By the time Stray Kids project starts, Hyunjin & Changbin have worked some things out. They're already pretty handsy with each other and it escalates now that they're supposed to perform skinship too.
Hyunjin eats up all the skinship, can never get enough of it, and still wants more.
Changbin has figured out the "more" that Hyunjin wants, but he's waiting for Hyunjin to figure it out for himself.
Because Changbin is scarily mature & self-aware for a teenage boy, what the fuck, he's a freak.