Ace of Spades: Royal Angels by Jessica Lynch

Samael is not what anyone expects. Least of all himself…
Because Sam is a rarity among fallen angels — he’s a self-professed guardian angel with a taste for death. Back before he and his brothers fell, he was considered an angel of death who ferried souls to Heaven and Hell. Now that he’s been trapped in Purgatory for millennia, he lost the title, but not the instincts.
Determined to prove that he’s moved on from his old life to his new one as one of the owners of the hottest faction-owned casino in Las Vegas, Sam has relied on his snow-white wings to rehab his image. He’s no longer an angel of death but, instead, a guardian angel who does good deeds for the hell of it — all while Raze cashes in on the favors in the name of the angel princes of Sin City.
And then he meets Polly and, for the first time in a long, long time, Sam doesn’t just play the part to spite the Heavenly Father. He actually wants to save her — especially since he met the adorable human while she was attempting to steal from House of Sin, their infamous casino.
She almost pulled it off, too, which would’ve been enough to catch Sam’s attention. Then there’s the undeniable fact that he instantly recognized her as his fated soulmate before she cheekily made her escape.
But there’s no escaping Death when he’s got his sights set on you…
When Raze and his new mate get a lead on where to find their missing talisman, Sam makes Polly an offer she can’t refuse. Ten grand if she can retrieve the key for him, twenty if she lets him tag along on the mission. And while Polly might be a human, she’d been around the factions long enough to know that having a guardian angel at her back couldn’t hurt.
Especially one as irresistible as Sam…