in chapter 21, amir finallly sees Sohrab and realizes something about the taliban official. what is it? what is your reaction to Assef's reapperance as a talib? how does he justify his transformation?

He is Assef who is the rapist of Hassan and Sohrab. He justifies his transformation by horrible treatment at the hands of a prison guard when Assef was imprisoned and kicked until a kidney stone was dislodged. He feels justified in trying to rid Afghanistan of the trash he believes exists.