I don't really know what kind of reputation I have, but in high school, a lot of people thought I was just an unstable mess. They probably also knew me as a poser, because I desperately wanted to fit in and I would pretend I wasn't autistic (though I'm sure everybody saw right through that) and that I liked things I actually couldn't stand.
Now, I'm trying to not try as hard (if that makes any sense) and I am no longer ashamed of who I really am. I'm autistic, I'm obsessed with Science Fiction and the UK, and I'm okay with that. I want people to know that this is the real me and that I'm not the same person I used to be, but I think it just takes time to change people's minds and for people to understand that people change and grow. One needs to have positive experiences with those people and eventually, they will likely see the real you and not associate you with the bad experiences. High school wasn't that long ago for me, but I have grown a lot, I think and I wish that more people knew that, but it doesn't really matter what they think in the long run. The people who really know me know I have changed (hopefully for the better) and that I'm happier living without having to constantly pretend to be somebody I'm not.
It might take a little time, sadly, but it is worth it. Good luck 
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"Have you never seen something so mad, so extraordinary... That just for one second, you think that there might be more out there?" -Gwen Cooper, Torchwood