Reapers of the Dark by Adaline Winters

Cora Roberts—keeper of a soul-sucking alter ego, mate to the biggest shifter around, and representative of her kind in a super secret organization led by her Uncle Lucifer.
Cora and Hudson are in the middle of the mating dance, meaning he’s overbearing, obsessed, and a little unhinged. The heat is on from both of their families to tie the knot officially. However, when White Castle is suddenly overrun with an army of ghosts, Cora and the gang get sucked into another supernatural disaster. At the center of the chaos? Eloise Roberts. But to wield that kind of power, she’d need more than demons, shifters, or vampires—she’d need a deity.
As Cora battles her own dark alter ego, Hudson is hiding a secret, one that will change everything Cora believes about their bond.
With all these rival forces converging, Cora might be forgiven for missing the biggest threat she’s ever known.
So when faced with the choice between her mate or the world, which will she choose?