While I understand where you come from and I mostly agree with you but I won't 100% blame the brother either I mean his family tried to steal his inheritance etc plus he has a mental illness so while I agree that he should not have hit his sister I don't fully blame him alone for it
But a mental illness doesn't make you an assholeand shouldn't be an excuse for shitty behaviour. He definitly got some issues he needs to work on, some that he can't help, I get that. But his abuse is defenitly not caused by his depression or can be excused by it. So yeah I think he is 100% to blame.
That's where I disagree, yes he's got issues and I think his abuse is a part of that, I mean you saw it in the rental onii san guy he was an asshole as a kid because of what happened to his parents. I mean of course it's still his problem and he should, I don't remember the right word sorry, and visit a psychyotrist and get proper help and actually look through his actions and apologize etc, I mean it's not only depression but also probably trauma of all his family members trying to get his money instead of actually helping him and his family which probably made him on edge all the time and probably also lost most of the trust he had in others, of course it doesn't completely make him free of blame, If I was there I whould probably punch him and drag him to a psychyatrist for help, but I also think his family has a cause in him to end up like that so I whould definitely blame them a bunch too
By family i dont mean his sister but his uncles etc
Even if the brother gets help later on, I think it'll be a lot healthier if the girl stops living with him and he just visits her if he wants to. I don't care if he's depressed about everything happening, taking it out on an innocent child is unforgivable, but this is fiction and there's the tragedy tag, so who knows what will happen...