Baba was lonely and very dependent on Hassan even though Hassan was his servant and he was a great man. He considered Hassan a brother even though he lived in a smaller place outside their home. Hassan also covered for Amir even when Amir did him a terrible wrong by sleeping with his wife. Hassan did not expose him but rather continued to faithfully serve him.
In the same way, Amir and Hassan had a brotherly relationship; however, with Hassan serving Amir even when Amir did not stand by him when he was raped and often fooled him by pretending to read him stories but actually making them up. The last straw was when Amir framed Hassan, and Hassan's father could take it no longer so that they left. However, all this time HAssan had no bitterness toward Amir. He faithfully loved, served, and forgave Amir even until his death although they were very far apart.