Amir and Baba's relationship is not a normal son and father relationship, which is that the father will/should support their son's decisions in who they want to be. But Baba does not because Amir is not like him because Amir reads and writes and doesn't stand up for him self. Bada is a powerful man and stands up for him self. Amir is jealous of Hassan and the orphan children because Baba shows more affection to them then Amir. Amir always feels like he is disappointing Baba. But Baba is there for him when it counts like when the shooting happened and when they talk in Baba's study.
In Hassan and Ali relationship, so far Ali seems more like a father then Baba because he conforms the boys when the shooting happens and he also chastise Hassan when he does something wrong. Hassan and Amir seem more closer together because they live in a small little shed. Unlike Amir and Baba who have a bigger house and have more freedom to be on there own.