The pomegranate tree located on the northern hill of Baba's property is where Amir and Hassan would meet, play, and read books as children. Amir even recalls carving, "Amir and Hassan, the sultans of Kabul" into the side of the tree. The tree is significant because it symbolizes Amir and Hassan's friendship. Unfortunately, Amir and Hassan's friendship is ruined after Amir witnesses Hassan getting raped by Assef and does not intervene. Tortured by guilt, Amir cannot stand to be around Hassan and does not enjoy visiting the pomegranate tree.
In chapter 8, Hassan asks Amir to visit the pomegranate tree to read, and Amir agrees. However, Amir thinks that he's made a mistake visiting the tree and walks back home without reading to Hassan. Later on in the chapter, Amir asks Hassan to follow him up the hill so that he can read a new story to Hassan underneath the pomegranate tree. Shortly after arriving, Amir picks up a pomegranate and asks Hassan what he would do if he threw the pomegranate at him. Amir then hurls the piece of fruit at Hassan's chest and begs Hassan to hit him back. However, Hassan does not retaliate and even smashes a pomegranate over his own head. At this moment, the boys' friendship is over, and Amir proceeds to set up Hassan in an attempt to further distance himself.
In chapter 21, Amir returns to Kabul as an adult to atone for his sins by rescuing Hassan's son, Sohrab. When Amir arrives in Afghanistan, he travels up the northern hill near his old home and visits the pomegranate tree. Amir remembers that Hassan had written in his letter that the tree had not produced fruit in years, which symbolizes Amir and Hassan's broken friendship. Overall, the pomegranate tree is a symbol of Amir and Hassan's childhood friendship, and its health represents the state and nature of their friendship.