Iron Man 3 included a subtle hint that Marvel planned to transform Tony Stark's AI, JARVIS, into Vision. Paul Bettany stands unique in the annals of the Marvel Cinematic Universe, the only actor to play two high-profile MCU characters on the big screen. He was introduced as the voice of JARVIS in Iron Man back in 2008, but in 2015 became the superhero known as Vision.

Named after Howard Stark's old butler, JARVIS - Just A Rather Very Intelligent System - started out as a natural language user interface system, created by Tony Stark. Naturally, over the years Stark tinkered with the AI, even uploading it into the Iron Man armors. Tragically, JARVIS was destroyed by Ultron in Avengers: Age of Ultron, but the AI's remaining codes were uploaded on the Internet and continued to thwart Ultron's attempts to acquire nuclear codes. Stark uploaded the last of JARVIS' code into a synthetic body, and he became part of a whole new entity - the android named Vision.

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It's a crazy, complex story, but amusingly Marvel dropped a subtle hint at it a full two years before it happened. Iron Man 3 was set in Christmas 2012, and featured a number of scenes in Tony Stark's house in Malibu. In the background, Tony has actually set aside a stocking for JARVIS, with his name stitched on it. It's an amusing touch, suggesting that Stark really does think of JARVIS as part of the family. But the key detail is the color of the stocking: it's red and green, the color scheme typically associated with Vision.

As Paul Bettany explained in an interview with Marvel Entertainment back in 2015, Marvel had the JARVIS/Vision twist planned out well in advance. Joss Whedon originally came up with the idea and approached Marvel Studios president Kevin Feige about it. According to Bettany, when Whedon was given the green-light he turned from director to fanboy in a second, thrilled at bringing one of his favorite comic book characters to life on the big screen. "I knew about this three years ago," Bettany reflected, "and I've been keeping it a secret." Given that filming didn't begin on Iron Man 3 until May 2012, there's no way someone in Marvel Studios didn't choose the colors of that stocking as subtle foreshadowing.

This is the best kind of Easter egg, as it's a subtle detail that's easy to miss but signposts the future of a major franchise character. It wouldn't have been hard for Marvel to do either; it's just a stocking in the background after all, and it's likely most of the cast and crew had no idea why Marvel had chosen that color scheme. In reality, they were pointing ahead to the future of JARVIS - and his transformation into Vision.

More: What Is Vision's Future In The MCU?

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