Several hours after dark on the day that Susan
wrote him about Katou, Crowley made his way invisibly down to the First Aid Station. It wasn't that he was actually invisible, but a demon wearing all black, with six thousand years of lurking experience, and radiating a 'you can't see me' field, is as close to as makes no mind.
He wasn't entirely sure why, but he wanted to check on the kid. Some vague sense of responsibility somewhere in an unused portion of his psyche at least wanted to make sure he wasn't going to die. But a whole lot more of his lingering righteous anger didn't want anyone to know he was doing any such thing.
The demon slipped noiselessly into the building and made his way back to Katou's bed. He'd stay for a couple of minutes and that was it...