Most of the Avengers became Earth's Mightiest Heroes due to fantastical powers, but for Tony Stark it was always about his technological know-how. As Iron Man, he established himself as one of the world's greatest superheroes and one of the smartest men on the planet. What most people may not realize is he's not quite as human as they think, and there's a lot more going on in the anatomy of Iron Man than meets the eye.
What Caused Tony Stark to Become Iron Man
A single moment changes Iron Man's life forever. Although the specifics have changed over time from occurring amidst the Vietnam War, the Gulf War or the war in Afghanistan, his origin always comes back to the same event: a near-fatal accident that damages his heart. Typically the explanation is that shrapnel from an explosion embed itself in Tony's chest, necessitating the invention of an electromagnet to hold them at bay.
The event serves as the impetus to becoming Iron Man, and for much of Iron Man's early career, he's forced to wear the chest plate at all times for fear of the shrapnel stopping his heart forever. While he has the shrapnel removed in the MCU, the comic version needs a whole heart transplant in order to put the condition behind him. His heart may be stronger than ever, but the changes it causes to his character will last a lifetime.
Tony Stark's Bleeding Edge Tech Makes Iron Man's Suit More Accessible
Eventually, there's only so much tech Tony can fit onto his body, so it's only a matter of time before it starts to go into him. The Iron Man armor improves steadily throughout the years, but one of the biggest flaws in the early armor designs is how vulnerable Tony is outside of them, but that changes with the Extremis design.
With Extremis, Tony stores an undersheath in the very bones of his body that he can summon to cover him in an under armor. He can call the exterior plating of the suit to him, but even that process sees improvement over time. Once Tony improves the Bleeding Edge design, he discovers he can store the entirety of the armor in his bloodstream. As possibly one of his most powerful armor designs, the Bleeding Edge makes it so Tony is never without his deadliest weapon on hand.
Tony Stark Was a Superpowered Genius in Marvel's Ultimates Universe
In perhaps one of the most radical reinventions of the character, Marvel's Ultimate line of comics tells a story where Tony Stark outright has superpowers from birth. In the story, Tony's mother works on a biotechnology that can radically increase brain cell growth in an organism, but one of the test subjects infects her during a breakout. It turns out she's pregnant with Tony at the time, and the result is an embryo whose brain grows to encompass his entire body.
This version of Tony is born to be a super genius, but the condition comes with side effects. Since his entire body is composed of neural tissue, he's hypersensitive to pain, which necessitates either a coating of armor to protect himself or the numbing effects of alcohol. This version also has an impressive healing factor, allowing him to regenerate entire limbs. All in all, the idea gets a wilder than subsequent writers wanted, so the story was retconned as a "story within a story."
Tony Stark Had a Cancerous Relationship With the Mind Stone
In actuality, the "real" Ultimate Tony Stark suffers from a brain tumor that narratively serves the same purpose as the mainstream version's heart condition. While there's no shrapnel slowly killing the Ultimate Iron Man, the terminal cancer diagnosis has the same effect in causing the hero to reevaluate his life. He becomes Iron Man to try to give back to the world, but his story gets a lot weirder.
His tumor isn't actually cancer at all. Over time Tony becomes "friends" with the tumor and names it Anthony, at first thinking it's a mental construct helping him deal with his grief and talk through problems. Eventually, the tumor becomes capable of hacking into computer networks. After the Maker cracks open his skull, Tony discovers the tumor is actually the Infinity Gem, the Mind Stone, granted to him for his genius and helping him become a hero all along.
Tony Stark Is Trained to Fight Without the Iron Man Armor
However many wild stories he goes through, Tony Stark always returns back to basics. A normal man in an iron suit is at the core of his story and whether he drains all the nanites out of his bloodstream or gets his super tumor removed, there's always a back-to-basics approach for the playboy philanthropist.
That doesn't mean he just lets his body go to waste. Tony undergoes physical conditioning just like all the rest of the Avengers. He's even received hand-to-hand training from Captain America himself, so even without his armor, Tony is not lacking when it comes to his abilities in a fight.