What is a theme from The Kite Runner?

One important theme in “The Kite Runner” has to do with individual identity and the degree to which our past actions determine who we are. In the case of Amir, his decision as a boy not to intervene when his friend Hassan is assaulted does, to an extent, determine his life path. Hassan’s assault is not “just” a case of bullying: it is an expression of a culture of violence that Amir and his father effectively reject when they immigrate to the U.S. So one way of understanding his immigration to the U.S. and, in fact, his adult career as a novelist is to see it as way of ignoring or retreating from some uncomfortable truths about Afghanistan. Both Amir’s failure to help Hassan, and his life in the U.S., by this reasoning, are expressions of a kind of cowardice.
The turning point for Amir is his discovery that Hassan was his brother. This is significant for several reasons—first, it changes how Amir understands his father and his motivations. Second, it casts his failure to help Hassan, who, he learns, has died and left an orphaned son behind in Afghanistan, in a completely different light. What he had thought of as a kind of personal failure he now understands as a kind of family betrayal. His guilt, and his desire to redeem himself, and his sense of a new bond with Hassan, lead him to return to Afghanistan and adopt Sohrab.
It is true that from Amir’s point of view his failure to help Hassan was a decisive moment. As readers, however, I think our understanding of the event is a little different. Amir’s cowardice ultimately made him into the man who was able to rescue Hassan’s son. That is, far from making him into a coward, in the end this moral failure provided a catalyst for the kind of reflection he needed to do to more fully understand himself, his father, and his culture.