The Start of Something Good

In a complete AU, Castiel was sent to watch over the newly-born Dean Winchester, who would some day grow up to be the Righteous Man. For now, he was simply the Righteous Baby. But not all goes to Divine Plan (or does it?) when the demons, a certain Trickster Archangel, and others get involved. This could either be the start of something good, or complete and utter chaos on Earth.