When does Doug's father start acting nicer?

The inciting incident that sparks Doug's father's change of character comes in chapter 8, after Christopher has just been arrested for burglary. Doug finds his father with Ernie Eco, as usual. After receiving the news of his son's arrest, Doug's father doesn't react as expected. He looks straight at Ernie Eco. His reaction implies that for the first time, he is seeing the effects of his dishonorable behavior. Though for most of the book so far, Doug's father has acted selfishly and cruelly, this is the first time that he has really had the chance to see how his actions have affected his sons in particular. His glance at Ernie also implies that he knows what Ernie has done. Doug's father is forced to witness the punishment for someone else's wrongdoing borne out on his own son. Later on in the same chapter, Doug sees Ernie wearing the missing Yankees jacket. His father is there and is again forced to witness the consequences of his own behavior and of Ernie's crime. The transformation that Doug's father has undergone becomes evident in the last chapter. It is clear he is hurting. It is also clear that he is trying his hardest to mend his family's emotional wounds. He is learning to love them again.