They would immediately start looking for him. Natasha would use her spy network to gather intelligence on Hydra's possible hideouts. Clint would provide long - range surveillance. Steve would be the one to keep everyone focused and coordinated. Thor could use his connection to other realms to see if Hydra has any other - worldly help. Bruce, as the Hulk, would be a force to be reckoned with. They'd all be united in their goal to rescue Tony and take down Hydra for daring to kidnap one of their own.
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.
Tony would probably be extremely hurt. He trusted his team, and betrayal would cut deep. He might initially be in denial, not wanting to believe that his friends could turn on him.
In such a fanfiction, the plot might involve Hydra using Tony for his technological genius. They could force him to create advanced weapons for their evil purposes. Maybe they'd try to extract the secrets of the Iron Man suit technology. Another aspect could be Tony's attempts to escape while also trying to figure out Hydra's larger plan and find a way to stop them from within their lair.
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.
Steve Rogers would probably be deeply disappointed. He values loyalty highly, and Tony's betrayal would shatter the trust they had. He would try to find out the reasons behind it and might even try to bring Tony back to the right path if he thought there was a chance.
Some of them might be disappointed. Captain America, for instance, might feel that they've lost a great asset. But at the same time, he might also see it as an opportunity for the Avengers to be more independent from Stark's sometimes self - centered ways. Thor would probably be a bit confused as he was used to Stark's quick - witted remarks during battles.
Peter would probably be really confused at first. He looks up to Tony, and suddenly being kidnapped by him would be a huge shock. He might try to talk to Tony, asking him why he's doing this.
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.
They might be in shock. Tony has a complex past, and seeing it all unfold could leave them speechless.
Well, she could have a mentor - mentee relationship with Bruce Banner. He could help her with the scientific aspects of her father's work. And she might be a bit scared of Hulk at first but then realize that he's just as much a part of the team as the others. With Hawkeye, she could learn about precision and focus in combat. Also, she could bring a new dynamic to the group, being the younger and more inexperienced one, but also having fresh ideas and a different perspective based on her unique upbringing as Tony Stark's daughter.
Well, there are several common themes. Resistance is one. Tony Stark is a strong - willed character, and in these fanfictions, he usually resists Hydra's attempts to take over or manipulate him. Also, the exploration of power is common. How Hydra wants to use Stark's power, and how he uses his power to fight back. And secrecy, as Hydra operates in the shadows and Stark has to uncover their plots.