The Butcher and the Ballerina by Kris K. Haines

Love is the deadliest performance.
Ronin Matakos, the Butcher of Aethalia, was once a great war hero.

He was once a lot of things—revered, respected, worshipped. But ever since the Empire caged his wolf, he’s suffocated beneath his tarnished reputation, wandering through an aimless fog of fights, females, and that most intoxicating of substances, Delirium.
So, when the Empire comes calling again, this time with an opportunity to regain everything he’s lost, the offer is too good to pass up.
Too bad it’s an assignment to pose as the lover of the one female in Ethyrios who’s immune to his cocky charm.
Mireille Valette is at the top of her game. Both her games, really—prima ballerina and spy-assassin for the Empire. And this lone wolf, whether on stage or on a case, certainly doesn’t need a High-Gods-damned partner. Especially not one as lazy, entitled, and arrogant as the Butcher.
The pair are pitched into a deadly game of cat and mouse with an eccentric Fae billionaire, one with plenty of secrets buried in his macabre mountain estate, the Cathedral of Bones. In this sinister world of bizarre rituals and forbidden magic, danger lurks behind every posh, polite smile.
And just when Ronin and Mireille’s fake relationship starts to feel all too real, the secrets of their own tortured pasts rise up to haunt them.
Will they survive the Cathedral of Bones? Or will love be their final performance?