hhmm you might have a chane. just watch how he acts around you. he could be :
a) staring at you
b) when you're talking to him, he actually pays attention to you
y'know .. signs like that. i don't think cliques really have anything to do with. i have a crush on a guy who i've liked for ages, and i'm sure he likes me to. the problem is that he has a girlfriend at the moment. so i keep my trap shut.
get to know him better, he's not going to go out with you if you just ask him out and he barely knows that you have a brother that's five years older.