He had always known something had been watching him like a guardian angel of some kind, It was only confirmed when Castiel had told him he had a guardian angel.

He's been studying on it, sleepless nights just to figure out who this angelic being was ever since Cas gave him the name.

It wasn't until he and his brother were on a hunt and they had been separated, he found himself in an old temple/church with three statues of angels, the one in the middle looked fermilier and he didn't know why.