I believe that Amir was able to atone for not helping Hassan. Amir has always been a coward. Since the day that he was born, he would run away from any trouble, or Hassan had to protect him. However, as soon as he finally realized that he had a "way to be good again" (pg. 192) he took the opportunity to finally do something. After traveling all the way back to Pakistan and meeting with Rahim Khan, he debated going to Afghanistan to save Sohrab under the guise that he would save him and then give him to another family who takes in refugees. Amir scours Afghanistan, travelling from Farid's house to an orphanage, then to a soccer stadium where he had to watch a man get stoned to death. He did all of this just to save Sohrab. Then after finally meeting the man who took Sohrab, he realizes it's Assef. Assef then tells Amir that they must fight for him to take Sohrab, and because he doesn't want to be a coward any longer, Amir says, "All right" (pg. 286). Then, after Assef is defeated, Amir can do nothing but worry about Sohrab's wellbeing, even when he himself is on the brink of death. Then, after Sohrab ran away, Amir panics and runs to find him as quickly as possible. Amir then finds out that this family he was supposed to give Sohrab to never even existed, but since Amir wishes to atone for his mistakes, he decides he will house Sohrab in his own home and raise him as his own. Then, after Sohrab's attempt on his life, Amir carries his body to the ambulance and stays with Sohrab the whole time. Amir was doing all of this on top of trying to figure out how they were going to get back to America. After finally getting back to America, Amir does as much as he can to make Sohrab happy again. The ending of the book signifies Amir's atonement the most as, while kite flying with Sohrab, "One corner of his mouth had curled up just so. A smile" (pg. 370) symbolising the hope for Sohrab's future, and the atonement he has earned for his misdeeds.