We find the answer to this question in Chapter 7, which features the kite tournament and also the terrible, shocking aftermath, that will change the fates of Hassan and Amir and their relationship for ever. What is key to realise in the early stages of this novel is how the relationship that Hassan has with Amir is presented. Although Amir is somewhat ambiguous in his feelings for Hassan, treating him half of the time as a servant and the other half as a friend, to Hassan, Amir is a brother to be loved and respected with a love that is self-sacrificial in the extreme. This is why, after their triumph in the kite competition, he is eager to make sure his master triumphs in the kite running as well, and decides to run for the blue kite, the most prized kite to gain. Note how his love for Amir is made clear when he leaves to pursue it:
He was already turning the street corner, his rubber boots kicking up snow. He stopped, turned. He cupped his hands around his mouth. "For you a thousand times over!" he said. Then he smiled his Hassan smile and disappeared around the corner.
Note how his words show and express his devotion and love. The author uses these words at the very end of the novel in a very different but also similar situation to act as a symbol of the same love and self-sacrifice, but now between Amir and Hassan's son.