"The chick’s eyes were illuminating the alley and she had friggin' horns. And her teeth…she had fangs like a snake. His shout was more shock than pain, though there was certainly that. And outrage. And an edge of hysteria. Under normal conditions, Dean Winchester did not do hysterics, but when an honest-to-god sex demon came a hand’s breadth from biting off his most precious possession, he figured he was entitled."
A plotty succubus-made-them-do-it fic, with a twist.