The Demon That Saved Him

We all know the stories. Where the dark and mysterious boy is from " the dark " side. And the perky, happy girl is from the "light" side. She's good, he's bad.
Well, this is not one of those. If anything this is the exact opposite. Their names are Lillith Shade, and Lucas William.
But to make things worse, their the heirs to the Demon and Angel kingdoms. Demon Princess Lillith and Angel Prince Lucas.