I had a couple classmates that pretended to be vampires back in elementary and middle school. They’d pretend their Koolaid was blood, complain about the sunlight, and bite their friends a lot. Not enough to draw blood, though. I haven’t kept up with most of them, but one guy is a teacher now. He seems pretty normal.
All the right winger panicked about “children identifying as cats” need to read this thread and remember that kids have always imagined weird things.
Also I knew one who was like that about being a horse.