I'm thinking that my brother might be on the spectrum aswell. I haven't told anyone that I think of this but some of his traits fit (and it runs in family, me and my cousin have it, my dad seems like he could have it too).
My brother is 20. He has one good friend that he has known since he was six, and a few other pals who he knows only through this 'best' friend, who also happens to be very extroverted, dragging my introvert brother into parties and such sometimes. He has online friends through gaming, from all over the world. The way my brother lives currently is this (and has been for many years): he plays computer games in a dark room, curtains closed and it's a mess in there, he can't keep places organized. He talks quite little, but I seem to be on the same wavelenght with him, we have similar humor, we say stupid and made-up words and sentences in silly tones of voices to each other, thing I can't do with my sister for example. He has been aggressive at times, especially regarding playing too much computer or playstation games, his school went badly in high school but he has done fine after that. He hasn't had a proper job in his life though.
I might delete this later, I just had to write my thoughts somewhere...