Popular images of Mahomet hardened into fixed fictional characters
Evidence
At the level of popular poetry, the picture of Mahomet and his Saracens changed very little from generation to generation. Like well-loved characters of fiction, they were expected to display certain characteristics, and authors faithfully reproduced them for hundreds of years. It would be hard to say when these characters came to be recognized as mere figments with which to frighten naughty children; but this was certainly not their original status. — R. W. Southern, Western Views of Islam in the Middle…, 168