Moon Rise (Unbidden Magic) (Volume 2)

Allie Emerson is the girl voted least likely to save the world. At Peacock Flats High she can barely handle the bullies and drama queens; her mom's a loser and Dad's a no-show; so after an elderly neighbor gave her a magical moonstone necklace and helped her locate her mystically mysterious father, and Allie discovered her power to fight evil Trimarks, she thought that was plenty of excitement for one teenage lifetime. But now there's more trouble: more Trimarks, and a gorgeous new guy at school, who just happens to be half-demon. Sequel to Moonstone.