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Genius, heiress, slut, philanthropist.
Oh, and superheroine. Can't forget that part.
You know the story; plutocrat and spoiled brat Toni Stark spent one too many years pissing off her father's old business partner who she ended up inheriting alongside Stark Industries and millions of dollars and got her ass kidnapped and stuck in a cave with some scraps. With a little help, those scraps became the Iron Maiden Mark I. Though, in fairness, everyone started out calling it Iron Man, which wasn't helped by Toni telling everyone at that press conference that it was her anonymous bodyguard. The lie didn't last long thanks to an especially disastrous birthday party where she and her best friend destroyed her house, which also allowed for SHIELD to step in and recruit her to their Avengers Initiative in exchange for not letting her die of palladium poisoning.
The rest of the world found out the real identity of "Iron Man" after the invasion of New York; Toni just learned how paranoid she really was, building a literal legion of suits to make sure everyone could be protected by her, even if she wasn't around. Once she stops Aldrich Killian and Maya from unleashing Extremis, though, she takes Pepper and Rhodey's advice and destroys the Iron Legion. While she still uses her resources to get Pepper cured of Extremis, she never bothers getting the arc reactor removed from her chest, citing that it's become part of her look.
Unfortunately for everyone, no one's really pushed her into therapy very hard at this point, so her paranoia only gets worse, leading her to create Ultron, causing all the disasters that sprang up from that decision as well as the birth of Vision and the recruitment of the Scarlet Witch. That leads to Toni supporting the Sokovia Accords, the Avengers' eventual split, Toni getting to learn what really happened to her parents back when they died, and Spider-Man.
Trying to figure out a way she can defend the world on her own, she creates the Mark L and upgrades her arc reactor somewhere between Peter's graduation as her intern and her first encounter with Doctor Strange.
Toni Stark is a bitch. She's unrepentantly sarcastic and quick to anger, bitter and traumatized and anxious, and a spiteful, on-again-off-again alcoholic who is all too aware of how freakishly smart she is. She is also, unfortunately, an extremely good person who mostly has the best of intentions despite being very fucked up. Between the mountain of trauma Toni's experienced and her unabashed narcissism, she very unfortunately realizes she's the main character and isn't afraid to remind people of that.
