The Host by Stephenie Meyer

In the future, Earth has been invaded by an alien life form called Souls, parasites who require a human body in order to survive. When Melanie, one of the few remaining human resistors, is captured Wanderer, a legend among her species, is inserted into Melanie's body. Wanderer finds, however, that unlike most hosts, Melanie refuses to fade away. As Wanderer and Melanie battle for control of the body they share, Wanderer becomes overwhelmed by Melanie's memories and emotions and becomes attached to the family Melanie left behind. Meyer has stepped away from the world of vampire romances and has created an intense romance of another kind. A wonderfully crafted and interesting cast of characters will engage the reader from the first page to the end. The perfect amount of suspense and tension will push readers through this monsterous 600+ page tale and leave them wanting more. Though published for adults, teen fans of Meyers will be clamoring for it- even teens who don't read science fiction. It is a great book for a discussion on relationships, humanity, and survival.