Castiel frowned when Kobayashi went so far as to try and hide his rash and brush it all off. If he didn't take this seriously, then it wasn't going to end well. This was reminding him of his conversation of Aigis earlier in the day. How could people be faced with the threat of literally turning into an uncontrollable monster and not feel compelled to act?

"That means both of us run the risk of turning, possibly even tonight," he pointed out bluntly. "And Barnaby is caught up in it as well." It really wasn't his job to worry about others, but in this case it was his roommate, so he had a vested interest.

While he had already worked out his own situation (and his hope was that it would all go smoothly), that clearly wasn't the same for others. "What do you plan to do about it?" he asked. Ignoring it obviously wasn't going to help.