Silver Fairy Tales

People assume that that's where demons and monsters came from - as a way to scare children off from behaving badly. And the really big demons were then used for adults with the same purpose. The Silver Fairy Tales is probably the most renown collection of such stories. There are 24 in total and the book is named by its silver-like shiny embellishments on the cover. It's deemed by many as a classic.
The most popular educative story is the one about a demon stealing your words you say during the night, trying to make children go to sleep and be quiet, for once, so that the adults can get some rest too. So once upon a time, in a nameless village, a demon appeared, shaped like a dark cloud, with the ability to steal your speech if you are not careful enough. It is usually called the Whispering Shadow, although the names can vary region to region and can creep into your bedroom through an open window or a door or through some kind of a crack. Whatever it hears, it can steal for itself, being able to use the voice of the child and impersonate them perfectly. After it steals a couple of words form you it will start to ask you some questions, trying to feed from you more, whispering into your ear, its voice is said to sound like hundreds of rasping, quiet voices mushed together, believed to be the echoes of those he stole from before. The more it hears the stronger it becomes, eventually stealing the entire gift of speech from its owner, like it did many times before. Needless to say, the story doesn't end happily.
Apart from trying to keep children quiet, there is one other message that all the 24 stories have in common: demons do not care about anything, they just want to eat you. The end.