Rocket Man: How Guardians of the Galaxy actor Sean Gunn became an MCU MVP 

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How limber was Gilmore Girls actor Sean Gunn as a child? Let’s see if his older brother, Guardians of the Galaxy franchise director James, can answer that in the form of a really embarrassing story. “When Sean was 12 years old, he would amaze people who came over to the house by taking off all his clothes, and standing there in his tighty-whitey underwear, and fitting himself through a wire hanger without bending it,” says the filmmaker.

Three decades on, Sean’s flexibility has proved of huge value to his sibling. Ask fans who plays Rocket in the

movies, and they will likely answer “Bradley Cooper,” who voices the gun-toting rodent. But were you to visit the set of a

film, you would notice that the person reading Rocket’s lines and physically portraying him is Sean. You would also see that doing the latter requires the 43-year-old to maintain an uncomfortable crouched position, so as to be at correct eye level for his fellow actors and the effects team, who will later computer-generate the diminutive critter we see on screen. “I can crouch down and even walk from that position without too much trouble,” says Sean. “I don’t think many other actors would be able to do the physical part of it.”

Sean can thank — or blame — a certain sandwich-loving dog for his discomfort. “I wrote the Scooby-Doo movies,” says James. “I’d been through having Matthew Lillard [who played Shaggy] act with a tennis ball. I knew I wanted a real actor to play Rocket.” For 2014’s first

film, James cast Sean in the minor role of the space pirate Kraglin but also asked him to read Rocket’s lines while he figured out how to physically represent the character on set. “When we rehearsed the first scene, I just jumped in there,” says Sean. “I got on my hands and knees, essentially, so that when Chris [Pratt] and Zoe [Saldana] and Dave [Bautista] were speaking to Rocket, they were looking at a person’s eyes.”

films, the actor still felt he had to explain his role in bringing Rocket to the screen when he turned up last year to play the character for directors Anthony and Joe Russo in

Avengers: Infinity War. “I said, ‘Okay, here’s what I do, but you guys let me know if you want me to step back,’ ” says the actor. “Joe and Anthony were like, ‘We’re going to stick you in there with the cast.’”

So, does Sean mind that he does so much of the work to create Rocket while Cooper receives the bulk of the recognition? “It is strange to spend so many hours as a character and then see it and have it be neither my voice nor my face,” he says. “But I never did the job because I thought it would get me a lot of attention. I did the job because I wanted the movie to be as good as it could possibly be.”

Sean doesn’t even object to James telling embarrassing stories about his days as a child contortionist — well, not too much, anyway. “I’m, of course, grateful that he’s humiliated me in front of millions of people,” says the actor with a laugh. “But yes, that’s true.”