Why is the quote below important? What's the significance of it? Also, how does it develop the plot and characters?
“I envied her. Her secret was out. Spoken. Dealt with. I opened my mouth and almost told her I’d betrayed Hassan, lied, driven him out, and destroyed a forty-year relationship between Baba and Ali. But I didn’t. I suspected there were many ways in which Soraya Taheri was a better person than me. Courage was just one of them"
The passage shows Amir's emotional reaction after Soraya had told him of her past. She had rebelled and left her father's home to live with a man outside of marriage. This was an act of great shame within the culture of their Afghan community, and it took great courage for her to tell Amir this truth about herself, for she believed he would no longer want her as his wife.
Amir's reaction shows that he still lacks the courage to speak of what he had done as a boy, and he still feels the weight of his cowardice. His opinion of himself is still quite low. He has done nothing in the intervening years to free himself of the guilt he has suffered as the result of his betrayal of Hassan. Amir's choosing to return to Afghanistan during a time of great danger in the country in order to deal with this past makes up most of the remainder of the novel, but at this point in the story, he has not yet developed the courage to do that.
Soraya is the young woman Amir and his father met at the Afghan flea market in California; as Amir, she was in the habit of going there with her father to help him trade goods at his stand. Soraya had run away with a man when she was just a young girl and although she had been brought back under the parental roof, she had been "soiled" since she was no longer a virgin.
When Amir begins to take interest in her, she confesses to him her past, something Amir himself has been unable to do. He admires Soraya for her sincerity, recognizing that she is a cut above him in worth. Amir understands that truth is intrisically related to honour, and by choosing to live in transparency (even if it meant being stimatized), Soraya is at least at peace with herself and others.
Amir manages to win Soraya's love and takes her for his wife after a very traditional courtship.