Well first of all thanks for taking my request, well that is if you actually make this based on my request but who cares
anyway since they're related they can be friends or even bff, i can see Conrad probably talking to him a lot or probably he's the person Conrad would go to talk about his problems. Considering how Conrad doesn't have too many friends due to his rather blunt personality, they can probably be quite the bff.
on a slight more serious and err crazy note, i have this very very very very very very crazy idea, i don't know if you'll like it or not but i'll just write it. Maybe Ren can have a crush on Conrad but just a crush, but he doesn't want Conrad to know and that's why he's Conrad's bff. I'll just put that in there right now before moving on and probably i can think of more ideas later on.