Answer:
However, while Jeremy Atticus Finch, better known as Jem, was not the primary character in Harper Lee's novel To Kill a Mockingbird (also known as To Kill a Mockingbird), he is the character who is the most dynamic because of the huge changes that occur in his life during the tale. Jem and his younger sister Scout are extremely similar in appearance at the beginning of the novel. They are both hot-headed and frequently make impulsive actions that get them in danger; for example, trespassing on the Radleys' porch and nearly being killed by Nathan Radley as a result of it. In contrast, as the tale continues and the children become aware of Atticus's involvement in Tom's trial, tensions begin to emerge between Jem and Scout. Scout maintains her hot-headedness and has become enraged with anybody who has insulted Atticus during the trial, but Jem maintains his cool, as though he understands that being enraged would be counterproductive. He also begins to ponder more about what is going on in Maycomb and what the people who live there are actually like as a result of his observations. Combined with his increased capacity to think critically under pressure, Jem's ability to maintain his composure under pressure demonstrates Jem's maturing maturity.
Despite this maturity, Jem shows signs of immaturity by losing his cool with Mrs. Dubose, who harasses and criticizes Atticus on a regular basis and ruins her flowers in the process. Following his being forced to pay back his vandalism by reading to Mrs. Dubose, who tragically passes away due to her advanced age, Atticus teaches Jem about what true courage is, and how he can learn a lesson from Mrs. Dubose, who gave up her Morphine addiction in order to die "free," despite the fact that it caused her a great deal of pain. When Jem realizes what she has learned, she grows more mature as the day of Tom's trial approaches.
If and when the trial eventually takes place, Jem witnesses first-hand the bigotry and hatred that pervades Maycomb and is appalled by it; yet, he maintains optimism that Atticus will be able to convince the community of Tom's innocence. When the judgment is read and Tom is found guilty, all of those dreams are dashed to the ground. Jem feels disturbed at learning that the inhabitants of Maycomb are capable of such evil behavior, and his viewpoints shift. Jem grows more cynical as time goes on, and he begins to understand why Boo Radley chooses to remain inside since the world in which he lives is so harsh.
When Jem and Scout are attacked by Bob Ewell at the very end of the novel, all of Jem's maturity is put to the ultimate test. Jem protects his sister with a knife against a mature guy, resulting in his arm being broken and him being knocked unconscious, despite the fact that he is still a child himself. That Jem transformed from an immature youngster who bullied his shy neighbor to a caring elder brother who sacrificed his life to defend his sister is demonstrated in this pivotal moment of the narrative.