HBO’s miniseries ‘I Know This Much Is True’ breaks Mark Ruffalo—in the best way

Mark Ruffalo wanted to break himself.

He just needed the room to do it.

Throughout his career, Ruffalo has bent himself into a variety of roles—in quirky comedies (The Brothers Bloom, Eternal Sunshine of the Spotless Mind), searing dramas (Foxcatcher, Spotlight), and, of course, the Marvel Cinematic Universe.

But there hasn’t been a role quite like what he took on for HBO’s six-part miniseries I Know This Much Is True.

And for that, he didn’t want to just bend.

He needed to break.

“I just wanted to push myself as hard and as far as I could,” Ruffalo says. “After almost a decade of Avengers, that can get really comfortable. I just wanted to break it up. I wanted to break myself up.”

Based on Wally Lamb’s 1998 novel, I Know This Much Is True follows Dominick Birdsey, a man in a desperate bid to get his identical twin brother Thomas (also played by Ruffalo), who suffers from paranoid schizophrenia, out of a dangerous mental hospital after he commits a crime. Along the way, Dominick battles his own grief and guilt toward his ex-wife and stepfather while unpacking a deep-seated family secret.

It’s a novel that’s been floating around Hollywood for years, but its sheer scope—clocking in at 901 pages—has made it tricky to adapt to film.

When Ruffalo caught word it was going to be optioned again, he secured a meeting with Lamb and pitched him on the idea of turning his tome into a miniseries instead. Lamb agreed, and Ruffalo brought on director Derek Cianfrance, whose work capturing the subtleties and heartbreak of working-class angst in such films as Blue Valentine and The Place Beyond the Pines made him the ideal fit for the blue-collar family drama at the heart of I Know This Much Is True.

Even better, like Ruffalo, Cianfrance was looking for a project that would match his ambitions at scale.

“With both of my last two movies, I felt like I ran out of space,” Cianfrance says. “In The Place Beyond the Pines, I naively thought that I was gonna make a movie that would have an intermission. And in the third act of The Light Between Oceans, I felt like I had to move so fast, I was only servicing plot.”

“[With I Know This Much Is True], there was this idea of telling an expansive story where we could actually service characters, service moments, and live in a space,” Cianfrance continues. “This is a show about family. What happens if you actually have to live with these people over a longer period of time?”

Having the space to really sit with a character served Ruffalo in the capacity of not only playing two different roles, but also requiring him to dissect how to portray someone with a mental illness.

“It was scary,” Ruffalo says. “You want to do it right.”

“There’s a certain behavior of dealing with schizophrenia. It’s the voices. It’s the paranoia. It’s the auditory and visual hallucinations. But schizophrenia isn’t a personality trait,” Ruffalo says. “Capturing Thomas’s duality to Dominick was really important. His sweetness, his gentleness, his femininity, his softness. There’s a mythological story being told here that’s couched in this kitchen-sink drama.”

Capturing that duality also meant figuring out how to shoot Ruffalo in scenes with both Thomas and Dominick.

“The North Star for how we approached this thing from the beginning was that actors would tell this story,” Cianfrance says. “This would not be a story told through the megalomania of filmmaking or a VFX technician’s dream. We decided, let’s just break this down to the essence of performance.”

Cianfrance relied on motion capture and some CGI, but it was by no means a crutch. In fact, Cianfrance went so far as to hire his friend and actor Gabe Fazio to give Ruffalo someone to play off of in scenes—even though Fazio’s performance will never see the light of day.

However, how he approached the project couldn’t have been simpler.

“I knew that Derek would want honesty and something stripped down and bare. In a strange way, it’s scarier to be that way, but also it’s simpler,” Ruffalo says. “You’re throwing yourself into the void. The more you prepare, the least ready you are for this kind of shoot. And that’s what I learned. So letting go was as much a part of accomplishing this as any heady approach would’ve been.”