (Candle Queen, Rag Doll and Aura)
-Has tried to start fights with the other characters, but gets stopped by Caleb