What does it mean when a guy does this?

So there's this guy and we hangout alot. Now all of a sudden he's startin to try to hangout with my brother. And he was never rly nice to him before. Is he doing this cuz he likes me and like wants to make me happy or what? Is he gonna try to become friends with him and ask him about me? Guys, if this sounds familiar, what does it mean when you guys do that?