I am actually really struggling with this right now... to the point where I am searching for a therapist to talk about it. I've always had anger issues, so I don't know if T is actually what's responsible here, but I have noticed lately that it's much easier to trigger that aggression.
I mean, I guess it could just be puberty. Everyone handles it differently. Some things crop up for certain people that never do for others. This could be one of those things.
Do you know what his parents are like? In my case the apple doesn't fall too far from the tree. My behavior is mirroring my dad's quite a bit, and I have no doubt I am genetically more predisposed to this kind of anger. The sooner I can talk to someone about it, the better my chances are of not becoming him.
I will say that since starting T I've felt more comfortable just being myself. The things I do and say aren't any different from the things I would have done pre-T--it's just that I'm more comfortable in my skin, I'm starting to own my body, starting to feel like a person, you know? Like I finally have a place here, socially, physically, everything. So maybe to an outsider I act a little differently, but truthfully the only thing that's changed is that I am simply participating more.