repositorian: he is a biter. He loves marking his partner up to show ownership and loves it when his partner does anything to claim that hes their's in return.
Rocksintreetops: oh that's a tough one. it's never stated in game what he loves most about mc cause its supposed to be YOU and everyone is different HOWEVER I headcanon that since his whole thing is he has to gaze into another's eyes to use his aethercore he has a thing for pretty eyes. Also hands.
he will always find a reason to hold hands with someone he's really into OR just be touching someone he really loves and has his big hands on them. sylus canonically has really big hands
honestly I forget how much bigger than the other guys he is as a whole until I see him against the other men. sylus is top left. hes also currently still the tallest male in the game (we will see what happens when the new guy comes in)
he doesnt really like other birds in canon. he's had to take care of some other birds like a dove and most recently some exotic one i never heard of but he doesn't like them. he only likes crows. (much like ACTUAL crows)