Okay, now this looks like fun....
Comment with a story I've written, and I will tell you one thing I knew, learned, or wondered about while writing the story that didn't make it onto the page.
And/or, as a bonus:
Give me one of my own stories, and a timestamp sometime in the future after the end of the story, or sometime in the past before the story started, and I'll write you at least a hundred words of what happened then, whether it's five minutes before the story started or ten years in the future.
All my stories can be found:
on my journal, tagged as fanfic or
on my FF.net account