During a panel at C2E2 (via Syfy Wire), Mark Sheppard said that the idea of joining "Supernatural" was first brought up by his friend Kim Manners, who was a showrunner for the hit series until his death in 2009. "Pretty soon after [Manners' death] an audition came up for 'Supernatural.' They're like, 'Do you want to do this?' I just started laughing ... nothing had ever come across my radar before. ... It wasn't in my purview. And I was like, 'Yeah, this could be really funny,'" he said.
Sheppard would go on to charm the "Supernatural" family with Crowley's unique sense of humor, which included bickering with Castiel (Misha Collins) and bestowing the nicknames of "Moose" and "Squirrel" upon Sam and Dean. No matter how much fun he is having, strategy is always key to every decision Crowley makes. Much of that is designed with power and self-preservation in mind, and it's a mentality that brought Crowley to the Winchesters in the first place. Sheppard told Collider that Crowley's concern for himself is what stands out to him most. "I think Crowley always puts himself first, which makes it so much fun to play," he said.
During a 2018 appearance at New York Comic Con, Sheppard said that Crowley's exit was not his idea. As for the demon's return, he isn't ruling anything out. He said in an exclusive interview with Looper, "We've worked together over many years, so why shouldn't we work together again? Why shouldn't we try?"
