Triumph Over Fate by Emilia Hartley

Kai wants to see Bearclaw Castle razed, but he can’t destroy the place with his sister inside.

Not that Kai is ready to forgive Mimi for leaving him alone to deal with their father, but he does still love her. He figures he should at least tell her the old man has died. He doesn’t expect to find Mimi cozying up to their family enemies, though. She’s even mated one of them!
While he’s still off balance from his sister’s betrayal, she come in. Sweet, spunky, and hurting, Stormi draws his attention in a way no one else has. If he weren’t such a monster, maybe he’d stick around and see if he could get a piece of the happiness his sister and the Carsons have found. He’s never been the settling type, though, and his ancestor’s ghost is hanging around to make sure he doesn’t change for the better.

Since her husband left her, Stormi Blackford has sworn off men, but Kai Fisher is tempting. She can’t remember the last time anyone looked at her with that kind of desire. Did her husband ever look at her that way?
Plus, Kai is just the right mix of protective and supportive. She’s beginning to wonder why Mimi thinks her brother is such a beast. Maybe it’s the influence of the ghost up at the castle. That termagant seems intent on possessing Kai—and destroying the inhabitants of Bearclaw Castle. Stormi has a gift for dealing with ghosts, though, and she doesn’t intend to let this one have her vindictive way, no matter how powerful she is.