I don't think it's fair to blame the brother. He's a 17 year old boy, and they're totally self-absorbed.
He didn't create this mess, he's dodging that jackass Onstott TOO, he's had to grow himself up by himself too. He was there alone in the trailer by design - no one misunderstood where he was - he was left alone.
He didn't cause this. He's a victim too. That there was no food in the house at midnight (maybe there actually was a lot of food, we don't know, maybe she wanted something different) wasn't his fault.