The Stolen Bride (Baldwin Brides #5)
Susan Spencer Paul

Though the dark raged within him, Mistress Sofia was his light. She alone made Kayne feel something of grace and innocence, blurring memories of war and bloodshed that haunted the depths of his being. But the bliss found under a summer moon could ne'er last forever, for keeping his beloved safe would mean a return to the heart of darkness that lay within him.