Embrace the Abyss's Caress

Fiends with a bizarre appearance who have their whole body covered in a black film, and one of the races of monsters belonging to the abyss. They serve someone, act in accordance with their master's will, and lurk in dark places such as underground or in caves. Their behavior is eccentric, they are poor at expressing emotion, and it's difficult to read their intentions from their expression. If a human strikes their fancy, they'll soar through the sky and carry him where he wants to go. They can coat the man's body in the mucus secreted by their own body which induces pleasure. Once the mucus has completely permeated a man's body through intercourse, his nature changes, and he becomes a fitting husband for them. The husband can then secrete and control mucus just as they do and dissolve the film covering their body by touching it.