Sure you can poison him... but I'm 99% sure he's the best you can do. And NO, you're brother/uncle/father/step-father don't count. Plus, he's probably the only person who cares about you, even if it's just to beat your ass black and blue. So yeah, that's better than nothing since he's probably the bread winner between you two... which is not bad for a physically disabled and mentally challenged mule... he's done well for himself.