I investigated some things with the tags here. Not counting duplicate tags, Firefly has the highest Derpibooru image count of any character who does not have a tag on FimFic, however, Firefly is a G1 pony and is subsequently disqualified. That record instead goes to Shoeshine aka Linky. 5 characters
I think it's ready, at least. Expect it soon. Somewhere between 1,201 and 2,010 words, despite being a quick oneshot it's taken me literally forever... I guess I need to work on my writing skills and confidence...