The image at the very beginning of The Kite Runner is the narrator remembering when he “came of age”, describing himself kneeling next to a crumbling brick wall.
I remember the precise moment, crouching behind a crumbling mud wall, peeking into the alley near the frozen creek. (ch 1)
Amir reflects that he has learned that you can’t bury the past. Opening the book with this image is significant because Amir has to confront the difficult things that have happened to him, and the situation he left behind in Afghanistan now that he is comfortably in America.
Beginning the story with this image prepares the reader to be transported to a harsher time, and a time when Amir had a difficult life. It is foreshadowing of the story the reader is about to experience.
At the beginning of the novel, the narrator shows an image of him "crouching behind a crumbling mud wall, peeking into the alley near the frozen creek."
This image is a motif which supports a major theme (in the novel) about the need to atone for past betrayals. The mud wall that overlooks the alley is where Amir hides as he witnesses Hassan's horrific rape in the alley. So, both the mud wall and the alley represent a scene of betrayal as well as sacrifice.
Additionally, Amir's flashback memory of the fortune teller during Hassan's rape is noteworthy; in the memory, he remembers how he and Hassan were both nursed by the same Hazara wet-nurse and how "they say there is a brotherhood between people who've fed from the same breast." Later, when Hassan is raped, his look is that of a lamb sacrificed during Eid. The image of innocence is juxtaposed against the image of brutality in this mud wall/alley scene; it is betrayal fueled by cowardice which leads to this innocent sacrifice.
It is interesting to note that, in Amir's memory, a rooster crows on the other side of the wall, as he pulls his hand away from the fortune teller's grasp. In Islam, the prophet Muhammad advises: "When you hear a rooster crowing, then ask Allah for His bounties, for it has seen an angel, and when you hear a donkey braying, then seek refuge in Allah from Shaitan, for it has seen a Shaitan." (from Best Times to Make Dua or Supplication). In the story, the rooster crows because it has seen an angel, Hassan, who has given himself as a sacrifice for Amir. While the rooster's significance in Islam permeates this scene, we must remember also that, in Christianity, the rooster plays a significant role in the scene of a profound betrayal: a rooster crows after Peter, a disciple, betrays Jesus three times.
So, the image of Amir crouching by the mud wall as he looks into the alley is a powerful one. That location is both the scene of betrayal as well as innocent sacrifice, and we remember it as Amir travels the tortured path to his supposed redemption.