Whether you like the Disnified Happily Ever After versions or the grim Grimm originals, fairy stories are a great source of inspiration for a writer.
You can rewrite the tales with a modern twist, or a funny one, or you can simply take the morality-play form and use it for your own story.
I come back to this prompt idea again and again because it is such fertile ground and because EVERYONE knows a fairy story or folk tale (if you need a reminder of some, go here).
Alternatively, you could choose to write an allegory (think: Narnia, or Animal Farm). If you do write an allegorical story, however, bear in mind this advice from James Scott Bell’s book Plot & Structure
“Allegory is difficult to do well, since it may just come off as merely preaching in the guise of an imaginative tale…Make the characters real and not just stand-ins for your ideas.”
Rewrite a fairytale/folk story or Get Allegorical
Go!
From yesterday: What would have happened if the glass slipper broke before Cinderella tried it on? How could she prove that she was the girl at the ball? Is there a Medieval Law School that she can attend to defend her case against the evil step sisters? This has always troubled me. I mean, they are traveling around with a very delicate piece of footwear on a pillow. A pillow! Is that considered safe? Poor Cinderella, Or should I say Lucky Cinderella? Thanks to a level headed foot man, good old Cindy got to try on the glass slipper. Think about it, she could have lost it.