Can't get into detail due to professional blah blah, but the King of Hell is aptly cast.
I finally posted this story elsewhere so I figured I might as well paste it here.
I was the guy-who-takes-your-money at the table of Mark Sheppard (Crowley in Supernatural) for three days at a con in Orlando in 2014. He could be effusive with someone if they shared a common interest (he liked talking about fixing up cars), but was low-key insulting at other times. A local would come up and say "welcome to our city", and he'd say "you don't have a city. You have a parking lot for Disney and Universal," and, stunned, they'd try to salvage the experience in some sort of positive direction.
He got to talking to me about the UK sitcom Father Ted, which at that point I hadn't heard of. He delightedly told me about how it, in his view, is "anti-Catholic". Now, I'm not Catholic, but I could've been for all he knew.
At one point there was no one in line (there never really was one, the con was a bust due to a bigger con having rescheduled to the same weekend), and about 50 feet away a shy fan was eyeing the table, working up the nerve to approach. I pointed her out to him, thinking maybe he'd like to make a fan's day, but he said, "no, I'm good, mate". He thought I meant he could make another few bucks. (The table take wasn't even going to come close to his guaranteed minimum fee, so he was on cruise control.)
He also raised a big stink at the end of the day about how he'd get that fee. No checks, and in large denominations so that he wouldn't be carrying a giant bag of cash on the plane. The organizers had to find a bank OPEN ON SUNDAY to exchange a bunch of 20s from the admissions take into 100s for him. Was extremely rude to the staff.
That's the only time I've ever worked behind a celebrity table. A friend was helping organize the con and recruited me. She sold me by promising I'd be handling Joel Hodgson but that got changed at the last minute.
I delude myself with the notion that I would've so impressed him with my wit that I'd have been invited to write for the MST3K revival that he started putting together the following year.