He sometimes behaves like a good guy with others because he is well aware of society’s norms of behavior and acting like a jerk won’t get him any browny points and he’ll be kicked to the curb or worse. At home though there are no consequences so he acts like he wants to. Sometimes people put up with abuse because they were convinced by others or they themselves came to that conclusion that he doesn’t know better because he is sick. But then you see how he is with others and miraculously he does know better.