1. Baba's Betrayal of Ali:
* The Act: Baba conceals the truth about Hassan's parentage for years, leading Ali to believe he is Hassan's father. This is a monumental betrayal of trust and loyalty, especially considering Ali's devotion to Baba and their long-standing friendship.
* The Impact: This betrayal has devastating consequences for Ali. It contributes to his feelings of inadequacy and inferiority, and it leaves him heartbroken and disillusioned. It also creates a complex dynamic between Hassan and Sohrab, as Hassan's true parentage shapes his life and his relationship with his son.
2. Amir's Betrayal of Hassan:
* The Act: Amir witnesses the assault of Hassan by Assef and chooses to do nothing to help him. This act of cowardice is rooted in jealousy and insecurity, and it directly contributes to the pain and suffering that Hassan endures.
* The Impact: This betrayal leads to a deep sense of guilt and shame for Amir, haunting him for years to come. It shapes his entire life, driving him to seek redemption and to atone for his actions. The impact on Hassan is devastating, leading to his eventual departure from the home and his tragic fate.
These two acts of betrayal form the core of the novel's themes of guilt, redemption, and the complex nature of friendship and family.