The passage is significant on many levels including, as other educators have noted, that it represents the first sign of what will hopefully be a bond between Amir and Sohrab and that Amir has been able to break through to Sohrab through their shared activity of flying the kite. When the reader first is introduced to Sohrab, he is wearing heavy makeup that underscores his role as Assef’s captive sex slave. Not surprisingly, the boy is in despair and has nearly given up all hope before Amir’s arrival. That is why when after their escape Amir tells him that he might have to be placed in an orphanage while they work on getting to the United States, Sohrab attempts suicide. He knows what happened to him the last time he was placed in an orphanage.

Even though Amir and Soraya want Sohrab to know that he is safe living with them as their adopted son, the nightmare of his experiences in Afghanistan hangs over him, and he is unable to escape it. He is not a child as other western children are; his life up until now has been a series of horrific events, beginning with the murder of his parents and his being seized by Assef at the orphanage. When he finally smiles, even slightly, it is the first sign that perhaps he can overcome all that he has been through and learn to trust Amir and Soraya, to love them, and perhaps to begin to take pleasure in life.

The smile is also significant because it occurs when Amir and Sohrab are flying kites. This parallels the bond between Amir and Hassan, Sohrab’s father, as it was a favorite activity of theirs. There is a sense of nostalgia for Amir, and we can imagine Sohrab picturing his father flying kites with Amir when the two were boys. The smile is also significant because it parallels the frequent references to Hassan’s beautiful, guileless, and almost ever-present smile.

While this passage symbolizes hope, it also stands for possibility. The Kite Runner deals with a lot of dark themes, including many that children⁠—anyone, really⁠—should not have to deal with in an ideal world. Amir always faced the very real chance that even if he somehow managed to find and rescue Sohrab, the boy he brought home would be nothing more than a shell. Until this scene, it has almost seemed to be so, to the reader and to Amir both. Sohrab does not smile and does not appear to enjoy anything. No one would be particularly surprised if he was broken by his experiences, but the novel offers a silver lining right at the end, in this passage.

The passage offers proof of the resilience of a child's spirit. Sohrab could almost be considered lucky, since a fair share of his miseries befell him when he was just young enough to be able to forget. Seeing him smile makes Amir hopeful as well⁠—hopeful that Sohrab will be able to put his troubled past behind him, just like he himself is trying to do. Forgetting entirely is, perhaps, impossible, but there is still something to be salvaged⁠—something that could be built into a fairly normal life. The passage states that, although the can't be erased, it's not too late for either of them to have a future.

In the last scene of the story, Amir participates in an impromptu kite-fight at a local park, and Sohrab, surprisingly, tags along. After Amir cuts his opponent's kite down, he looks back at Sohrab before running after the falling kite and sees his adopted son crack a smile. Sohrab's smile is significant because it represents hope in a better future and the beginnings of a happy life in America. Ever since Sohrab arrived in America, he has refused to speak, and his oppressive silence has consumed Amir and Soraya's home. His traumatic experiences in Afghanistan and Pakistan have negatively affected his outlook on life, and it seemed as though he would never recover. However, Sohrab's brief smile during the kite-fight can be viewed as a silver lining. Hosseini ends his novel on a hopeful note: Sohrab's brief smile contains a hope that he will recover and experience a fulfilling life in America with Amir and Soraya.

The significance of the quote is that it represents hope for Amir and Sohrab.

This quote is the just before the last lines of the novel The Kite Runner. Amir and Soraya have successfully brought Sohrab back to the United States and are trying to heal as a family from the events of the book. Despite the fact that he now lives in safety, Sohrab doesn't smile. He doesn't laugh. He's been through too much to be a happy child.

However, when Amir, Soraya and Sohrab go to a gathering at Lake Elizabeth Park in Freemont just after the Afghan New Year, there are kites to fly. Amir tells Sohrab that Amir's half-brother, Hassan—who is also Sohrab's father—was the best kite runner in Wazir Akbar Khan and maybe all of Kabul. After finally convincing him to fly the kite together, Sohrab smiles for the first time.

It doesn't mean that the wounds of the past are healed. As Amir says, winter only gives way to spring slowly. But it does mean that Sohrab is beginning to heal and the three of them will be able to move on as a happier family.

These quotes, coming from the final page of The Kite Runner, detail the breaking of the ice between Amir and his nephew, Sohrab. Sohrab, who refuses to speak and never smiles after returning with Amir to California, has agreed to allow Amir to run the kite for him--just as Sohrab's father, Hassan, had done so many times before for Amir. Sohrab acknowledges Amir's request with just the slightest hint of a nod, but for Amir, it is a giant leap forward in his relationship with his nephew. The acceptance by Sohrab does not make up for any of Amir's past sins, nor does it mean that Sohrab has recovered from the traumatic experiences he suffered in Afghanistan. But it is a start, and author Khaled Hosseini symbolically compares it to the melting of a single snowflake, the beginning of a new spring. Amir does not waste the moment: He runs the kite for his nephew, taking Hassan's place as the kite runner; and he runs with a smile on his face, just as Hassan had always done--another step in the atonement that Amir seeks for his past transgressions.