The Adorable Reason Why Vin Diesel Decided To Play Groot

It's safe to say that one of the most vital elements of the Marvel Cinematic Universe ever since Robert Downey Jr. thought he'd give the role of Tony Stark a go is the casting. This ever-expanding world of heroes and villains has only been as strong as the stars who played them, and for the most part, they've been perfect. Now, after nearly 30 films have come and gone, there's barely a name behind a heroic alter ego that doesn't belong.

One standout ensemble that rocks the MCU in all the right ways is the Guardians of the Galaxy. Before writer and director James Gunn put "Peacemaker" on the map, he gave an intergalactic group of underdogs something to fight for, and all the actors who play them are a perfect fit for their relevant roles. One in particular is "Fast and Furious" frontman Vin Diesel as lovable leafy hero Groot. Although his lines are bound by only three words, Diesel was initially reluctant to take the role. Thankfully, his reluctance quickly dissipated once he heard the opinion of one of the smallest members of his family. And as everyone knows, "You never turn your back on family."

While Vin Diesel wasn't initially enthused about the idea of voicing a tree that could only say three words surrounded by a gang of smart-mouthed misfits, James Gunn and president of Marvel Studios Kevin Feige likened the role to one of Diesel's favorite fictional gentle behemoths: the Iron Giant. Torn, Diesel tested out the potential role on his kids to see if that's where he'd fit in the MCU.

Speaking to "Extra" host Maria Menounos in a 2013 interview (via YouTube), Diesel said, "I took the book of conceptual art into the room with my kids, and I opened it up to the page where all five Guardians of the Galaxy characters are, and I say, 'Who do you think they want daddy to play?'" The response seemingly was without any hesitation: "My daughter so quickly pointed to Groot. From that moment on, I was Groot." The outcome led Diesel to join one of the most beloved superteams in comic book movie history and allowed him to grow into a role that we can't imagine being without.