Sleeping With the Devil: Medieval Illuminations of Demonic Sex
In early Arthurian legend, Merlin was the product of a conception between a demon and a virtuous sleeping woman. This idea was apparently popular, as it made its way into a lot of medieval art. The devil could be blamed...
https://www.neatorama.com/2020/03/08/Sleeping-With-the-Devil-Medieval-Illuminations-of-Demonic-Sex/