While Hosseini relies heavily on foreshadowing in his novel, irony does also play a major role, and it certainly advances the theme of betrayal and its effects on the betrayer and the betrayed. Here are several examples from Chapters 1-7:
1. Amir, who so badly wants to please his father, describes a photo of Baba, Rahim Khan, and him. In the picture, Baby Amir is clinging to Rahim Khan's finger instead of his own father's. The irony lies in the truth that even as an infant, Amir seemed to sense Baba's resentment toward him and almost a betrayal of him as his son. Later in the novel, the person whom Amir trusted most since infancy--Rahim Khan--is responsible for betraying Amir with the lie about Hassan's birth.
2. When Amir writes his first story about the man who discovers that his tears turn to pearls so he kills his wife, Rahim Khan points out the irony in the actual story. Ironically, though, an illiterate, uneducated Hazara (Hassan) finds the plot hole in the educated, gifted writer Amir's work. Hassan is the first and only one to identify the obvious solution to thecharacter's dilemma. Amir feels betrayed this time by himself and his lack of common sense but takes his frustration out on Hassan who was simply puzzled by the story's ending.
3. Amir's story also represents another form of irony. The idea that a young boy would write a story about a man murdering his wife in order to have more pearls foreshadows and ironically suggests that Amir is willing in real life to sacrifice someone else for his father's approval. He does just that with Hassan for the last fallen kite.
4. Another obvious example of irony is Baba telling Rahim Khan that he is afraid that Amir is too passive and that he will not stand up for himself. Baba thinks that Amir does not have a mean streak in him and never discovers just how cruel Amir was and could be to who was supposedly his best friend.
5. Ultimately, it is ironic that helping Hassan or obtaining the kite is the choice that Amir must make in Chapter 7. His whole short life up to this point was about earning Baba's approval and being jealous of the relationship between Baba and Hassan. Amir would not even have an opportunity for the last fallen kite if it were not for Hassan, but he does not recognize this truth. Rather, he chooses to betray Hassan to win Baba's approval for a short while. He spends the rest of his life trying to redeem himself for this one choice and the rest of Baba's life trying to find favor and recognition in his father's eyes.
Think about the section when Amir tells Baba to have plastic surgery. What happen next winter? The theme of betrayal happens often in the book showing one person going after their own selfish gains.