Highland Beast by Heather McCollum

Bàs Sinclair is the cold and brutal hand—and sword—of justice across the Highlands. He has one destiny: to bring fear into the hearts of guilty men. But when he is called to execute a midwife for her crimes, he cannot raise his weapon. For Bàs already knows this lovely, part-wild creature. After all, she gave him his first and only kiss…
Shana Drummond will do anything to protect her beloved sister. Now her cruel, merciless brother-in-law has called upon Bàs to have Shana killed for crimes she didn’t commit. She can’t reconcile the cold, lethal warrior before her with the gentle one she met—nay, kissed—only days before.
But mercy from Bàs can only lead to one thing: war among the clans. A war that will test allegiances, tear families apart, and challenge everything Bàs knows about himself and his heart. Because once this Highlander knows love, nothing will stop him from keeping Shana safe…even if it means destroying his own destiny.