In the early pages of the novel, Cassie tells us that she has changed from the way she used to be—that she has become a killer. Given the context in which Cassie finds herself—kill or be killed—this increases our sympathy for Cassie rather than diminishing it. She is a teenage girl in unbelievable circumstances, and moreover she is an admirable teenage girl in these circumstances because of the way that she responds to things. She endures and overcomes intense physical pain because she loves her brother and wants to get to him; she does not give into loneliness, depression, or hopelessness, although she deals with her situation with a kind of gallows humor that illustrates her intelligence and endears her to the reader.
Like Cassie, Ben is a fairly average American teenager—endowed with a few particular gifts, like good looks and athleticism. After the invasion, however, Ben is transformed into a warrior. Ben differs from Cassie in that he has actually lost his entire family; thus, he is at first more vulnerable to hopelessness. Since he is racked with guilt about his failure to save his younger sister, Ben is haunted and defeated. It seems he would actually welcome death, and understandably so; after all, what does he have left to live for?
Ben’s feelings of guilt and depression make him especially susceptible to Vosch’s brainwashing tactics. Vosch plays on Ben’s desire for revenge—the last powerful emotion left to a young man who has lost everything else, it seems. In this sense, Vosch unwittingly saves Ben and turns him into a formidable enemy. As the old adage goes, “What doesn’t kill us makes us stronger,” and this proves true for both Cassie and Ben. Ben’s coming-of-age happens during an alien apocalypse, rather than on a high school football field; ultimately, this