Alan Moore created the comic book character of John Constantine, later adapted into a film that starred Keanu Reeves playing the character, but Alan Moore may well have come face to face with his ceration before then. In his words:
“One interesting anecdote that I should point out is that one day, I was in Westminster in London – this was after we had introduced the character – and I was sitting in a sandwich bar. All of a sudden, up the stairs came John Constantine. He was wearing the trenchcoat, a short cut – he looked – no, he didn’t even look exactly like Sting. He looked exactly like John Constantine. He looked at me, stared me straight in the eyes, and then just walked off around the corner to the other part of the snack bar. I sat there and thought, should I go around that corner and see if he really is there, or should I just eat my sandwich and leave? I opted for the latter; I thought it was the safest. I’m not making any claims to anything. I’m just saying that it happened. Strange little story.”
In the snakes & ladders book a fictionalised version added he once came up to say “I will tell you the ultimate secret of magic. Any c*** could do it.”
Now either Alan Moore was telling another good tale, delusional, had subconsciously made him and had seen the guy before or possibly he had brought Constantine into existence. This has been discussed before as something called the Tulpa effect, essentially this is a Buddhist belief that a thing or being can be willed into existence with the right spiritual and mental discipline. The concentration and the power of the mind is what creates it but with enough vitality the creation can free itself from its maker. Perhaps we shouldn’t be so quick to dismiss Alan Moore’s story, or come to think of it, a child with an imaginary friend….