In Supernatural, around when the protagonists meet Chuck, they believe he is a prophet of the Lord, and this conversation can be heard:
Castiel: You must understand why I can't intercede. Prophets are very special, they're protected.
Dean Winchester: I get that.
Castiel: If anything threatens a prophet, anything at all, an archangel will appear to destroy that threat. Archangels are fierce, they're absolute, they're heaven's most terrifying weapon.
Dean Winchester: And these archangels, they're tied to prophets?
Dean Winchester: So if a prophet was in the same room as a demon...?
Castiel: Then the most fearsome wrath of heaven would rain down on that demon.
But in season 8 episode 7, Crowley can be seen torturing Kevin, a true prophet of the lord. What happened to the most fearsome wrath of heaven raining down on Crowley?