That makes sense. I've always thought of Dean having green or hazel eyes, while Sam had brown or dark green. That's actually.... Would you mind if I borrowed that for my own HP/SPN story? The whole 'people with green eyes being given huge tasks'? I was going to go with the 'messenger of the gods' theory myself, but it would be awesome to blend those two theories into one now that I think about it.

Perhaps Harry gets captured by demons and Castiel steps in and saves him with the Winchesters? Is this before or after Alastair bites the dust? I can't remember which episode that was in. Can't wait to see where you're going with this story.