12. Have you ever attempted an "adaptation" fic of a favorite book or movie but set in a different fandom?
If I remember correctly, I had such an idea, but I can't remember what it was. The biggest problem with this for me is that whatever I write has to fit into canon, because I'm just obsessive about that kind of thing, and it would be difficult to smoosh another work into a crack in the DW universe.
One thing I plan to do sometime is "fix" a couple of canon stories. The one I really want to rewrite is "Black Orchid." It's one of my favorite episodes, simply because it is so different from every other Doctor Who episode and it lets you see a glimpse of the TARDIS crew living normally, rather than running from the threat of the week. The problem with it is that its main plot (the murder mystery) is poorly written. I would love to take that episode and make it a true murder mystery with the Fifth Doctor, without the reveal of the murderer in the first few minutes of the show and with the possibility of one of the companions being the murderer. If I ever do it, I plan to replace Adric with Turlough, because he's a far better companion for this story. The other appeal of this idea is that I'm going to try to write a murder mystery. I really don't see how to do it, but it should be fun, if I ever get around to it.
One common type of adaptation fic I see is the "characters adapted and set into another setting." It seems to be done a lot with the Tenth Doctor and Rose, e.g. "Rose Tyler is the younger daughter of a gentleman living in Basingstoke in 1825. What happens when John Smith, a handsome surgeon from London, moves into the empty manor house down the road and sweeps her off her feet?" These types don't interest me per se, since the show is compelling to me not only because of the characters but also the setting and the backstory. The Doctor is fascinating not only because of the episodes I'm watching now, but because of his whole history, from his academy days, through fleeing Gallifrey, defending the Web of Time, fighting in the Time War, and firing the Moment, to his more modern adventures. Putting the characters into another setting which doesn't include all that is, in my mind, pretty pointless.
On the other hand, some of the characters are compelling in themselves and would be fun to use in other settings. If I did do so, I wouldn't make it related to Doctor Who in any way. I would instead create new characters with similar personalities and backgrounds to use. I guess that would make it an original fiction. Part of it is that if you're going to put these characters into a new setting and history, you have to go through the work of explaining how they fit into that setting and why they do what they do - you don't have the DW backstory to rely on. If you're going to make the effort to do all that, why make it fanfic at all? Adapt the characters completely and make it your own original work. Heck, isn't that how Twilight started?