There's an image that was making the rounds through social media a while back after it appeared on an amusing clickbait list of startling things from medieval manuscripts. It is a depiction, found in an illuminated life of Alexander the Great, that appears to show a woman lying in bed with a dragon, while a crowned man stares at them through a hole in the door.
And that's precisely what it is. To the audience at the time, the story was so well-known they would have recognized, at a glance, that the man is King Philip of Macedon, watching the conception of his son Alexander.
Alexander the Great was one of the most popular figures from the medieval Matter of Rome - the retelling of classical stories, often in a then-contemporary setting. By the third century, a Greek manuscript falsely attributed to Alexander's court historian Calisthenes had appeared which spelled out a somewhat mythologized version of the king's life, and this became the basis for many later accounts. One such version, the Alexandreis (a Latin text from the 12th century) was even directly translated to Icelandic under the title Alexanders saga. The first known epic poem, on the model of the French chansons de geste, in German is the Alexanderlied, also 12th century. The Quranic figure Dul-Qarnayn is also thought to be a mythologized version of Alexander the Great.
As for that image with the dragon? The earlier texts call it a snake, but a legend that appears in many medieval Alexander texts is that King Philip looked on, through a window, while his wife was impregnated by a dragon or serpent.