In Among the Hidden, Haddix illustrates the transformation of Luke Garner from a scared and helpless child into a self-assured and aware young adult to delve into several significant themes. Unlike typical utopian and dystopian narratives that depict fictional societies, this novel focuses on the growth of a twelve-year-old boy as he comes to understand the society he inhabits, the freedoms he has lost, and the sacrifices involved in striving to make a difference. Luke faces the developmental challenges common to all young adults, but he does so in a dystopian setting where his very existence is forbidden.

At the story's outset, Luke's mother urgently directs him to come inside and hide because the government has started cutting down the trees beside their home, which had previously concealed Luke when he was outdoors. Until he turned six, Luke’s family shielded him from the truth of his uniqueness, and he believed that reaching that age would allow him to explore the world like his brothers. Although he has always been the only one in his family to question "why," he has learned to find some contentment in his life as he has grown older. Being a "third" child, he has always held a special place in his mother's heart; she chose to keep him despite the government’s laws. However, as the government removes more of the trees, Luke starts to understand that he is not just different from his family but is actually illegal—"There is a law against Luke." The government's actions in cutting down the woods and forcing the sale of the family's hogs confine Luke indoors, leading him to become more isolated as he distances himself first from his brothers and father, then from his mother. At a time when most adolescents begin to gain independence by exploring the world, Luke isolates himself by retreating to the attic.

Jen Talbot, who defies gender norms with her bold and assertive demeanor, exposes Luke to an entirely new reality, to the point that when he returns home, he becomes indifferent to his family. Jen takes pride in being as rebellious as possible without being caught; she actively engages in an online chat room for hidden children and even posts antigovernment remarks on government websites. Through Jen, Luke learns not only about rebellion but also about wealth, poverty, divorce, gender selection, and even potato chips. Jen enlightens him on the history of the population laws, the government's corrupt and manipulative tactics, and provides him with new books and computer printouts to read.

Jen introduces Luke to two crucial concepts: friendship and critical thinking about the world. When Jen intentionally cuts her hand to conceal Luke's presence from her parents, he is astonished by her willingness to do such a thing for him, especially since they have just met. Later, when Jen seems to be absent, Luke realizes he now has someone else to care about besides himself. After diligently reading the books and articles Jen provides, Luke starts questioning what the truth is, as all the materials seem accurate yet contradict one another. Additionally, when he notices that the Barons possess wealth and influence but seldom eat meat while his family, though impoverished, enjoys hearty meals daily, he begins to perceive the world's complexities. Ultimately, when Jen is killed by the government during a protest at the White House, Luke understands that Jen was naive and gullible. She underestimated both the fear experienced by hidden children and the government's power, realizing she was as manipulated as everyone else.

Jen and Luke have their most significant disagreement about whether it is essential...