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Ari Millen already loved his role on “Orphan Black,” but his joy quadrupled while filming the new season of BBC America’s hit clone drama.

“The fact that my screen time got multiplied this season only meant that I was going to get to do more fun and exciting stuff,” said the Canadian actor, who plays at least four clone brothers when the third season premieres at 8 p.m. April 18 across all AMC Networks.

Millen first appeared in Season 2 as Prolethean cult henchman Mark, who went after Sarah Manning and her clone sisters, all played by Tatiana Maslany. Mark’s clone brothers—Seth, Rudy and Miller, the products of a secret military initiative called Project Castor that was revealed at the end of Season 2—will make life difficult for the clone sisterhood of Project LEDA.

According to Millen, Maslany got the news of his quadrupled roles before he did from co-creators Graeme Manson and John Fawcett.

“She knew probably a day or two before I did that it was going to be me,” Millen told me. “So the first thing that happened when I got to set after I found out—and it was still a secret to the rest of the cast and crew because we hadn’t got the season finale script yet—she just sort of came up to me and gave me a little rub on the back and winked at me and said congratulations.”

Ari Millen

Sarah (Tatiana Maslany) confronts Rudy (Ari Millen). (Steve Wilkie/BBC America)

That support from Maslany continued throughout filming of the new season, which made juggling multiple characters a little less daunting for him. He and Maslany discussed their scenes, he said, but she didn’t offer advice unless he sought her out. “How do you act with those tennis balls so well?” Millen joked, referring to how a tennis ball on a stick sometimes stands in for one of the clones while the actor does scenes as another one.

Millen found that watching Maslany play her multiple roles was the best way for him to get tips on how to fulfill his new job requirements.

Maslany agreed that they talked about scenes and leaned on each other, but she said Millen seemed to be less terrified than she had been when she first started doing the multiple roles. (He also worked with a double, Nick Abraham, who would play his other clone.)

“When I saw his first clone scene—I saw a rough cut of it—and it was unbelievable,” she told me during a separate call with writers. “His understanding of the sort of technical side of it while still being able to be present and be relaxed and just not make it about the technical was really amazing. He was kind of a natural at it.”

That’s high praise from the SAG and Golden Globe-nominated actress, who has inhabited at least a dozen clones—including four at once in a Season 1 scene as well as the Season 2 fan favorite, the “clone dance party.”

“It’s very cool to watch somebody else go through the same process that I did,” the Canadian actress said.

Read more: Tatiana Maslany talks Season 3 of “Orphan Black.”

Although the technical aspects of their multiple roles are similar, the actors each had to find their own techniques to get into character.

Maslany has said she uses different musical playlists to get into the heads of the individual sisters. Millen, however, used a more visual process. Wardrobe, hair and makeup were his tickets into each of the brothers.

Rudy’s menacing scar and Mohawk gives away his unhinged nature. Miller, with his clean military haircut and prosthetic leg, is a disciplined, by-the-book soldier. Brutish, dimwitted Seth favors hoodies and a creepy mustache. Mark, now hiding out from the Proletheans and his brothers, fits in anywhere with his everyman appearance.

“If ever I felt like I was coming out of [character], I would go find a mirror and just sort of settle and take a breath and just look and drop back in,” he said. “It was a very different process for me than normal. But it still worked.”

The history of the Castor clones also made Millen’s situation different. The LEDA clones grew up in disparate parts of the world with different parents and siblings. Each is strikingly different in personality and style,  and they had no idea that the others existed while growing up.

The Castor clones were raised together as brothers by the shadowy military group for which they work. They share many attributes, including their loyalty to each other, their capabilities as soldiers and their ruthlessness. Millen had to make them stand out as individuals.

“The biggest challenge for me was finding the differences within the similarities. Finding the little nuances that make Rudy Rudy; that make Mark Mark; that make Seth Seth,” he said. “I guess on a multiple-clone day … just trying to drop one and pick up the other depending on how much sleep I got the night before might have been a bit more challenging.

“But yes, it was a really fun process of just trying to portray these guys within their brotherhood.”