Mark is the main protagonist in the novel. He is a teenager who survived a devastating series of solar flares and the aftermath, which included flooding, radiation, extreme heat, and devastating storms. Mark is around 15 when the solar flares occur and shows impressive growth throughout the novel, exhibiting bravery and courage that allow him to help others. When Mark looks back on his past, he remembers being a normal teenager whose biggest concern is finding a way to tell his neighbor that he has a crush on her. Within minutes, his world changes, and he is forced to grow up in a matter of hours as he faces the most difficult moments of his life.

Mark represents the classic hero archetype because he often puts himself in danger to protect others, especially Trina. This archetype is also evident when Mark proves to be the only character who figures out what is going on, and his effort are likely the first step in the search for a cure: If not for Mark understanding that Deedee is immune and his decision to send her to the PFC in Alaska, WICKED might not have formed, and the Glade project might never have existed.