Shadow Allegiance — Lacy Yager

They were her enemies. Until she became one of them. A Chaser born to kill vampires, sixteen-year-old Rachel Campton has grown up in her older brother's shadow. Until she wakes up a vampire, her own mortal foe. She's stronger, faster than her human self, but haunted by bloodlust and the loss of her beloved younger sister. Friendless and lost in enemy territory, Rachel must rely on Alex Wellington, a former nemesis and centuries old vampire who looks like a college football player. As Rachel goes deep into vamp territory, she learns there is more to the vampire life than killing humans. She also discovers another side to Alex. He is more than a murderer, he is someone that she starts to fall for. Rachel faces the ultimate choice--her new life and unexpected love or the family she left behind, the family that may now want her dead.