This is above all else a story of redemption as both Baba and Amir, in their own way, have to struggle to make ammends for their past misdemeanours. For Baba, his crime was having slept with his best friend's wife. This secret is only something that emerges after his death, when Amir goes to Pakistan and finds out the truth of his relationship with Hassan from Rahim Khan. He discovers that Hassan is actually his half-brother thanks to his father's adulterous relationship with Ali's wife. Baba sought to make ammends by bringing up Hassan and Amir to be brothers and doing what he could to provide for them.
It is interesting that both father and son are placed in a relationship where they have more power, and which they abuse through that power. Just as Baba abuses his friendship with Ali, Amir abuses his friendship with Hassan by not intervening when he is being raped by Assef. Eventually, what he realises he has to do, is to return to Afghanistan and rescue Hassan's son, his nephew. The process he goes through to be successful in this aim involves considerable suffering on his own part, as he is beaten up very badly by Assef, but eventually his redemption is shown in Chapter 25, when he flies a kite in America with Sohrab, and, for a moment, is transported back to much happier times:
Next to me, Sohrab was breathing rapidly through his nose. The spool rolled in his palms, the tendons in his scarred wrists like rubab strings. Then I blinked and, for just a moment, the hands holding the spool were the chipped-nailed, calloused hands of a harelipped boy. I heard a crow cawing somewhere and I looked up. The park shimmered with snow so fresh, so dazzling white, it burned my eyes.
The way in which Amir returns to a younger version of himself and Sohrab becomes Hassan, and they are in a snow-covered Kabul, shows the extent to which he has been able to gain a measure of peace at this point in the narrative, compared to his guilt-ridden presentation in previous chapters. At the end of this novel, Amir is a man who is shown to have gained redemption through his rescue and adoption of Sohrab.