Cas met Steve's eye, knowing it was likely a shocking revelation. If one did not believe in angels to begin with, this talk was somewhat easier, but for a believer, it was evidently uncomfortable. Such a realization had been difficult for Cas himself, though his had been somewhat forced due to the urgency of events.
"Perhaps not you," he conceded. "Unless they sensed something I cannot, they're far more inclined to attack Anna or myself, though I will tell you now that standing in the way of their agenda will classify you as an enemy. They are very methodical...and if you suspect they do not have an agenda, think again."
Unfortunately Cas knew this from experience, though he still firmly believed that he had only been following orders at the time. Long before he'd learned he was not receiving God's orders, he had been no better than Zachariah or Raphael. And neither of them were what one would wish to aspire to be. "Thankfully, there is no Apocalypse here for them to be in favour of, but that is not to say they would not try to start one. They are unpredictable at best. I've...fought them several times. Even after the Apocalypse was prevented."
He had no desire for Steve to be unprepared in any situation, so it only seemed to make sense to tell him as much as he knew. He felt the favour would be returned, were they facing enemies from Steve's own reality, but thus far, Cas had only encountered those from his own and from Buffy's. "That...is somewhat complicated," he conceded. "There is only one technique that can expel an angel from its vessel and only one demon that I am aware of knew it. However, there is the matter of banishing sigils, though the process of making one is somewhat painful. For now, I feel we should stick to vampires and shapeshifters."