But possible. It probably wouldn't be a standard mission, though; I imagine the agent(s) would get a specific debriefing from the Flower and told exactly what they could and could not do.

I don't truly know; I've heard of the whole "fic of a pre-existing fic" concept, but:
It seems to me that this kind of fanfic is not as wholly based on the true canon as its predecessor would have been.

Fanfic 1 is directly based on canon, with the author's own ideas added in. Fanfic 2 is based on the first author's ideas, before the normal canon, rather than an original idea.

Of course, if the first fic was perfect, well-written, well-thought-out, and canon-adherent, while the second fic is a disgrace to not only the fandom but to the first author's work, there would be due cause, especially if the first author is outraged.

I suppose it could work, but I would definitely acknowledge the author of the fic it's based on, as well as the author who originally created the fandom, in the disclaimer.

And I might even ask the first author's permission, because you never know; they might have let a not-as-talented friend write something based on their story, and if they discover you've gruesomely killed it they might get mad.

the original fanfic would have been using the world of an esablished canon- that's what fanfic *does*. Therefore, a fanfic of the fanfic should still be in that same world.

E.g. a really good fic set in the Tolkienverse is still IN the 'verse. So fanfic of that fic would also be set in the Tolkienverse (unless they've done something really screwy, in which case they should be cleared out anyway.)

So basically, a fic of a fic would probably be violating the original canon, not the fic canon. If they're using the same characters, it'd probably be counted as a very bad copy of the fic, not a secondary fic, and would be screwing up the Canon world. It could also be nabbed for plagarism.