Author!Anon. As far as I can tell it's a fan theory - I've only seen the show, so I don't know about the book, but I don't remember it either. I incorporated it here because there was a prompt in Round One and I really liked the idea, and it seemed to fit well with Grant, so I put it in. I didn't actually intend to originally, but the scene where the barghest attacks Childermass sort accidentally laid a pretty nice framework, and why not? Heh. I'm glad it worked for you!