Hello, Neil! I've always been extremely amused that both Good Omens and Supernatural have demon characters named Crowley, and now that GO also has an angel named Metatron, I have to ask where you get your name inspiration from? I know this is most definitely a coincidence but I'm still interested.
No, it's not a coincidence: Eric Kripke was a huge Good Omens fan, and always happy to talk about it. (And a Sandman fan and an American Gods fan.) You'll find bits of each of them in Supernatural.