On Sex with Demons. With demon sperm trending in the news, Medievalist Dr. Eleanor Janega takes a brief look back at the rich medieval history of horny devils: “See the devil can’t make his own semen, being as he is incapable of making life, so in order to get his hands on fresh come, he transforms himself into a succubus, has sex with a dude, nabs the semen from said dude, then transforms himself into an incubus, shags a witch and injects the stolen jizz in order to knock her up.”