Once in a Blue Moon by Delilah Devlin

In Jefferson Parish, deep in the bayou, is a place called Bonne Nuit. Off the beaten path, isolated by swamp and connected to the sea, there the Beaux Rêve Coven thrives. Five witches… Too many demons to count…
Bryn Cavanaugh and her coven like that the community they live in is isolated thanks to a storm that destroyed the bridge between them and the outside world. Now the state wants the bridge rebuilt. When the construction crew checks into the inn, Bryn begins to suspect something about the crew’s boss isn’t quite…human.
Bridges are Ethan Thorne’s thing–after all, he’s a troll–so building a simple span over a remote canal in backwater Louisiana shouldn’t be this much of a problem. When he follows the pretty little innkeeper to a midnight rendezvous, he discovers why his crew keeps running in to trouble. Bryn and her coven are casting spells in the moonlight.
As a troll, Ethan feels the sting of his low place in demon hierarchy. But finding an unprotected coven of witches in the middle of the bayou could lead to all sorts of adventure. And it’s better to keep your enemies close…