Both Amir and his nephew, Sohrab, change significantly following their confrontation with Assef in Chapter Twenty-Two of The Kite Runner. Though Amir has changed drastically following his arrival in America, he is still haunted by the guilt he feels after his betrayal of Hassan. He knows that returning to Afghanistan and finding Hassan's son, Sohrab, will be the only way he can ease his conscience and retain his nang and namoos. Amir's personal courage reaches its height when he faces off with Assef. Instead of cowering as he did in the past, he insults Assef and demands that he release Sohrab to him. The beating Amir takes at the hands of Assef only makes him laugh, and the pain--and the knowledge that he had stood up to his demons at last--is what cleanses his conscience. Amir has finally become a man.
Sohrab, too, changes in this same room where his father often visited Baba and Amir. Long a sexual play toy of the Taliban, Sohrab makes a stand against them when he pulls his slingshot to defend Amir (who he does not realize is his blood relation). He only recognizes that someone at last is willing to stand up for him and take him away from his horrible existence. When he lets fly, and the brass ball replaces the eye that once belonged to Assef, Sohrab, too, frees himself of his tormenters--if not of the memories which haunt him as well.