Jonas is developed as a character because he goes from being a faceless observer of his community’s rules to a questioner and ultimately a deserter.
When the story begins, Jonas is a simple eleven year old boy who does what he is told and thinks what others tell him to believe. He has no idea that there is anything wrong, and he fully supports his community’s precepts.
However, Jonas is different. The narrator introduces us to this idea in small ways at first. For example, Jonas does not dream like everyone else, and he does not want to share his feelings.
Jonas sighed. This evening he almost would have preferred to keep his feelings hidden. But it was, of course, against the rules. (ch 1, p. 9)
Jonas’s feelings this time were fairly simply, but Jonas is already showing signs of a need to change. He wants his privacy, yet it never occurs to him to not tell, or to lie.
When Jonas is selected as the new Receiver of Memory, he realizes that he is different. He recognizes events from his life, such as a time when he thought he saw an apple change color, as evidence that he is different. Once his training begins his new suspicions are confirmed. Jonas is not like everyone else.
Jonas develops a relationship of trust with The Giver, the old man to whom he is apprenticed. Before long, he sees that the world has not always been cold and emotionless. He learns the concepts of love, family, and choice. He longs for the days when he could have had these things.
When Jonas sees his father kill a newborn baby, he realizes that this kind of thing is nothing out of the ordinary. The fact that Jonas’s father does not see it as immoral deeply hurts him. From that point on he has lost faith in his father and his community. He decides to leave, hoping he can escape to a better place.
Jonas's development is slow and steady. It does not happen overnight. In fact, Jonas is the very definition of a dynamic character. The person he is at the end of the book is very different than the person he was at the beginning. His experiences have changed him. They have made him wiser, but they have made him sadder too.
Lowry, Lois (1993-04-26). The Giver (Newbery Medal Book). Houghton Mifflin Harcourt. Kindle Edition.