The Wheel of Time star talks becoming Moriarty in Young Sherlock - and the “form of love” between these iconic characters

This article appears in the new issue of Radio Times magazine, out Tuesday 24 February.

For Irish actor Dónal Finn, who plays James Moriarty, Young Sherlock is much more than just a ripping yarn. As much as he loved filming stunts and fight scenes, Finn believes the heart of the series is about two misfits finding common ground and a love for each other – even if that love is never expressed in so many words.

"We had a great reference in Butch Cassidy and the Sundance Kid, which I rewatched before we made this," Finn explains. "I was really moved by these two men who were in one of the most masculine atmospheres, the Wild West, and they’re not saying exactly what they feel, but they’re willing to die for the other person.

"That’s what we’re aiming for, because Sherlock and Moriarty do take risks for each other. That’s a form of love, and it’s not something that we see very often, although we are talking more about male loneliness these days. They both feel an element of loneliness at times, so this connection is important to them."

Like his co-star Fiennes Tiffin, Finn was a Holmes devotee, citing the Benedict Cumberbatch version as one of the key reasons he became interested in acting as a teenager. So the 30-year-old was aware that his character would later become the ultimate baddie, but had to put that out of his mind. "It’s like watching Titanic – you know how it’s going to end, but what are the circumstances that lead to that?" he says. "Moriarty’s internal code of ethics is still being developed when we see him, and he’s in a malleable place. I don’t think he was born with qualities of immorality; he’s having experiences that are going to shape the way he sees the world.

"I think there’s a blessing in that, although the characters are widely known, we’re meeting them at a point that no one has ever really met them. It’s just about them being young people, discovering they’re good at something in quite an innocent way."

Finn can relate. As a teenager growing up in Cork, Ireland, he enjoyed weekend acting classes but had no idea it would become his career. In fact, he had no idea there was such a thing as drama school until a teacher told him he should apply. Thanks to the Overstall Charitable Trust, he got a scholarship to Lamda, later landing roles in the original West End production of Hadestown as well as in the BBC’s SAS: Rogue Heroes and Prime Video’s The Wheel of Time.

"Acting was just a thing I did until it was time to go to university," he says. "It was amazing to find out that drama school wasn’t a fictional place, and to be encouraged by a teacher who had belief in me. He didn’t make me feel like I was a farmer from Cork. I felt like there was a place for me, for the first time.

"I never thought in my wildest dreams I’'d get a place at Lamda, never mind be playing Moriarty, a role that Andrew Scott and Jared Harris have both played. I understand the weight of that and I’m very conscious of how lucky I am to be playing a part that has been played by actors I deeply admire."

Finn’s performance is complex: as in the washerwoman prison-breakout scene, Moriarty and Holmes often wear disguises to keep one step ahead of the police, with Moriarty putting on different accents. "It’s so fun to impersonate a police officer and do a mad accent," Finn says. "Moriarty is like a cat with a ball of string: he and Holmes are sure they’re never going to get caught, they’re just exercising their wit and playing. Moriarty has a chameleon-like quality and draws on details of society to move up in the world without being noticed."

Another dream for Finn was working with Guy Ritchie. One of Ritchie’s key trademarks, says Finn, is characters who have an innate ability to handle high pressure situations in a cool and calm manner. "Guy’s characters are in high-stake situations, but they're able to adapt to them because their blood pressure is low and they’re managing not to stress out because they’re so cool," he says.

"It’s so pleasing to watch a character attaining a level of serenity and peace that you yourself could never access. And it’s so interesting, taking Sherlock back to ten years before the first Conan Doyle books, and asking what has to happen to a person in order for him to work in such a place of survival and instinct," he adds. "It’s a great question because he’s one of the most widely recognised figures in literature."

Read more: Joseph Fiennes talks Young Sherlock origin story and playing his nephew’s on-screen father

Young Sherlock is available from Wednesday 4 March on Prime Video.

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