What's the longest time you've been in a fandom. Not necessarily your oldest fandom, but a fandom that you started and still continue to read/write/create content for in some way.
Honestly, it would probably have to be Harry Potter. I got into it during high school, started from seeing the first movie that had just came out to buy/rent and I hadn't known anything about the books until then, but once seeing the first movie I was curious and ended up reading the books and it just bloomed from there. From reading the books to going online and finding the fandom to being excited about the movies coming out, Harry Potter was honestly one of the biggest fandoms I joined and the longest I've ever been in fandom for. Even now, while I've gone and gotten myself into other fandoms along the way and despite everything that has been revealed about the author over the years especially recently, I'm still kind of in the HP fandom. It was a massive influential factor in my life, in more ways than one, and I'm still a part of it. I still read fanfic, I love a lot of the fanart and the gifsets and discussions that come from the fandom still.
What's a fandom that you wish had a bigger following?
The Expanse. I know the show has gained more attention over the last couple of years thanks to the fan campaign to save the show and getting more people to notice and start watching it, but I do wish there was a bigger online fandom presence. Unfortunately, this is what happens when it comes to science fiction shows that aren't Star Wars or Star Trek related, they tend to be very niche and very much under the radar. Someone pointed out that it probably won't be until after the show ends that people will finally end up hopping onto it and going, "omg why didn't anyone tell me about this show??" Which, y'know, fair enough, better late than never and I've done the same thing with shows that I've gotten into that people told me about that ended some while ago. But still, I do wish there was more fan engagement.