Warning: The following story contains MAJOR SPOILERS about Avengers: Age of Ultron.
One of the best surprises of 2012's The Avengers was the re-reintroduction of the Hulk, and of Mark Ruffalo as his alter ego Dr. Bruce Banner. (Eric Bana first played Banner in 2003's Hulk, followed by Edward Norton in 2008's The Incredible Hulk.) Ruffalo and writer-director Joss Whedon earned praise for finally finding the right mix of barely contained rage, playful intelligence, and tortured melancholy for Banner. But Whedon was still frustrated that he was limited by how much he could use the Hulk due to the enormous cost and time spent to digitally animate his actions.
"Every time you see the Hulk, it's going to be a shot about the Hulk, because we can't afford to have him in a shot that's not about the Hulk," Whedon told BuzzFeed News about the first Avengers film. To solve that problem for the sequel, Avengers: Age of Ultron, currently in theaters, Whedon and Ruffalo turned to Andy Serkis and his motion capture studio The Imaginarium to allow Ruffalo's acting to drive the Hulk's performance.
"This movie, we got to shoot him just as a character," said Whedon, meaning the giant green rage monster could appear in touching, quiet moments with Black Widow (Scarlett Johansson), or in the background as Hawkeye (Jeremy Renner) or Captain America (Chris Evans) battle in the foreground. Ruffalo’s motion capture work is the latest evolution of one of the most beloved, and complicated, characters in the Marvel Cinematic Universe — and, it turns out, it’s also an indication of where he might head to next.
In Hulk's biggest standout scene, the powerful Scarlet Witch (Elizabeth Olsen) messes with Banner's mind so badly that he sends his alter ego on a berserker rage through downtown Johannesburg, forcing Iron Man (Robert Downey Jr.) to take on a giant Hulkbuster suit to subdue him. Even for these rubble-strewn scenes of wonton destruction, Ruffalo was in the driver's seat of the character's roiling emotions.
"I did all the motion capture for that," said Ruffalo. "So when I get hit in the face, and I come back up and I spit the tooth out, that's me." For a beat when Stark repeatedly punches the Hulk's face into the pavement, Ruffalo mimed his face getting pummeled into a mat. And while a muscle-bound stunt performer named Rob de Groot (Guardians of the Galaxy) also served as a motion capture reference for the Hulk, Ruffalo said that he strives to play the character even for the bigger action beats, like when the Hulk throws a car at Iron Man and then punches him through it. "They'll give me a big piece of foam [or] a cardboard box, just to get that size and that mass, basically at scale. And then I'll throw that, or I'll run and I'll do the kick."
The biggest challenge came when Hulk’s rage dropped away for a moment and he began to register the devastation he had caused. "That's the problem of the Hulk," said Ruffalo. "When does Banner's consciousness start to dominate Hulk's? Where are those moments, and where do you play it?”
In fact, Ruffalo thinks that moment points to where the character could evolve. "What you want to see is the integration of these two egos," he said. "If you're doing this as a psych major, it would be the integration of a multiple personality person, you know? … What is Hulk afraid of? He's afraid of Banner. That was something I found in this movie that never would have crossed my mind. But he's terrified of Banner, that vulnerability. And Banner's terrified of Hulk. So there's some interesting places we could go, if we could figure out how to crack the nut of the story."
The end of Age of Ultron does indicate a possible future storyline for the character: Hulk deliberately flies away from the climactic battle in a cloaked Quinjet and goes into hiding, convinced he is too much of a danger to society — and especially to Black Widow, with whom he had a growing romance. "He tricked himself to think that he could have a normal life," said Ruffalo. "But then again, is it Banner, or is it Hulk? We're getting into this interesting bleed into the two of them."
When, or whether, Ruffalo could get to explore that duality between Hulk and Banner in upcoming Marvel Studios movies, however, remains unclear to the actor. "I don't know where I'm going to pop out again," he said. "I don't think they really know quite yet. I'm pretty sure I'm not in [2016’s Captain America: Civil War], or I certainly haven't asked to be in it. I think Banner and Hulk are just a long, long, far away from the rest of the team at this point. I think that it will be interesting to see where he ends up, and who he ends up with, just to see what's going on with him. … But I think we have everything available to us to do it. Now, the technology's there, where you can really do a nuanced performance with the Hulk, like a real performance. The world's set up well. There's a lot going for it if we could find what the story is."