Hellfire - The Brimstone War Novels, #1

You can run from your past. You can hide from yourself. You can make a fresh start. But sooner or later, it'll all catch up with you. Willamena is a millennias-old succubus, the last of the Lilin, and daughter of the king of Hell. Once imprisoned by her lover with the rest of the succubi, she has escaped to live among the humans as Billie the Bartender. She hides in plain sight, denying her lust-filled hunger and the burning hellfire inside her, in Las Vegas.
The ambient energy there keeps her satisfied, but every once in a while, she has to feed. She must succumb to her needs and refill her power, but she struggles to take without killing. She's hunted by the incubi, who are led by her former lover. She's hunted by the Cherubim, a warrior sect of angels who would see all demons dead. When her past catches up with her, Billie has to choose to flee and save herself or stay and fight to finally see the war between angels and demons finished.
But if she fails, she'll lose her life, her lovers, and her best friend. In this high-stakes erotic urban fantasy, Leila Bryce Sin brings her fans to steamy Las Vegas, where night never ends and you can be anyone you want to be.