Baba has a secret which is not revealed until much later in the novel, but it is obvious that Baba treats both Ali and Hassan as more than just servants. Ali has been with Baba since they were children, and they were playmates much in the same way as Hassan and Amir. Baba treats Hassan almost as his own child, and we discover later that Hassan actually is Baba's son by Ali's wife. It explains why Baba admired Hassan and gave him such nice gifts, presenting him with the operation to rid him of his hairlip. When Amir suggests that Ali and Hassan need to be replaced, Baba explodes, telling his son that they are members of the family. Things change between Hassan and Baba only after Hassan is falsely accused of the theft of Amir's birthday gifts. Hassan refuses to defend himself, admitting that he was the thief (and probably understanding that it was Amir who had planted them). Whether Baba knew this is unknown, but he was unable to keep Ali from leaving the household, and Baba never saw his son, Hassan, again.