Well for whatever it is worth I tend to get extremely similar delusions, either that I am a demon or that I have one attached to me. I also grew up in a rather extremist religious environment so I imagine that a lot of it is inspired by that. Basically my mental illness combines with my childhood experiences, and then that is what pops out. Delusions about being a demon or having one attached to me.

I have even had many, as in like countless, nights over the years where I have pondered it deeply for hours. I even come to the conclusion of feeling sympathy for the demon that I believe is attached to me. It can never be redeemed, it was cast down and damned for one rebellion, something humans do all the time but can get forgiveness for. What motivation does it have to redeem itself, if it can uh, never be redeemed. I imagine it to be a lonely, tormented thing, as miserable and crazy as I am. Sometimes it feels like the only consistent friend I ever have.

But if someone asked me if I believe in demons, I'd look them in the eye and say, "No." And I don't. I don't believe it is real. But it's real to me. And I can simultaneously experience it as real while knowing that it's not. If that makes an ounce of sense.