One of Hassan's defining physical features is his cleft lip that Baba pays to have surgically repaired. The scar from the surgical procedure remains and corresponds to the scar on Amir's upper lip that develops following his violent altercation with Assef. After Amir narrowly defeats Assef and escapes with serious injuries, he is left with a scar on his upper lip, which symbolically represents his sacrifice and atonement for his past sins. Hassan had always sacrificed and protected Amir as a child, but Amir did not return the favor. Later in life, Amir finds redemption by saving Hassan's son, Sohrab, from Assef, who is a maniacal Taliban official. In order for Amir to atone for his sins, he has to physically suffer and sacrifice his own life to save Sohrab. The scar symbolically represents Amir's sacrifice and serves as a reminder of all the times Hassan protects him during their childhoods.