Inside Mark Ruffalo’s Transformation Into Twins for ‘I Know This Much Is True’

Mark Ruffalo I Know This Much
Courtesy of HBO

The combination of cutting-edge motion capture technology, a bond between actors and Stella Adler’s training allowed Mark Ruffalo to pull off the impressive double-act of playing twin brothers in the HBO limited series “I Know This Much Is True.”

In the adaptation of the 1998 novel by Wally Lamb, which debuts Sunday, Ruffalo portrays brothers Dominick and Thomas Birdsey. Dominick is a blue collar, guy’s guy construction worker while Thomas is chubby and deeply sensitive man, who has been institutionalized due to mental illness. 

With Ruffalo playing two characters, the six-episode series, written and directed by Derek Cianfrance, had to be shot out of sequence. When Ruffalo first approached Cianfrance about collaborating on “I Know This Much Is True,” the actor admitted that he wasn’t aware of many instances where one actor playing twins really worked well in an adult drama.

“Usually, it feels like the actor has just run off and put a wig on and changed clothes,” Ruffalo tells Variety. “You never really feel like there’s two distinctly separate people there.”

Both men were wary of falling into obvious gimmicks.

“I was worried about embarking on some big technical movie,” said Cianfrance. “There’ve been so many movies and shows about twins — Cronenberg’s ‘Dead Ringers,’ Kevin Kline in ‘Dave,’ and that James Franco show ‘The Deuce’ — where you spend half the time as a viewer trying to figure out how they did it and what the trick was.”

Instead, Ruffalo and Cianfrance worked out a plan to use facial motion capture technology and actor Gabe Fazio (“A Star Is Born”) to help Ruffalo pull the double shift.

First, Ruffalo shot all of his scenes as Dominick, which required him to loose 15 pounds. He become wiry and assumed an ultra-masculine air. On set, Cianfrance says, Ruffalo could be “angsty” and “a bear to wrestle with.” But Ruffalo’s attitude completely changed when he was back on set, assuming the role of Thomas.

“When he was Thomas, he was so fragile that I had to approach him with kid gloves,” says Cianfrance. “It was like working with two different people. That takes so much skill and commitment.”

For Thomas, whose body is bloated by the heavy pharmaceutical medications he takes to control his illness, Ruffalo took a six-week break to put on about 30 pounds. The acting challenge for Ruffalo was making sure he was in the heads of both characters even while shooting one at a time.

“I had to have both characters in my pocket when I walked on set every day,” Ruffalo says.

The physical transformation was startling.

“The crew gasped on Mark’s first day back on set,” says Cianfrance. “Your physical body can really effect your internal self. Mark came back as a completely different person.”

“I Know This Much Is True” has relatively few scenes with Thomas and Dominick together. For those, Ruffalo worked with Fazio, who also gained and lost 30 pounds during the course of production. In one scene where Thomas and Dominick embrace, Ruffalo’s motion-capture face was pasted on to Fazio’s body.

Ruffalo was so impressed with Fazio’s work that he at one point tried to persuade Cianfrance to do the whole series with the facial-capture approach.

“Gabe was brilliant,” Ruffalo says. “I told Derek, ‘Gabe is so good why don’t we just (put) my face on to him. Derek was like ‘No, man, you gotta do it.”

While he was figuring out how to convey the physical and emotional distinctions between the two dramatically different brothers, Ruffalo spent time with Philip Ettinger, who plays Dominick and Thomas as young men. Before shooting started, the two men met at a New York City diner, where they  talked about their ideas for the roles. After eating, they walked for forty blocks, assuming the posture and gait of the different characters and fine-tuning their physical tics.

“He was so generous with me,” says Ettinger. “We just went back and forth, trading ideas, and he’d be encouraging me to make my own strong choices. This whole goal was to make it as realistic as possible.”

Playing two very different men in the same narrative gave Ruffalo insights into the nature of masculinity and the pressure that men face to present a certain public image. Thomas’ mental illness makes him more outwardly vulnerable less aware of social dictums.

To play Thomas, “I had to let my stomach go,” Ruffalo says. “I’ve spent my whole life as a man to holding in my stomach to show that I’m masculine. To make a conscious effort to let that go — it’s really interesting and you just see the impact of what male expectations of masculinity have on you psychologically and physically. None of us are aware of it. It’s like the ocean we swim in. Thomas is feminized in a strange way. He’s so open he doesn’t feel any of that.”

Ruffalo said the physicality of Thomas came to him in a bizarre dream about a furry rodent. “I had a dream about chubby little marmots in a tight-fitting suit,” he says.

Dominick, meanwhile, “has an armor on him,” Ruffalo says. The actor was having trouble nailing his first scenes as Dominick until Cianfrance had an idea.

“He said, ‘Do 50 pushups before we do this next take,” Ruffalo recalls. “I did a bunch and when I came up it made my upper body so tense and I was a little bit out of breath. That’s when we found Dominick.”

There was a method behind the madness.

“I just had this idea of the guy being all gorged muscles, with pumping and surging blood, and a shortness of breath,” says Cianfrance.

Kathryn Hahn, who plays Dominick’s ex-wife in “I Know This Much Is True,” said Ruffalo’s transformation was so complete as to make the rest of the cast forget he was playing both parts.

“I was completely taken aback at how he did it,” she says. “You completely forget that it’s one person giving us those two performances.”

The mix of technology and technique on display in “I Know This Much Is True” is generating rave reviews for Ruffalo’s performances.

Casey Bloys, HBO president of programming, said there was never a moment’s doubt that Ruffalo was up to task of playing twins. Producer Gregg Fienberg and vfx supervisor Eric Pascarelli were also invaluable to figuring out production processes that would allow them to make changes along the way if need be.

“I knew that if anybody could figure this out and make it feel realistic, it would be Derek,” says Bloys.

As is often the case, Ruffalo says he leans on his early training with the legendary acting teacher Stella Adler for inspiration when pressed to act in unnatural circumstances. His deep experience with motion capture technology from playing the Hulk in a string of Marvel movies went a long way to making him comfortable with the technology used in “I Know This Much Is True.”

“Stella said, ‘You must use your imagination.’ I keep hearing her screaming that at me as am standing there in a green screen box fighting creatures from another universe (as Hulk),” Ruffalo says. “So much of my training was about creating a world in your imagination. A lot of that training was the perfect antidote to this new technology.”

(Pictured: Mark Ruffalo as Thomas and Dominick in “I Know This Much Is True”)