Castiel didn't want to move. Dean's request about the strange demon had moved to the back of his mind. Every time a thought drifted across his consciousness, he was able to dismiss his various duties without a great deal of effort. The war was not on-going here, not yet. Dean was safe, or surely he'd know. The City was secure from the inside, and something would likely break on that informational front--that, or Fred would find out the solution. Castiel had great faith in Fred and an almost startling respect for her intelligence, considering that she was human.
Castiel glanced with some interest at the titles of the books she held. "Possibly. Probably not by name, if so. I am a Watcher, not a Messenger. Well. Not usually." Then, solidly, he said, "I come from Heaven." He seemed to think this would be a great help.