Mostly saying very silly, juvenile, unnecessary things in an argument and having grown up since then, I feel a lot of shame. That I didn't need to say anything at all as now I see the tediousness in cheap arguments -- unfortunately, back then in my early teenage years, I couldn't see how useless conflict was. I've forgiven myself for this, however.

Regarding my brother, I'm not sure what happened there... My brother has autism among other things and so he takes certain incidents very seriously whereas it wouldn't matter as much to anyone else. For instance, I moved one of his belongings not knowing the magnitude of its significance to him so he lashed out at me. But I didn't understand why he was so angry over something so silly. This exchange would repeat itself until mid-way through my teens when we'd find out there was something more going on mentally.

I forgive myself because as a child and throughout my early teens, I didn't understand mental health so I couldn't take the drama seriously and so handled confrontation/teasing how I would with anyone else. I don't blame myself too much. It's unpleasant, knowing things could have been a little better, had I known what was going on and now being powerless to change the past.