Delusions that I had I my childhood and before severe psychological highs and lows:
Delusion that no one has facial expressions until I was 16 years old
Delusion that I murdered a 5 year old child when I was 4 years old, and once sexually touched a 10 years old girl when I was seven years old.
Delusion after severe psychological highs and lows:
Delusion that corrupted CIA, MP and SWAT were following me everywhere I went, and that there was police brutality all over the world.
Delusion that I was working for the military to find aliens (Once committed a battery assault when I had those delusions, no charges were filed against me)
Delusion that I sometimes download CP for five years until age 20.
Most of those delusions that I had were non-bizzare.
I had a delusion that I needed to defend myself, and was arguing with my former highschool teachers to let me go, and acted violence, because I was scared. I was suspended from school for a year until my severe delusions and manic episode tuned down.
When I examined my own delusions in retrospective, it turned out that every little thing that happened to me in my childhood, from the kinds of cartoons I watched, to the church I went to, and what girls said around me, impacted the content and manner of my delusions significantly. My childhood experiences shaped my delusions basically.
My delusions and hallucinations started in my early twenties. As I child I was mostly normal.
I suggest you try to find the roots and reasons and inspirations of your delusions in your past. This may improve your ability to stay grounded.