You can find the first story I had my students write in preparation for our comic unit here.
Our second story fit nicely with the first (isn't it nice when that happens?) and they were to pick any fairy tale they wanted but tell that fairy tale from another characters perspective.
I started the unit off by reading them the story "Little Red Riding Hood"
THEN, if I would have been more prepared I would have read them "Honestly, Little Red Riding Hood Was Rotten!" by Trisha Speed Shaskan only we didn't have it in our school library or any library in the city (I'm pretty sure I even checked online at Chapters and they didn't have it either). So instead I found some stories online that kids wrote on it from another characters perspective (one was the wolf and the other the wood cutter I believe). They weren't the greatest but they were okay. PLUS this way we could discuss what we would change and how we thought they were a little weird.
Sidenote: one of the stories was written by a student in Australia somewhere and when I told my students they insisted that I read it with an Australian accent. I did not oblige.
Anywho, we talked about the parts of the story that didn't change even though the perspective of it did change. We discussed how in the wolf's version he was made out to be a good guy and Red Riding Hood was made out be bad.
Then I let them use the rest of the class to look through the fairy tales I had brought to class to pick a fairy tale they wanted to write on.
Sidenote: Next time I think I would make them all choose the same fairy tale OR give them the option of 3 that I'm familiar with (I'm sure I could find them online, print them, and then they could highlight the important parts that wouldn't change no matter who told the story).
Once they had picked their fairy tale I had them write out [about] 10 points of the story that would not change no matter who was telling the story (so for example in Little Red Riding Hood things that don't change is that the wolf becomes the grandma, the dialogue between Little Red and the wolf, grandma is sick, etc).
The next class we started writing our rough drafts of our fairy tales. This time they had to do 1.5 pages (or 3 sides of a page - single spaced). Some got the assignment, others definitely just rewrote the main parts of the story and didn't seem to change much (if anything).
This is why I think it would work better if you gave them 3 options or so... you could put them in groups and they could brainstorm some ideas
(look at me making my lesson better for you)
I don't recall how many days I gave them to work on their rough drafts - probably 1.5 hours or so (maybe 2) and then we did self and peer editing again (because remember it took me a while to catch on that they weren't doing a great job at this - only because most of them have a hard time handing things in).
Once again they typed out their good copies and handed them in with their rough drafts.