John Neville, as portrayed here, is all at once the soldier who has nothing left but the war, the man living on a desert island, the man who lost everything and doesn't have the courage to die. This is a man floating through his existence, who seems more content to keep the invading hemocyte hordes off his doorstep rather than go hunting and be rid of them once and for all. He has a dog, a nice hoard of technology at his disposal, and enough supplies and intelligence to survive. But the recurring question throughout the whole story remains "why"?
In a traditional action film, the answer to that question would be Cortman, the lead hemocyte with a definite superiority complex about what his kind has become. Indescribably strong, intelligent, and proud, Cortman was the first infected, and with a devil, the last remaining threat still alive, has found a purpose in Neville. He's a tempting and cool villain, with a few great, though underutilized subordinates at his wing, but Protosevich wisely doesn't let him steal the show, choosing instead to give him and him warriors just enough time to establish him as a serious threat.
No, in this story, the answer to that question isn't answered. As a matter of fact, the answer leads more toward "I don't think there is a reason. And I'm too scared to do anything about it." Neville is NOT an action hero. He has a hero's technology, but he is, in the end, a man, and having lost his family, his life, and being hunted by devils on a nightly basis, he is a man in a dark, silent hell. He risks his life to protect a dying dog, and breaks down when things become so immeasurably bleak. He turns to classical music rather than face the growing number of demons outside. And more than once, when things get too harsh in the thick of things, he turns the gun on himself. This is an actor's action hero. This is a character study above all else, and to inject that style of storytelling with this premise, it's a combination that almost can't fail.
