Just a comment in return to your challenge for the shortest fanfic....

     there is a subgenre of the short story that I have heard of that is
simply the 250 word story.  The rules are simple:  One must tell a complete
story (plot, characters that sort of thing, not must a vignette.) in EXACTLY
250 words.  I tried it once, and even after I threw out everything I thought
I could, I ended up with a 500 word story.  So then I started rewriting it,
and it is still growing. It is an interesting exercise, and can really make
you focus on what your bare minimum essentials of any given story.  But
usually not what I would call satisfying reading.

                           -Mike Taub