He is Amir's playmate and servant; As well as Amir he is a Hazara and Shi'a Muslim; his father is Ali.
Hassan is the most loyal and devoted servant Amir had ever had. He was born with a cleft lip. He and Amir were nursed by the same woman, and without knowing it, they became half-brothers. As a servant, Hassan wasn’t very intelligent, but nevertheless, he was very smart and stand-ups for others. Also, one day in Kabul were competitions for best kite runner, and Hassan won it without any problem.
Hassan always likes Amir, and saw him as a good friend; he always acts with him like with a real brother. Anyway, Amir didn’t feel the same. A lot of critics said that Hassan is even too good to be real. And to be honest, we can’t judge them for that summary. Because even after he is betrayed by Amir, Hassan continues lying for the person he considers his friend.
Hassan proves that he is a very good friend for dozens of times. He always protected Amir when someone wanted to attack the last. Also, he was a very good listener, when someone needed his help he was there for that person. His most visible characteristics are bravery, selflessness, though his smarts are more instinctual than bookish, largely because he is uneducated. Being a very poor ethnic Hazara, he becomes a victim of racism; he finds it hard to have a home anywhere. He knows that his real father is Baba, but no matter what he loves Ali, knowing that the last is the one who grows him up and acts like a real father with him.
Also, being a child he was raped, it is really awful, that is why the author of the text didn’t take this story through all the text. He told about it and left us with emotions we feel to understand what a hard life the child had, has and will have.
Hassan in the Essays