When I was about 5 I believed I was a panther in human form. And I had a magical blanket that could transform me while I slept. Some people say good imagination. Other times I know I really believed this. But, then as a younger kid I felt I wasn't human, either. An alien or something magical. I believed this for a long time.
The first "paranoid" thing for me was when I was 8 years old I believed my class had installed closed circuit security cameras in my bathroom at home, and they would gather a club house and watch me go to the bathroom or take a bath so they could make fun of me.

I used to hate going to the bathroom and would hurry and often cover up with towels.