How did Karim grow as a person throughout the book?

Karim, the novel's protagonist, is a seventeen-year-old boy from Beirut, Lebanon who settles as a refugee in Montreal, Canada. He is described as tall, dark, and handsome, with the air of a "desert prince." Karim begins the story reserved and cut off from the people around him; by the end, it is clear that he has survivor's guilt and is repressing the trauma of having lost Nada and Maha during his final days in Lebanon.