I find it interesting she paints her brother as a kind of sympathetic character, and I sincerely am starting to think he's suffering from PTSD.
I'm starting to think what happened was that his father sexually abused him when he was younger and so he's molesting her because he wants to take control over his sexuality, but doesn't want to actually cross the line into penetration. Hence why he's very uncomfortable around his father, why he's screaming and crying all day when locked in a dark room, etc. He's not doing it out of a sense of lust but out of a want for control in his life, which is common among predators.
Granted, he's still a piece of shit, but it's more due to psychological issues and I think he's meant to be a tragic character.
@hinabestwaifu Seriously?! Imagine going to a rape victim and saying she's used goods. Like goddamn, stop thinking with your dick, man.
@Tearsax Bipolar behavior aside, mental instability comes with mood swings and when you're in the thralls of depression, you might do some fucked up shit to try and get some sense of control.
@pihip Pretty much my thoughts