Yeah, you'll probably get teased a lot as a teenager because everyone's out to be a little prick to anyone who looks remotely childish and weak. Your best bet is to just keep your head down and don't feed them metaphorical fuel to shoot back at you. As bland as that advice is, if they don't know, they won't tease you. Yes, I'm advising you to go into the closet, but people like these can't be convinced that your fandoms aren't so bad or that you're not immature for liking it. You could try to defend your right to like it. In fact, if you do, that's thumbs up to you. I've just felt like it never really worked when I was a teenager who got made fun of in high school for my fandoms. *shrug*
After I graduated and moved on to college, it's gotten immensely easier. I don't get teased nowadays, and I'm open about it. It's probably because when you're at my age, everything about your childhood suddenly seems awesome, probably because you're thinking, "In four years, I have to suffer through the real world and start paying my own bills! OH NO!"
So, instead of getting teased, I get, "Awesome. I think I'll join you here, Jax. Let's write smut together!"
In other words, hang in there. Speaking as someone who was there at one point, it gets better after a few years.