Ghostaniaz: Son of Dragons by Tessa Dawn

Brutal, broken, and beyond redemption, Ghostaniaz Dragos, son of the most merciless and depraved dragon lord, has nothing left to lose. He lost his childhood—if not his soul—a long time ago, exchanging hope for defiance and love for wrath. And now that he is trapped in the Lower Realm, all bets are off.
Beautiful, bold, and beholden to Ghostaniaz for survival, Bethany Reid is in wicked dire straits of her own. She was abducted from a haunted house on All Hallows’ Eve, dragged before a garish, red velvet throne, and offered, like a lamb to the slaughter, to the immortal Pagan King of the underworld.
What neither Ghost nor Beth realize is that the Seven have manipulated everything.
Beth is Ghost’s preordained dragyra. His fated. His female. The only human woman in many lifetimes of suffering who might stand a chance of reaching his calcified, barren heart. She is his only hope for deliverance, even as he is hers.
Two unwitting pawns in a deadly game of chance, power, and dominion, Beth and Ghost must face their inner demons and overcome shadow-walkers, sin eaters, and mortal enemies alike, in order to find their way back to the Temple of Seven.

But time is not on their side.