Despite its loud success, “The Merciful Ones” should be considered within genre literature—somewhere between Anne Rice and Tom Holland. Of course, Lord Byron and his doctor Polidori here are not quite vampires, but rather victims. And the entire book is the embodiment of the metaphor “Creativity is a reward for serving the Devil.” Andahaziev’s half-beast half-human—an ugly appendage of a beautiful pair of twins, living off erotic visions of men—is no better than the hybrid of Holland’s Byrom and Dracula. Byron, Shelley, Mary Shelley, her half-sister Claire, and Dr. Polidori arrive at Byron’s castle on the shore of Lake Geneva. The climax is the night the “Vampire” and the “Frankenstein” are created…