Well, first of all, the Avengers would need to locate Harry Potter. Maybe Hawkeye could use his eagle - eyed skills to spot him. Then, Captain America could lead the team in a rescue mission. Hulk could be the muscle, smashing through any obstacles in their way. Black Widow could use her combat skills to take out any enemies nearby. And finally, they could use the Quinjet to escape with Harry to safety.
In some fanfictions, Neville could play a crucial role in rescuing Harry. Neville has grown a lot throughout the series and could surprise everyone with his courage and newfound magical abilities. There could also be some unexpected allies, like a group of centaurs or house - elves who decide to help because they recognize the importance of Harry in the fight against Voldemort. House - elves, for example, are known for their powerful magic that is often underestimated, and they could use it to their advantage to free Harry.
One interesting plotline could be Harry using a new and powerful spell he discovers to rescue his friends from a dark wizard's lair. He might face many obstacles along the way, like magical traps and enchanted creatures.
In some fanfictions, Snape might rescue Harry Potter by using his knowledge of the Dark Arts to counter a dark spell aimed at Harry. For example, if Voldemort or his Death Eaters were about to cast a fatal curse on Harry, Snape could step in and deflect it with a powerful counter - curse. He is a very skilled wizard, after all.
Dumbledore could rescue Harry. He's always been watching over Harry and would surely sense if the Dursleys had abandoned him. Dumbledore has the power and wisdom to take Harry to a safe place, perhaps a different magical family or a special hideout. He could also start teaching Harry about his past and his parents earlier, which would give Harry a better understanding of his place in the wizarding world.
Sometimes, characters like Neville Longbottom can play a significant role. For example, he could be in a situation where Harry has to rescue him, but then Neville turns out to have some hidden knowledge or power that helps them in the end. And Dumbledore might also make an appearance in the background, guiding Harry in some way.
It could be Dumbledore. He has great power and knowledge. He might have some secret plan all along. He could use his influence and magic to enter Azkaban and free Harry, especially if he discovers that Harry is wrongly imprisoned.
Another theme is heroism. The rescuers often have to display great courage and use their unique skills to save Harry. It could be a combination of magical abilities and quick thinking. For instance, Neville might use his new - found confidence and knowledge of herbology to help in the rescue. Also, self - sacrifice is sometimes seen. Some characters may put themselves in harm's way to ensure Harry's safety.
In this kind of fanfiction, perhaps the goblins rescue Harry because they recognize his importance in the wizarding world. Maybe they see him as a key to some sort of financial or magical stability. For example, Harry might be in danger from Voldemort and his Death Eaters, and the goblins, who have their own interests and powers, decide to step in and save him. They could use their knowledge of Gringotts' secrets and their own combat skills to fight off the dark forces.
Hermione could be one to rescue Harry. She might have discovered some new spell or potion that allows her to bypass the protections around the Dursleys' house and get to Harry. Then she'd use her intelligence and quick thinking to get him out of there safely.