Demons wouldn't be very good at their jobs if they weren't able to spot a sinner. It's not really a visual thing, but if Crowley tried to describe it physically, he'd say that sin is like those little clouds that hover above the heads of cartoon characters. Some clouds are puffy white, some are dark, some are storming. Everyone has one. Humanity can't exist without some sin, that's the whole point.

Crowley could theoretically curse Hannibal to die from a distance, but he wanted to see him in person. He's wanted to for months now, just for confirmation. Humans can control body language and voice and expression, they can craft such intricate lies, but there is nothing anyone can do about the soul. To a demon or an angel, the soul is always just right there, since it's the only really important thing about people in the grand scheme of things. Like a dog will notice a scent before anything else, a demon will notice a soul.

And there it is. Hannibal's little storm cloud, a miniature cold front. It's not even remotely the worst Crowley has ever seen, but it's there, plain as day. It's the last bit of confirmation he needed.

He puts on a smile and raises his glass in greeting.

"It is, isn't it? I find you can't truly know someone until you meet them in person. Well, I've been trying to get out more and properly get to know Wonderland's denizens lately. At least the interesting ones. Scotch?"