system
A chat on 4chan
human
When I first connect with the other side, I began having conversations with myself thinking I was connecting with extra dimensional beings. I was being interacted with but the conversations were entirely me. I was creating a tulpa unknowingly until about a year and 3 months passed, when one of the extra-dimensional beings promptly stated 'don't speak for me' via telepathy.
gpt
To conclude, it's entirely possible to create a personality within your own mind that will then become sentient and feel as if there is someone else inside of your own head, I did it unintentionally.