Adult vs. Child Amir

After I read the six chapters.I believe that the adult Amir is different to the child Amir.
Although Amir can not faced to the past in the beginning, but it is just the beginning.When Rahim Khan talks about Hassan's son. He want Amir to take the child to Thomas's charity organization. "Rahim Khan, I don't want to go to Kabul. I can't" I said.(Page 220 Chapter 17) Amir can't face to the past. After that, Rahim Khan said the words what Baba said before. "Rahim, a boy who won't stand up for himself becomes a man who can't stand up to anything.", then Rahim asked, " I wonder, is that what you've become".(Page 221 Chapter17) And Rahim add the most serious words which is "What I'm asking from you is to grant an old man his dying wish." to made Amir can't say no. "Maybe Baba was right"(Page 221 Chapter17) Amir replied. All these seems that Amir is just like what he was in his childhood.He still can't give a hand to Hassan to get away from the trouble. But later. When he was in a smoky little samovar house. He woke up, he got the meaning of Rahim's word."There is a way to be good again"(Page 226 Chapter18) He knows that"Rahim Khan had summoned me here to atone not just for my sins but for Baba's too"(Page 226 Chapter 18). And then he made the decision, he decide to go to Kabul to take Hassan's child. Now he is not the boy who won't stand up for himself, but a man who is not only stand up for himself, but also can stand up for others.
Remember that when Amir was a child. The child from the rich family laughed at him to play with Hassan, they said that Hassan and Amir are good friends. But Amir deny with that. But when the night he was talking with Wahid in Wahid's home. Wahid asked about the relationship with Hassan and Amir. Amir avowed that Amie is his half-brother."He was my half-brother"(237 Chapter19)Although Author just described how it related to Amir's father. But it can reflect that Amir is not the child Amir. He have the norve to avowed that Hassan is his brother. We can image that if it was the child Amir talked with Wahid, the answner to Wahid's word"He was a friend of yours?"(Page 237 Chapter19) must be some words like, "yes, a friend.".