The Universe's Mixer

Castiel took Dean’s suggestion of reconnaissance very seriously. Though demons could not track angels instinctively or vise versa, and Castiel was not afforded the senses that would reveal any of his brethren to him, he looked in what might be termed ‘the old fashioned way’--that is, by looking. That meant a lot of traveling through the City, staring at people and making them nervous, watching day-to-day activities and noting the patternless shifting of the Cityscape. It was truly one of God’s more bizarre creations. Since not even an archangel could create a reality that would fool Castiel, he was increasingly certain that his presence here was God’s Will.

( This reassured him somewhat. )