It was just two months before Riddick was set to hit theaters when Vin Diesel told his 46 million+ Facebook fans that Marvel Studios had requested a meeting with him. Diesel left of the meeting very excited and at Comic-Con while promoting Riddick (and every interview since) he couldn’t avoid questions about Marvel, leading to unofficial confirmations that he’s not only potentially joining the franchise in a major role years down the road, but will be enlisting with the Guardians of the Galaxy as a walking, talking alien tree. This is the story of how that happened.

Speaking with his friend and interviewer Maria Menounos, Vin Diesel explains how Marvel sold him on the idea of Groot in Guardians of the Galaxy and how he and Marvel are doing their best to appease the actor’s vocal online fanbase.

“My daughter said ‘yes’ to Groot… I came home and I had a giant… Marvel, they’re so shrewd. You have to understand, when I met with Marvel it wasn’t for anything immediate. It was to talk about a film that would be introduced in the Phase Three part of Marvel – So, not for a few years. You wouldn’t be able to see it for a few years, and in my mind Marvel was doing it right. They were enrolling me at the ground level which is the best way to enroll me.

I had heard over the last year people on the social media page saying ‘what’s up Vin? Why aren’t you going to Marvel? Why aren’t you doing anything with Marvel? It would be a crime of cinematic history for you not to be.’ So I’m thinking this Marvel thing is becoming really, really important to these people. Okay, what can I do? What should I think?

I get the call, I go down to meet with Marvel – a great meeting. I mean it was just… it was even talking about something so big I can’t even talk about because it’s like a merging of brands in a way which I won’t get into, but that was way, way, way, way down the road.”

Diesel explains how this all happened just a week before heading to Comic-Con for the first time in over a decade (since promoting Pitch Black) and that the very last question during the Riddick panel was about his potential involvement with Marvel. He explains that he was caught “like a deer in the headlights,” So, passing it off as cool and avoiding being “anticlimactic” by saying he’s working on something with Marvel for 2016, Diesel teased that fans should expect big news soon (read about it here – he saw this coming).

Marvel Studios and Diesel were shocked by how the news erupted and excited fans and the media so, despite Diesel’s packed schedule, Marvel Studios President Kevin Feige and Guardians of the Galaxy director James Gunn approached him with another idea. According to Vin they immediately contacted him the Monday after Comic-Con saying they still want to “focus on the 2016″ but they were sending over a package in two weeks to see if they can “if possible, answer this growing request for something now.”

“I don’t have six months to play a character in the immediate future. It’s all booked… There was no way I was going to be able to deliver. There was no way Marvel was going to be able to deliver. After Comic-Con we were at a stalemate. There was no way we were going to be able to answer the fans… And then Kevin Feige and James Gunn came up with something brilliant, even if I didn’t understand how brilliant it was when I first got it.

They sent over the script to Guardians of the Galaxy and they sent over a giant book of conceptual art… Everyone knows I’m a sucker for conceptual art… So, they sent over the visuals. I look at the visuals first and am like ‘oh my god.’ This is some of the best conceptual art I have seen in my life. But the request was a little bit ‘hmm… they want me to play a tree…”

That art is what led the actor to posting an image of Groot on his Facebook page. Diesel continues, “So they said, they wanted me to play a tree. They said there was something akin to Iron Giant about this tree, and everyone knows I’m a sucker for the Iron Giant. But I’m still like,” as he balances his hands and squints, emphasizing he was skepticism about the part.

“And another thing nobody knows, I always loved the Andy Serkis portrayal of Gollum as an actor and as a performer. I always thought that was one of the coolest challenges and one of the coolest things to do. If Peter Jackson would have asked me to play a dragon, I would have loved to have played a dragon, but to really mocap it. So, when Kevin Feige and James Gunn said we ‘want you to voice a character that historically is known for only saying one line’ it was not dissimilar to David Twohy saying ‘I want you to do Riddick but I don’t want you to interact with anyone in the whole first act.’ There’s something challenging about that and fun about that.

…to make sure I was on the right track 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?’ And my daughter so quickly pointed to Groot. From that moment on I was Groot.”

And that’s the story of how fans, his children and one meeting with Marvel led to talks not only for a major potential franchise years down the road, but a interesting and challenging new gig for Diesel in the immediate future for Marvel’s riskiest project yet.

Guardians of the Galaxy is directed by James Gunn off of his script co-written by Nicole Perlman. Cooper joins a cast led by Chris Pratt, Zoe Saldana, Dave Bautista, Lee Pace, Michael Rooker Karen Gillan, Djimon Hounsou, Benicio del Toro, John C. Reilly and Glenn Close.

Thor: The Dark World on November 8, 2013, Captain America: The Winter Soldier on April 4, 2014, Guardians of the Galaxy on August 1, 2014The Avengers: Age of Ultron on May 1, 2015, Ant-Man on November 6, 2015, and unannounced films for May 6 2016, July 8 2016 and May 5 2017.

Follow Rob on Twitter @rob_keyes for your Marvel movie news!

Source: conversationsMM (50:00 mark)