The main character in Hatchet, Brian Robeson, is a thirteen-year-old boy from New York City. This novel primarily deals with themes of man and nature as well as of self-awareness and self-actualization, mainly through Brian's experiences living alone in the wilderness. Therefore, he is essentially the only principal character. Brian's parents have just recently divorced, and this conflict between them has deeply affected Brian and his sense of stability. His sense of self has been disrupted by his parents' split, and he bears the burden of "The Secret," that is, the knowledge that his mother is having an affair with another man.

Brian is an exceptionally dynamic character. While he demonstrates vulnerability, frustration, and anger at the beginning of the novel, his experiences in the north woods of Canada alter his perspective forever. He learns lessons and adopts qualities that are relevant not only to wilderness survival but also to life as a whole. Patience, observation, an appreciation for the natural world, and a newfound connection between mind and body all contribute to Brian's character development and to his emerging manhood.

Brian matures through his new ability to be patient. Setbacks that would have immobilized the "old Brian," the Brian at the start of the novel, later become manageable. He learns to control his temper when he realizes that his frustration and hopelessness does not help his family situation. When he works to complete a specific project, such as hunting or building a shelter, he learns by trial-and-error. If certain methods fail to accomplish the job, Brian learns from his mistakes rather than dwelling on them. He modifies his approaches to the problems of survival in the woods and tries again and again until success comes to him.

Brian also develops a keen sense of observation, using his senses not only to survive, but also to grasp the beauty of nature and its sights and sounds. The constant stimulation of the city had dulled his senses. The relative silence of the woods allows him to hear anew and to pick up on millions of sounds now that he has learned to hear them. The scenery of the woods and the lake seem a first "a blur," but later strike him as immensely beautiful. He also uses his honed senses to survive. For example, at first he cannot seem to locate the foolbirds he attempts to hunt; they pop up out of nowhere surprising him with their presence. After he trains his eyes to spot their outline, however, he attains success in lunging at them with his spear. Brian also develops an ability to hear the slightest noise. He adopts a lighter sleeping pattern in which he awakes at the noise of potential animals around his shelter. In addition to his senses, Brian develops a sort of "sixth sense" in the woods. Almost animal-like, his instincts become more acute. There are many instances in the book where he "senses" danger before it arrives.

Brian also develops a new appreciation for the natural world and the self- sufficiency that is necessary when the conveniences of the urban environment are far off. He respects the animals that share the woods with him, and begins to regard himself as simply another creature of nature striving to survive. He knew little of nature before the plane crash, and he picked up most of his knowledge from books, school, or the media. He found that actually experiencing nature first-hand was a far different and more vivid experience than any book or movie.

Brian arrives in the woods a slightly pudgy boy, accustomed to hamburgers and his mother's cooking. In the woods, however, on a diet of berries, fish, "foolbirds" (as he calls them), and rabbit, Brian's stomach shrinks and he becomes all lean muscle. When he catches a glimpse of his reflection in the lake, he remarks on how different he looks. His looks are not the only or the most profound change. The real change has occurred in his mind and in his outlook on life. He realizes that being in the natural environment and having to be concerned about physical needs has brought his mind and body to a closer harmony. As his English teacher used to tell him, his mind has the power to dictate his body's behavior. As long as he remains positive and active, he can accomplish virtually anything. This link between mind and body is a new sensation for Brian, and a sign of his increasing comfort with nature.

All these changes signify Brian's emerging manhood, a major theme in the novel. At the beginning of the novel Brian defines himself through his parents, and for this reason the divorce presents a particular kind of pain for Brian. He sees instability in his future, no longer able to take solace in his identity with his family. At thirteen years old, Brian does not feel quite ready to define himself as an adult. The plane crash and his subsequent stay in the woods force him to come to terms with this broken sense of identity. The challenge of survival alone in the woods leaves Brian with a choice: grow up and be tough, or die. Brian accepts the challenge and emerges from it having experienced the responsibilities and pressures of adulthood.