Meet the face of 'Orphan Black' male clones

Ari Millen was thrilled just to have one role on clone drama Orphan Black. But four?

"It was very, very exciting," says the Canadian actor, who pulls quadruple duty in the third season of BBC America's sci-fi hit, returning Saturday (9 p.m. ET/PT).

Millen first appeared in Season 2 as Prolethean cult follower Mark, who was destined to be killed off by midseason. But after co-creators Graeme Manson and John Fawcett kept extending Mark's life, they eventually clued in Millen on their plan to make him the face of the series' male doubles, a product of a military operation called Project Castor.

As questions swirled about the genesis and purpose of the multi-ethnic female clones — known as Project LEDA, and all played by Tatiana Maslany — "We knew we needed male clones, and the whole question as we were writing was, 'Who's it going to be?' " Fawcett says.

Impressed by Millen's performance but unsure of how else to continue Mark's role in the narrative, Manson wondered, " 'Are we going to cast someone new to play the male clones, or can we go to our ranks and make it part of the mythology, and use someone that feels like they've been planted?' That was a Eureka moment for us, where we were like, 'That's what we can do with Ari, and I think Ari can pull it off.' "

Season 3 picks up mere hours after main clone Sarah Manning discovers the Castor brethren, clashing with them as she attempts to reunite her own LEDA clan. It "jumps right into the mystery of, 'What are Project Castor? Why do they exist? And how does this affect LEDA's world that they are starting to come to grips with?' " Millen says. "The theme of the season is family, and you're definitely going to see that in the brotherhood and Project LEDA's extended family, learning about who you can and can't trust."

Juggling multiple characters could have been daunting, but Millen had a seasoned pro in Maslany for guidance. After all, the breakout actress has embodied a dozen diverse clones, dead and alive, in the show's two seasons. Playing as many as four women in one scene — the fan-favorite "clone dance party" in the Season 2 finale — Millen says he learned the most from watching her, a sentiment she echoes.

"I was really impressed when I saw his first clone scene, because he had such an ease with it and such a relaxed quality to it, whereas I remember just feeling terrified and panicked when I first started (them)," Maslany says. "We definitely chatted about it, but it's such a personal experience, and there wasn't any advice I could really give, except, you know, to enjoy the craziness of it."

Unlike the LEDA clones, who come from different parts of the globe and have distinct personalities, the Castor brothers were raised together and share similar attributes. Although their roles vary — Miller is a hard-nosed soldier; Rudy, a scar-faced prisoner; and Seth, a mustachioed brute — Millen's biggest challenge was making them stand out as individuals.

"In the beginning, it was discovering those little differences, not only for them, but for the audience to know who's who," Millen says. "On a multiple-clone day, sometimes it was difficult to shake one and get into another, but luckily we had a great script supervisor who was always watching and would pull me aside, like 'You're a little bit too Rudy now, I need more Mark.' And I was like, 'Oh, well, thank you very much.' "