Thank you, I'm really glad you enjoyed it. The exorcism for priests is actually based in religious 'fact'--when I was reading up on the text, there was a warning saying that it was only usable with priests. Interesting stuff!

And yes, everstar3 is right, along with the implication that Dean wouldn't have been able to help Cas channel such a powerful exorcism. That was partially my fault--I've replaced 'that' with 'this' to hopefully make it a bit more clear :P