system
A chat on 4chan
human
I had recurring dreams as a child of people not being who they are, like for an example I'd be at home with my mother except I knew it wasn't my mother, just someone evil wearing her skin. Or I'd hear her voice calling me and be afraid to go, because I knew it wasn't really her

This was over a decade before skinwalker stories in 4chan and I had never heard of anything similar, so I guess my child brain just came up with the concept on it's own. Or maybe it's a common, primal fear of some kind
gpt
I remember having those imposter dreams alot. Happened only about people I was close to.