Well, one possibility is that the girl could be in danger from some villains. Tony Stark, being the hero he is, swoops in with his Iron Man suit. Maybe she's running from a group of bad guys who are after her for some secret she holds. Tony spots her while flying by and uses his repulsors to fend off the attackers, then takes her to safety.
It shows his heroic side even more. He's always ready to jump in and save someone in need, which is a big part of his character. Saving the girl running makes him seem more approachable and caring, not just a tech - genius billionaire in a suit.
At the start, Tony could be a bit skeptical of Harry's abilities. But when Harry shows off a spell, like making a Patronus, Tony would be impressed. They would then start to work together. Harry could use his magic to help Tony get into places that are otherwise inaccessible, and Tony could provide Harry with some cool gadgets. For example, Tony could give Harry a device that helps him communicate with the wizarding world more easily. They would learn from each other and form an unlikely friendship.
In a 'Percy Jackson Saves Tony Stark' fanfiction plot, Stark could be on a mission in a remote area that has some hidden mythological secrets. He unknowingly awakens an ancient evil. Percy Jackson, who is nearby on a quest of his own, notices the disturbance. He races to save Stark. Percy has to deal with his own personal demons as well as the new threat. He saves Stark by using his demigod powers in creative ways, like using the water in the environment to create shields or using his ability to read ancient languages to decipher a way to stop the evil. After that, they join forces to make sure the area is safe again and Stark is inspired by Percy's world to create new tech that can detect and deal with mythological threats.
One common theme is loyalty. Peter feels a deep loyalty towards Tony as his mentor and friend, and this drives him to save Tony in these stories. For example, in many fanfictions, Peter will risk his own life without hesitation when Tony is in danger.
One possible plot twist could be that Kraglin saves Tony, but it turns out Tony was set up as bait by a powerful enemy. So, instead of being out of danger, they are now both in the crosshairs of an even greater threat.
Often, the fanfictions involve Tony relying on his network of contacts. He might call in favors from other scientists or even some minor characters from the Marvel universe. There's also the aspect of him sacrificing something, like his own safety or his reputation, in order to save the Avengers. And of course, there are epic battle scenes where Tony uses his Iron Man tech to fight off the enemy and protect his teammates.
One popular 'Tony Stark saves the Avengers' fanfiction is 'Stark's Redemption'. In this fic, Tony uses his brilliant mind and advanced technology to rescue the Avengers from a powerful and mysterious enemy. He creates new gadgets on the fly and outsmarts the foe.
One great 'Peter Parker Saves Tony Stark' fanfiction is 'The Rescue'. In it, Peter uses his spider - sense and acrobatic skills to get Tony out of a dangerous situation involving a powerful enemy. The story really focuses on Peter's growth and his determination to save his mentor.
Well, one way could be through magic. Harry Potter has a whole arsenal of spells. He could use a protection spell to shield Tony Stark from an incoming attack. Maybe Iron Man's suit malfunctions during a battle, and Harry, being in the right place at the right time, uses 'Reparo' to fix it.