I Am Legend by Richard MathesonRead about the other entries on the list.
Robert Neville is the sole survivor of pandemic which turned the rest of the human population into, essentially vampires. He researches the disease and how to kill the infected. He barricades When he meets Ruth, who appears to be uninfected, he's extremely suspicious of her. And he appears to be right, since she later admits to him that she is. The world is now inhabited by the infected, and they hate and are scared of him just as he is of them.
The Lesson: It's important not to assume that the group you fear and hate are treating you badly just because they're evil or wrong. They can be coming from a very similar place to you.
I Am Legend is among Jennifer Griffith Delgado's eleven most mind-blowing surprise endings in science fiction and fantasy literature and Kevin Jackson's top ten vampire novels.