To Kill A Mockingbird Jem
Jem, like Scout, is learning a code of conduct from Atticus throughout the book. And also like Scout, Jem is intelligent, yet impressionable. The events that take place in Maycomb and uncharacteristically dark for the town, and a naïve Jem cannot fully comprehend them without Atticus' guidance. This guidance is what causes Jem to be the moody young man he is throughout parts of the book. He is learning to comprehend some of the darker aspects of human nature. When Scout asks him about weightier topics like racism and justice, Jem often becomes rude and angry. This is because Jem is currently trying to understand them as well, but finds the topics have no easy answers.
Toward the end of the novel, Jem becomes calmer and more realized. After all that has happened, Jem has matured and better understands his world. He now also concerns himself with being a gentleman, just like his father. Jem has grown both physically and emotionally throughout the novel and is close to being a grown man.