Best Left in the Shadows Series by Mark Gelineau, Joe King

One city. Two worlds. The King of Aedaron reigns in splendor, while far below, in the streets and alleys of the underworld, a different kind of king emerges. Alys and Dax have always been caught in the middle. Once they fought for love, and their worlds tore them apart. But now as they are forced back together, they must choose whether to fight once again. But for what? And against whom? In the world of Lowside, nothing is as it seems. Even each other.