I do that quite a lot with challenges, although I've been trying to stick with the 500-word limit recently on this one. This fic though, it was an idea that came to me Monday when I was washing the dishes, then the news challenge prompt was posted Tuesday and my fic idea seemed to fit. A bit of serendipity there, so I started expanding on the notes I'd jotted down. Sometimes plot bunnies just pop up out of nowhere...