Benedict Cumberbatch says that Robert Downey Jr. and Tom Holland's improv skills inspired him to go off-script and call Iron Man a 'douchebag' in 'Infinity War'

Cumberbatch told The Hollywood Reporter that there was a "ripple effect" on set when he uttered the insult but was glad that it was kept in the movie.

• Benedict Cumberbatch told The Hollywood Reporter that he improvised a line in "Avengers: Infinity War."
• The actor went off-script when his character, Doctor Strange, called Tony Stark a "douchebag."
• Cumberbatch was inspired by costars Robert Downey Jr. and Tom Holland's improv skills.
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Benedict Cumberbatch improvised one of Doctor Strange's best lines in "Avengers: Infinity War" after being inspired by Robert Downey Jr. and Tom Holland's skills.

In a new interview with The Hollywood Reporter, Cumberbatch recalled working with Downey Jr. (Tony Stark/Iron Man) and Holland (Peter Parker/Spider-Man) for the 2018 blockbuster Marvel movie. Seeing Downey Jr. and Holland go off-script while filming inspired Cumberbatch to follow suit during a scene that appeared early in the movie.

While at the Sanctum Sanctorum, Dr. Stephen Strange and Tony squabbled about how to prevent the antagonist Thanos (Josh Brolin) from acquiring all six Infinity Stones. After Doctor Strange said that it's up to them to do their jobs, Tony made fun of his sorcery skills and retorted: "What exactly is your job, besides making balloon animals?"

In response, Doctor Strange said, "It's protecting your reality, douchebag."

"I remember on the set when I called him a douchebag, there was this sort of ripple effect. 'Oh my God. Did you just call Iron Man a douchebag?'" Cumberbatch told THR. "They kept it, good for them. And then, it got the same kind of response at the cinema."

The Oscar-nominated actor said that the improvised jab arose because he "got bored of being compared to Liberace or whatever other retorts the guy with the same camp goatee had opposite me, so I tried to knock him down."

He added: "It's great fun to play with that stuff. You find your feet. The more times you do it, the more familiar it becomes."

In addition to Cumberbatch's aforementioned line, Holland also improvised one of the most heartbreaking moments in "Infinity War," which centered on Peter and Tony.

During the scene when Peter began turning to dust because of Thanos' snap, the webslinger told Tony that he "didn't feel so good" and repeated the line, "I don't wanna go."

Holland told Fox 5's Kevin McCarthy that it was "improvised to a degree" and that "the scene was never meant to be as dramatic as it was."

"We improvised a version of the scene which wasn't great, but it sparked an idea of, 'We should have this embrace and I should turn to dust while he's holding me,'" the actor said.

Holland's ability to improvise with Downey Jr. was an extension of their close bond that began when the British actor auditioned for Spider-Man several years ago.

Holland described the extensive audition process as "horrible," but called his screen test with Downey Jr. "the best audition I've ever done."

"He and I were riffing off each other," he told Daniel Kaluuya for Variety's "Actors on Actors" series in 2021. "My agents told me that Marvel likes you to learn the words exactly - you can't improvise. And then, on the first take, Downey just completely changed the scene."

Marvel Studios president Kevin Feige later praised Holland for "keeping up with him off book to some very funny ad-libs."

Tony's storyline in the MCU has run its course, but Holland and Cumberbatch will reunite for the third "Spider-Man" installment titled "No Way Home," set for release on December 17.