Zachariah did not turn around when the familiar presence of no other than Castiel himself echoed through the interior of the room. Hands clasped behind his back, the angel quietly stepped over to examine a painting - it was of their own brother, Michael - as though Castiel's arrival meant absolutely nothing to him. That was far from true, of course. Castiel had his many uses, so long as he stood his ground and played the role that he had been given. That was key to the success of their mission; without Castiel guiding the Winchesters to the finish line, without him there to prepare Dean Winchester for his moment of greatness, getting what they wanted was going to be far more difficult than Zachariah wanted. He was a good angel. He did his job when he was told and Zachariah always did it well. If an inferior angel like Castiel dared put all that he had worked for on the line...
Zachariah had never failed his family. He wasn't going to start doing so now; not because his snot-nosed little brother was behaving so moronically.
"Do you remember why you were brought to this earth?" Zachariah inquired, back still facing him. He eyed Michael's painting one more time before he turned, gaze falling upon the trench-coat wearing angel. Zachariah preferred his own wardrobe. His suit? It was far more classy. "Or has your exposure to the human race made you forgetful?" Zachariah shook his head, almost as though he were pitying him. "Word on the street is that you were last seen running from this country to the next in the company of a demon. A demon, Castiel?" Zachariah raised his brows, hands on either side of himself raising into a 'you have got to be kidding me' sort of gesture. "Better yet, it's that demon. The one that the Winchesters have taken in as their little pet. That wouldn't be such a terrible thing if you intended on smiting her, but - wait for it - I hear you've been drinking with her. Like a pair of humans. Two buddies, hitting up a bar, acting like everything is perfectly fine and dandy." Zachariah's eyes narrowed. "I do hope you have a good explanation for your behavior because we both know that your behavior is far from acceptable."
It was disgraceful. While, yes, Zachariah had been relying on Ruby to get Sam to the final seal in time, he was hardly going to up and become best friends with the vermin. How much lower could Castiel have gone?