In the book The Giver, how does Jonas' character change?

Jonas begins in the story as an eleven year old boy, about to turn twelve. He believes, like all children he knows, that the community he lives in is a Utopian one, regulated perfectly so that everyone is happy and efficient in their lives. He is thoughtful, social, mature, and ready to live life the way he is "supposed" to.
When he is assigned the role of the new Receiver of Memory, all that changes. As he takes on more of the world's memories, Jonas, a twelve year old boy, becomes wiser and more emotionally aware than any adult in his community, except for the Giver. He begins to see through the lies of his community, and is overwhelmed by all the terrible things he knows are going on behind the scenes of everyday life. By the end of the book, Jonas is isolated and disillusioned, and knows that he can no longer stay in this dystopian nightmare. He does, however, retain his compassion.