I never really wrote proper ST fanfic... but when I was a young teenager I wrote a lot of TV screen plays and plots and would act out whole long sagas with Spock and various non-human lifeforms. I still have some of them written down. The only story I remember doing, probably in high school, was this DS9 one with a new crewmember who was a sentient plant and gets to be friends with Odo. I have that one as a text file somewhere. But it's funny, I had no idea fanfic existed until around 2000, when I got to poking around in the VampChron stuff.