When called directly by God, Castiel wasn't one to keep him waiting -- he owed so much to Him; everyone did. Still, that devotion didn't extend to the once fallen angel following God's words blindly. And it certainly offered no comfort when he stood before God and a seemingly pardoned Lucifer.
Castiel noticed that Gabriel looked distinctly ruffled by their long-since-banished brother's unexpected presence. He frowned and furrowed his brow, not entirely sure what to make of the situation unfolding before him. Shock wasn't quite the right word for the moment, but surprise wasn't quite adequate either. Suspicion and anger felt far more appropriate. (A feeling that almost any of the angels in Heaven would have likely have shared had they been there to witness this bizarre turn of events.)
Lucifer had been the enemy for a long time. There weren't many left who were old enough to remember the Archangel's betrayal of God personally, so many of their brother's had been lost in the last handfuls of centuries, but Castiel was definitely one of them.
God, or "Chuck" as he'd become known as, (long after the passing of Dean and Sam, where the whole schtick had started) abruptly disappeared after his brief announcement, leaving the angels and one human to stare dumbly at each other for a few moments of silence, but it was broken by Gabriel.
"Want... water?"
Castiel narrowed his blue eyes in their direction, still not mentally on board with the edict his Father had just issued -- it left far too many questions hanging in the balance. Why bring Lucifer back now? How could all be forgiven so easily when the Archangel had been locked away for so long?
For the first time in many, MANY years, Castiel felt somewhat sick to his stomach. (And he didn't even know if that was actually possible, considering.)
"Jackson," Castiel finally said, his gruff voice directed toward the one human in the room, a definite edge to his tone. "Meet Lucifer."
Any hunter would know the name, of course, even regular people knew the name and stories that were attached to it. Whether they actually believed in 'the Devil' being real or not was another matter. Lucifer had been safely hidden away and kept out of trouble since the time of Sam and Dean Winchester, who had long-since become the source of legends themselves.
Castiel's posture was stiff and his fingers had curled into loose fists at the sides of his perennially trench-coated attire -- he almost looked as though he was readying himself for an attack. He was unsure of Lucifer, to say the least, and wouldn't rule a sudden move of treachery out. It was always best to be prepared. Especially with Jackson present.