Holden and Jem have several similarities. First, they are both in the young adult stage of life, transitioning between childhood and adulthood. Second, they both have a somewhat turbulent transition due to important events that are happening in their lives at the time. Both are, at times, forced into roles that are well beyond their years, as when Holden is on his own and living at a hotel and when Jem must serve as protector of Scout at the end of To Kill a Mockingbird.
However, there are several notable differences between the two as well. The most notable is that Jem has a father who is present in his life and who functions as a role model. Many of Jem's actions, and the subsequent person that he becomes by the end of the story, are as a result of watching the positive example of his father. Holden, on the other hand, has a largely absent father. Both function differently in their roles as brothers as well. While Jem positions himself as Scout's guide and protector, Holden is unable to protect Phoebe, and it is she who often comes to his rescue. Finally, the reader gets the idea that Jem's life turns out well in the end and that the personality he has forged stays with him in adulthood. On the flip side, the introduction that we get to Holden's institutionalization does not indicate that he has grown as a result of his prior experiences.
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