Dominion by Bentley Little

When Dion Semele moves to Napa, all he wants is to fit in. Something really strange is happening to Dion and odd-girl-out Penelope understands completely.

Something is happening to her, too. You see, they were made for each other.

As Dion's new life becomes a twisted nightmare, he learns that maybe he and Penelope were made to raise hell together, too.

Soon they are caught in a battle for control of their souls as malignant forces plunge Napa into an abyss of debauchery and blood.