[OOC: Hey, no worries! I have the same problem with Season 4 myself :) It's referencing 4.03 where Cas first talks about Sam heading down a dangerous road and says if Dean doesn't stop him Team Angel will. Doing this scene's really weird now Cas and Ruby are practically drinking buddies XD]
“Then why is she still alive?” Cas, on the other hand, at least seemed calm, having the benefit of clarity on this matter if, granted, not many others these days. A demon was and always would be a demon – surely Dean understood this? Castiel did not believe that a hunter's upbringing could so easily be put behind based on a few testimonies from a less-than-reliable source – Sam Winchester, Sam the abomination, clearly being far from the best judge of character. Besides, even if he had been an upright citizen and not the nearest thing to hellspawn? Castiel knew how demons worked.
He only hoped she had not managed to infect Dean.
“I take it this means you believe your brother can be trusted around demons?” Okay, maybe that was – what was the phrase? - hitting below the belt. Castiel preferred to see it in less dubious terms; sometimes humans needed to be confronted with the harsh truth rather than coddled, however much it would no doubt pain the elder Winchester to revisit those particular strains of thought. “In that you are alone. You know where this path leads, Dean.”