Umm, he likes you.

I don't think most guys put in time to be "just friends". Its like on That '70s show when that dude is going after donna, and hes like "I listened to you, I spent time with you, shared ideas, whats that all about?" and shes like "I thought we were friends!" so yeah...guys don't play games, if they like a girl they put in time and hang out with her like your lil bros friend is doing with you.