Well, in some fanfiction, Tony Stark might be kidnapped by a group who wants to use his genius to solve a world - ending problem their way. They believe that Stark, being forced, can come up with a solution faster. It could also be that a rival company kidnaps him to get an edge in the technology race. They take him to an unknown location and try to make him work for them against his will.
A possible plot is that a group of super - villains kidnap Tony Stark as a part of a larger plan to take over the Avengers. They figure that without Stark's resources and intellect, the Avengers will be weakened. They keep him in a high - security prison and try to break his spirit. Meanwhile, the Avengers are on a desperate search to find and rescue him.
One plot could be that a powerful enemy kidnaps Tony Stark to steal his Iron Man technology. They hold him in a secret lair and try to force him to reveal all the secrets of his suits. Another could be a fan with an extreme obsession who kidnaps him, thinking they can make him see things their way. Maybe they want him to create a special weapon just for them.
It could be a disgruntled former employee. Maybe someone who felt underappreciated by Stark Industries and decided to take revenge by kidnapping Tony. Another possibility is a new super - villain who wants to make a name for themselves by taking on Iron Man. They see kidnapping him as the perfect way to get attention.
The Avengers would be in a state of panic and fury. Captain America would likely lead the charge to find Tony. He'd use his military strategy skills to plan a rescue mission. Thor might use his godly powers to track down any signs of Tony's whereabouts. Black Widow and Hawkeye would be on the lookout for any Hydra agents or informants. Hulk could be a wildcard. He might be uncontrollably angry and ready to smash anything in his path to get to Tony.
One idea could be that Tony is kidnapped by a group of his tech rivals who want to steal his latest Iron Man suit designs. They hold him in a secret underground lair. Another could be that a fan-turned - villain kidnaps Tony because they think he didn't do enough to save a certain character in the Avengers' battles. Or maybe a powerful alien race kidnaps Tony to force the Avengers to give up some powerful artifact they possess.
Well, one possible plot could be the daughter trying to prove herself to Tony despite his initial rejection. Maybe she has some amazing scientific skills that she uses to solve a big problem, and in the process, she starts to earn his respect.
One possible plot could be Tony Stark, as a female, facing the same challenges in the tech world but with added sexism to overcome. She might have to prove herself even more than her male counterpart did. Another could be a female Tony Stark in a romantic relationship with a different character, like Thor, and how that changes the dynamics of the Avengers. Also, she could use her femininity in unique ways to solve problems, for example, using charm and guile where the male Tony might have used brute force or pure intellect.
One interesting plot could be the daughter suddenly showing up at Stark Tower. She might have grown up in secret, perhaps because her mother wanted to protect her from the dangerous world that Tony Stark is often involved in. She then has to navigate her newfound relationship with her father and all the high - tech and superhero craziness that comes with it.
One idea is that the Tony Stark Avengers toy is a prototype for a new type of weapon in the Avengers universe. The bad guys get wind of it and try to steal it. The other Avengers toys, with Tony Stark at the helm, have to protect the prototype. They use their unique toy - like abilities, like the Hulk toy's super strength and Captain America's shield - throwing ability of the toy version, to fend off the attackers.
One interesting storyline could be Tony Stark leading the Avengers in a battle against a new, powerful alien threat that has technology far beyond Earth's. He'd use his genius to analyze the enemy's tech and come up with strategies on the fly. Another could be him dealing with internal conflicts within the team while still trying to keep them focused on protecting the world. Maybe a member has a personal vendetta against a villain that could put the whole mission at risk, and Tony has to step in as leader to resolve it.
One idea could be that the kidnappers are from a rival tech company trying to steal Stark's latest inventions. They hold him hostage in an abandoned factory and he has to use his wits and some makeshift gadgets to escape. Another plot could involve a group of villains who want revenge on Stark for past defeats and they kidnap him to lure his superhero friends into a trap. A third idea is that a mysterious organization kidnaps him to force him to build a powerful weapon for their own evil purposes.
Another plot could be that in a post - apocalyptic world that combines elements of both universes, Harry and Tony are the last hopes for survival. Harry uses his magic to fend off dark magical creatures, while Tony uses his tech to combat advanced technological threats. They must learn to trust each other completely to save both the wizarding and non - wizarding parts of this new world.