The admission didn't surprise Balthazar. If you looked long enough at Dean, you could see the darkness in him that wasn't in the other one. Was the other Dean capable of dark things? Yes, of course, but there was a difference in doing it and doing it and liking it. Balthazar would wage good money this one enjoyed what he did. Except this one didn't have an excuse of being soulless, it seemed. Even more interesting.
However careful Balthazar had been, the question Dean asked finally pulled a frown from Balthazar. The frown was followed up by a look in his eyes that was a little more typical angel and less the hedonistic carefree 'rouge' he usually played at being. "I have no doubt you took the opportunity to kill me, Dean. Jo's a bit more surprising." But it helped paint an even better picture of who this Dean was.
"Castiel was sent home a week ago." He lied, but he didn't flinch. "If you must know, we were together, and yet the Dome saw fit to send him off back home to die for you."