In The Kite Runner, what are two incidents that depict a significant development of characterization?

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.