The 3rd wheel lovers

when the cullens adopt a girl at the age of 13 everyone has a match except her. She constantly is looking when one day she finds a boy named Leo valdez.they seem the perfect match. but the whole summer he disapears and comes back with old bruises an scratches that weren't there when he left. he tells her about his 'back round' (aka a demi-god). alice has visions of him becoming a vampire. but what will the Voltaire do? Is he too powerful to be a demi-god AND a vampire?