Raw Ignition by P.C. Stevens

The Dark God has disappeared, but for how long?

As Pirmas leaders cautiously await Mrakzlo’s re-emergence, demons have expanded their recruitment efforts via a recreational tonic. Their target: fire fae.
And unbeknownst to the Darkness and its creatures, a slave and a warrior are about to rattle their world.
While taking advantage of a rare escape opportunity, Pierce—a fire fae and his queen’s favorite sex slave—meets a lady warlock he’s powerless to resist.
Naomi is a Blood Lord—a warlock of royal rank who hunts demons to collect their blood for warlock consumption. While on duty in Underworld, she runs into Pierce, a delectable stranger who stirs feelings and needs she thought long dead.
A clash of uncanny circumstances throws them into each other’s arms. Following a passionate encounter, she helps him successfully escape and they part ways. Saying goodbye should be easy. Yet Naomi persistently haunts Pierce’s thoughts, and she can’t stop desiring him, yearning for him…
Pierce’s newfound freedom doesn’t last long. But it’s not his master who comes for him.
“You’re changing,” his captor alleges as he dumps Pierce in a cell somewhere beneath Underworld’s wilderness.
Changing… into what?
Naomi soon discovers exactly what. To her horror, she learns she might’ve set a monster loose into the world. She must find him, because duty demands it. Not because she aches to see him again. No, not because of that…