You're never too grown up to play make believe and I think the world would be a much better place if adults (and adolescents who are eager to leave childhood behind) just accepted this, because the way they cope is unhealthy. Everyone plays make believe. It's part of being human, but something shames us out of it. Something tells us that we're too grown to bother with imagination and roleplay.
To cite an example, do you remember when there was a huge surge of people faking dissociative identity disorder? Most of the people doing that were either adults or adolescents at a stage in their life when they're trying to shed the hallmarks of childhood. They made fools of themselves, sure. But despite the social risks it still somehow feels more safe and socially acceptable to lie about having a rare and poorly understood mental disorder than to simply tell people that you want to talk about your original characters. It's almost like people feel that there's more shame in admitting that they are imaginative and want to play with their imaginary characters, than there is in lying about a psychiatric condition. As though having OCs and daydreams is more stigmatized than dishonesty and destructive misinformation about mental conditions.
And that's just the Tumblr-ish variety. I have seen so many grown men completely go out on LARPing as "modern vikings", doing anything and everything but admit that they're LARPing. People might make fun of you for saying you're a modern-day viking, but playing as your make-believe warrior character and playing dress up as a middle-aged man is treated a hundred times worse. So they'll endure the mockery, because they're convinced that the alternative is so bad that they'd prefer to pretend their make believe play is anything but what it actually is.
I'll sometimes see people launder their own imaginations, sometimes claiming that a scenario they imagined came to them in a dream. Why? Because it feels safter to share a story involuntarily placed into your mind than it is to admit that you just wanted to share your daydream with someone.
I think we need to make people feel safe playing with make-believe characters. It's healthy, it's normal, and god knows there's already enough stigma out there doing everything it can to crush the imagination out of people. People shield themselves from that stigma with dishonesty and even self-imposed delusion, and I'm tired of it. Be free. Tell stories, play games. Even people in ancient times LARPed and told stories and played as characters, and they aren't so different from us. I don't know when or why we started gatekeeping imagination as being limited to either child's play or a vocation for a small number of professional creatives, but it doesn't have to be that way.
So go ahead, tell me about your OC. Tell me about your daydream. Tell me you want to play grown-up make believe. I want to hear about your characters.