When the knock came, Nathan didn't immediately put down his work, as he knew who was likely at the door, due to having Dean Winchester contact him about a meeting. With an almost deliberate slowness, he finished the brief in front of him, then set it down and went to answer his office door.
"Winchester." Though the tone he greeted Dean with when he opened the door wasn't the tone he typically reserved for, say, Bennet when dealing with Noah, there was a coolness there that spoke to Nathan perhaps not being entirely happy about what he suspected Dean wanted to talk about.
That was because he wasn't.
With a quick jerk of his head, he motioned Dean into his office, under the assumption they'd be having this meeting Dean had asked to have.