The girl who bites herself to spit blood in the eyes of people she wants to run from is beginning to suspect something's wrong with herself.
I find her quite sweet and vulnerable. It's sad that her brother is only concerned about himself.
He's genuinely upset about Paul's death and Maria's slip actually hurts him, but he only knows lowlife ways to express it... well, he'd know other ways, but they'd involve more self-awareness than he could tolerate. They both did evil things early into the story, but only her is beginning to accept that their life isn't normal.
Yeah, her brother is some piece of work.
He has a big pile of issues to dig through before you can even get to his bad temper!