The Marvel Cinematic Universe has totally skipped what may be Tony Stark's most important story - just what happened to him between Spider-Man: Homecoming and Avengers: Infinity War. In those few years, it's becoming clear that he didn't just crack one new technology - nanotech - but that, instead, he had a whole series of breakthroughs. And Tony's work would undoubtedly have exerted real pressure upon his relationship with Pepper Potts.
When Captain America: Civil War came to an end, Tony and Steve Rogers found themselves on the opposite sides of a deep philosophical divide. With the Avengers fractured, Stark returned to the Avengers compound - in itself a declaration that he was returning to the superhero life. He, then, attempted to form a whole new team of Avengers, even trying to recruit Spider-Man into the group in Spider-Man: Homecoming. Crucially, though, according to the tie-in Avengers: Infinity War Prelude comic, Tony realized that attempt had failed. He still believed the world needed defenses, that the alien invaders he battled in 2012 would inevitably return; half-formed fears of a monster like Thanos still echoed in his mind. "If I'm gonna prepare for the end of all things," Stark reflected, "I'll have to do it alone." And so the billionaire genius playboy philanthropist settled down to begin a process of discovery that ultimately led to the creation of the Mark L armor.
But the Mark L armor is unlike anything Stark has ever fashioned before; recent Infinity War concept art has revealed that it involved not one, but at least three, major technological breakthroughs. What's more, some of them would actually cause major problems in Tony Stark's personal life. But that's never been explored by Marvel at all.
- This Page: Why Tony Stark's Armor Was So Revolutionary
- Page 2: So Why Is This A Character Arc?
Iron Man's Infinity War Power Source is Surgically Implanted
Iron Man has always been associated with distinctive chest units; back in the first Iron Man, after all, Tony was forced to implant a miniaturized Arc Reactor into his own chest in order to prevent shrapnel slipping into his heart and killing him. In Iron Man 3, a major plot point was that he finally decided to have the shrapnel extracted, meaning he'd no longer be dependent upon an Arc Reactor to keep him alive. From that point on - from Avengers: Age of Ultron through Spider-Man: Homecoming - the Iron Man armor's power sources were externalized.
But it seems that may not be quite the case for the new unit. According to concept art from Avengers: Infinity War, Marvel intended this new power source to be surgically implanted within Stark's chest. That explains why there's no hint that the weight of the chest unit is deforming Tony's clothes; Stark carries the weight himself, and there's a cut-out in his shirt (just as there was in Robert Downey Jr.'s clothes during filming).
Supporting this assertion is the fact that this doesn't seem to be an Arc Reactor at all. Instead, according to The Art of Avengers: Infinity War, Marvel insiders call this an "RT" unit. That name will be familiar to comic book readers; it's a so-called "Repulsor Tech node," a fusion-powered unit that (in the comics) Stark invented back in 2008. (Tony implanted it in Pepper's chest in order to save her life.) This is completely different technology to the Arc Reactor, and, in the comics, Tony considered it to be one of his greatest breakthroughs. It looks as though, in the MCU, he made it off-screen.
Iron Man's Infinity War Armor Evokes Memories of Extremis
Tony Stark's next breakthrough parallels another comic book arc, "Extremis." In this arc, Stark developed a neural interface between his nervous system and his armor. That meant he no longer needed to vocalize commands, blink at the right moment, or flex certain muscles to trigger responses from his suit. Instead, all he had to do in order to control the tech was think about what he wanted it to do. The armor responded to Tony Stark's very thoughts.
Looking closely at Avengers: Infinity War, it most certainly seems as though Stark has created a similar kind of biotechnology. The loss of Iron Man's artificial intelligence doesn't appear to lessen the potency of Stark's armor at all. In fact, during the battle on Titan, he controls the nanotech with effortless (and, indeed, wordless) ease. The suit transitions through a variety of forms in response to Tony's will, forming a wide range of weapons with no hint of a command. There definitely seems to be some sort of neural interface. Ironically enough, that's the kind of technology Marvel fans were expecting to see in Iron Man 3, but that film took a very different approach to Extremis.
Interestingly, the concept art hints that this idea was intentional. It shows a web of circuitry implanted into Stark's chest around the RT unit, covered by fake skin. The RT unit basically plugs into that, and it's probably detachable, explaining why Pepper wasn't happy when she saw it in the film. Presumably, then, the technology implanted in Stark's chest is the neural interface, connecting an RT unit to his mind. While Tony does need to flex and press the RT in order to trigger the tech, from that point on, it responds to his thoughts.