Then he'd taken the pomegranate from my hand, crushed it against his forehead. Are you satisfied now? He'd hissed. Do you feel better? I hadn't been happy and I hadn't felt better, not at all. But I did now. My body was broken-just how badly I wouldn't find out until later-but I felt healed. Healed at last. I laughed." (p. 252-53) The fact that Hassan had always been enamored by Amir is something that Amir acknowledged. He knew that Hassan had always loved him immensely. "Hassan and I fed from the same breasts. We took our first steps on the same lawn in the same year. And under the same roof, we spoke our first word.

Mine was Baba. His was Amir, my name." (p. 10)

The more Amir recalls the events of his past, the more readers can see how imperfect his character is. He was nothing like Hassan who would have given up his life had rape happened to Amir instead of him. But Amir hadn't done that and that cost Hassan a lot. Though the rape did not kill him but it certainly drove him out of his house as Amir couldn't bear to see him everyday without feeling immeasurable guilt inside. This was another cowardly thing to do- he didn't something worse to wash away something bad. But obviously that never worked.

Hassan had proved he was a far better human being than Amir and a definitely superior friend. He had saved Amir from bullies,...

That was the worst thing a person could do to another and especially to a deeply loyal friend. Amir suffered from guilt all his life till he saved Sohrab. But one wonders if such a victory could actually wash away the past, remove the guilt and cleanse the soul. It doesn't change the fact that Amir had betrayed Hassan and then instead of being more kind to him, he had driven him out of his house and deprived him of Baba's love.
Hassan was Baba's son and Amir came to know this much later in life. Had he known this sooner, he would have been more kind to Hassan. The contrasts between Hassan and Amir's personalities are enormous as they were two completely different people with completely different viewpoints. Hassan was loyal and simple, Amir was haughty and selfish. While Hassan could give his life thousand times over, Amir couldn't even do it once when his friend needed him. As a reader, I did not feel any compassion for Amir as he suffered from guilt. I was more concerned about Hassan and what became of him. Thus while the author thought Amir could be a more appealing character for readers, I choose to disagree strongly.

Reference:

Khaled Hosseini, the Kite Runner. Riverhead Brooks. 2003