Lydia Chevalier was new to Forks, but immediately she could sense the presence of wolves and vampires; and they could sense her. The Cullen's fear they have an enemy, while the Wolves are sure they have gained a new ally.
Alex moves to Forks with her mom, Ashley, to get rid of the bullies. Ashley's best friends, Billy and Charlie lived there too. Alex becomes friends with them and met their friends. And that's when her life becomes a rollercoaster.