What do you find to be the most intriguing mental disorder/ syndrome/ delusion?

The Fregoli Delusion is pretty weird. It's where people believe that different people they know are all just one person.

I suffered from a delusion as a small child...but never since. When I was like 5 or 6, I thought that the people in my life (family, mom, dad etc.) were not actually real people. I thought that they were only "real" when they were in my sight or field of vision. Otherwise, they were like robots or something that only came to life when they were in my field of vision. Of course I was never able to see them in their dormant states, although I often tried to "catch" them by sneaking into a room etc., hoping to see them deactivated. Never worked lol.

I have not been able to find any info on this type of thing. I grew out of it at some point.

Multiple personality disorder, or Werner syndrome (when children are born looking really old)

Sociopathy or psychopathy.

There's just something about people who can really manipulate that is intriguing.