"I believe I do know him." Not well, not at all, but enough to have a clear idea of the guy. "Striking eyes. Beautiful name, as well. Castiel. Just rolls off the tongue, doesn't it?" Dean, who clearly had warm feelings for the man, was unlikely to disagree.
"Is he as serious as he looks?" Cinna wondered as he regarded his work with a critical eye. Another snip here, right above Dean's ear, another there, right at his nape. "I've known some people like that -- they can reveal an impressive sense of humor, if you know how to coax them into letting it show."