I have the same problem. At school kids bully me for being obsessed. I got called horrible names. No one else understands my references and people just get confused. I understand how you can only have discussions with random people on Imgflip. I get you, even if you I dont think I do... i really do. Never go into hiding, it will make you depressed and tormented. Trust me I’ve tried it just creates demons in your heart. Never let others put you down for what you love in your heart. Trust yourself and keep your head up. Harry Potter is not childish. And even if it was, it’s what you love in your heart. So no, dont go into hiding, actually, I would go out of my way to make sure they know Im a harry potter fan. It’s what I do. And I own it. You should too!
There is a song by Phillip Phillips called Raging Fire and there is a quote from it in which I believe relates to this situation. I live by it:
“Hold on to what makes you feel. Don’t let go it’s what makes you real.”
I’m like you, I get you, I’m here for you even if you dont know me.