When I was 7, I used to believe that Misty and Brock (both from Pokemon--I used to love Pokemon) were always with me, and that I was really Ash, I just hadn't realized it yet. They would always try to convice me that I wasn't Audrey, I was Ash. But I never believed them.
They would also help me take tests at school (don't know where I came up with that). When I did bad on a test, I went home, locked myself in my room, and screamed at them until I lost my voice, because I thought it was their fault.
I believed all of this up until I was 13 (I'm 15 now).
A childhood belief about imaginary friends

others believed things like this
- I used to believe the the tooth fairy was a Pokemon fan because she got me Pokemon Crystal for my lost tooth— Pokemon fan
- i didn't beleive this, but a kid my sister knew thought if he screamed in a really high voice, he ran faster.Anon
- I used to beleive when ppl didn't talk (deaf ppl) they lost their voice and could never talk again!— Tiara 10
- I always believed that my dad went to school with Billy Bunter. I think my brother believed it too!— Karen
- I thought the cremations were for people that wanted their love ones buried at home.— Helen
- I believed that I had a fake right big toe, having lost my real one in the plug holder (thanks Helen!)— Mike