Throne of the Fallen (Prince of Sin Book 1) by Kerri Maniscalco

She didn't want Prince Charming. She wanted the demon.
 
From #1 New York Times bestselling author Kerri Maniscalco, Throne of the Fallen is a seductive new standalone novel set within the Kingdom of the Wicked world.
 
A wicked prince. A fallen painter. Let the games begin...
 
The Prince of Envy has never claimed to be a saint. But when a cryptic note arrives at his demon court, signalling the beginning of a deadly game, he knows it will take more than a hint of sin to win. Riddles, hexed objects, anonymous players, nothing will stand in his way.
 
Camilla is an artist with troubles of her own: a desperate mistake has landed her in debt to a notorious rake. Threatened with ruinous scandal, she is forced to enter a devil's bargain with Envy. A bargain that reveals secrets and ignites passions that neither of them expects. 
 
Together, Envy and Camilla must embark on a perilous journey through the underworld - from glittering demon courts to the sultry vampire realm and beyond - while trying to avoid the most dangerous trap of all: falling in love.