Sheen, a longtime fan and friend of Neil Gaiman, explained that the author and showrunner initially wanted him to play demon Crowley in the Amazon series.
However, when Sheen first read the script, he realised that Crowley was not the role for him, and that he would be better suited to playing angel Aziraphale.
Luckily, Gaiman felt the same way.
“[Neil Gaiman] sent me one of the scripts, an early draft of the first episode of Good Omens,” Sheen told his co-star during an episode of David Tennant Does a Podcast With… “We started talking about me being involved and doing it. He said, ‘Would you be interested?’ I said of course I would.
“At that point, he had always said about [me] playing Crowley,” Sheen added. “As time went on, and I was reading the script, I was thinking, ‘I don’t think I can play Crowley.’ And I started getting a bit nervous. I thought, ‘I don’t want to tell Neil that I don’t think I can do this,’ but I just felt like I couldn’t play Crowley.”
Sheen added that he felt on a “gut level” that he would be better suited to play the fussy Aziraphale rather than the free-wheeling Crowley, but felt “scared” to tell the author that he might be making a mistake.
In fact, according to Sheen, Gaiman was thinking the exact same thing.
“He hadn’t wanted to mention it to me, but he was thinking, ‘I think Michael should really play Aziraphale.'” Sheen said during the podcast. “Neither of us would bring it up, and then eventually we did. It was one of those things where you go, ‘Oh thank God you said that!’”
Sheen added, “And then I think within a fairly short space of time, he said, ‘I think we’ve got David Tennant for Crowley’. And we both got very excited about that, and then all these extraordinary people started joining in.”
As Crowley and Aziraphale, Tennant and Sheen’s on-screen relationship is the major driving force of the new six-part series, set to be released on Amazon Prime Video on 31st May 2019.
Gaiman has previously talked about the moment he realised that Tennant would be the ideal fit to play Crowley.
“I just remember the moment where I was half-way through writing episode three,” he said. “Suddenly I had an idea for a scene which involves some physical comedy, and I thought, ‘I don’t know who could pull that off? That’s really difficult.’
“And suddenly I thought: ‘David Tennant could pull that off.’ And suddenly the way that I wrote Crowley from that moment changed. And I was absolutely certain and determined that David would be my Crowley.”
In the podcast, Sheen explained how he had first been introduced to Gaiman’s work by a friend in drama school, and later met the man himself after mentioning that he was a fan during an interview.
He added that because of his close relationship with both the author and the novel, he feels a dual responsibility to do justice to Good Omens.
“For me, for someone who has been a fan of him and a fan of the book for so long, I can empathise with all the fans out there who are like, ‘Oh they better not f**k this up’,” he said. “I have that part of me, but then of course the other part of me is going, ‘But I might be the one who might be f***ing it up!’ I feel that responsibility as well.”