Writing Backward

Yesterday I wrote about Alexia's Pen and YA and MG. I ended by saying that I was going to make the story darker.

By adding a curse.

Here's the new query letter for Alexia's Pen:


Fifteen-year-old aspiring novelist Alexia loves the colorful pen the mysterious Arthus, a recent transfer student, gives to her. The pen is special – anything it writes comes true. When the pen writes of its own accord about a mystical Land of Imagining, Alexia learns she's not just an ordinary girl, she's an All-Knower. So is Arthus, and her mother.
The rest of the magical All-Knowers are in terrible danger. The Head Demon seeks to enslave and kill them, determined to rule the Land of Imagining. Alexia is able to control the All-Knowers with her pen, but the power comes at a cost – each time she writes with the pen, an All-Knower becomes a demon. After the Head Demon kidnaps her family, Alexia must find a way to go to the Land of Imagining. She will do anything, even if it means giving up her power, to save her family and her people and to prevent the Land of Imagining from becoming the Land of Terror.
So now the query letter is finished. I just need to go back and revise the story so that the story reflects the query. Talk about writing backward! :) I think the curse definitely makes the story darker and more YA in tone.
Have you ever written backward before?