Eclipse presents being good or evil as a personal choice, not an unchangeable state. Although vampires are born to thirst for human blood, the Cullen family has chosen a different life. Their alliance with the werewolves shows that natural enemies can unite to fight for good against evil. At the same time, they struggle with their embedded tendencies to think of each other as evil. Carlisle spares the life of the newborn vampire Bree, because he believes she didn't realize that she wasn't taught that good can exist. Jane kills Bree, because she believes that breaking the rules is an evil deed that can't be redeemed.