Like loyalty, betrayal also has a strong presence in The Kite Runner. In a way, betrayal is the driving force that pushes the plot further and makes the story come to life. Here are some quotes from the novel that I think portray betrayal.
I stopped watching, turned away from the alley. Something warm was running down my wrist. I blinked, saw I was still biting down on my fist, hard enough to draw blood from the knuckles. I realized something else. I was weeping. From just around the corner, I could hear Assef's quick, rhythmic grunts.
I had one last chance to make a decision. One final opportunity to decide who I was going to be. I could step into that alley, stand up for Hassan – the way he'd stood up for me all those times in the past – and accept whatever would happen to me. Or I could run.
In the end, I ran. (Chapter 7, pg. 137 -139)
In this quote, Amir witnesses his friend Hassan getting raped by Assef. This is what I think is the ultimate betrayal. He had a choice to run in there and stop it from happening, but he decided not to. On top of that he didn't tell Hassan what he saw, he remains silent, so I think he betrayed him again by not talking to him about it and by being a coward.
Early that spring, a few days before the new school year started, Baba and I were planting tulips in the garden. Most of the snow had melted and the hills in the north were already dotted with patches of green grass. It was a cool, gray morning, and Baba was squatting next to me, digging the soil and planting the bulbs I handed to him. He was telling me how most people thought it was better to plant tulips in the fall and how that wasn't true, when I came right out and said it. "Baba, have you ever thought about get ting new servants?"
Amir can't get over his cowardice. He can't handle anything that reminds him of it, so he pops that question to his Baba and Baba scolds him, threatening to strike him and tells Amir that Hassan and Ali are apart of the family.