A great plot could be that the Avengers are facing a powerful enemy that can manipulate time. Spider - Man, with his spider - sense, is somehow immune to the time - altering effects. So, he has to lead the Avengers through different time periods to gather the necessary elements to defeat this enemy. This would involve lots of character development as the Avengers learn from different versions of themselves in the past and future.
Maybe in the fanfiction, Spider - Man discovers a secret connection between his powers and an ancient Asgardian artifact. The Avengers, especially Thor, would be intrigued. They then embark on a journey to figure out how this connection could either save or endanger the world. Spider - Man would have to balance his normal life and this new discovery with the Avengers.
Maybe Spider - Man discovers a new threat that the Avengers have overlooked. He then tries to convince them of the danger, facing skepticism at first but eventually winning them over with his tenacity and evidence. For example, he could find a hidden group of villains planning to use a new type of technology to take over the world.
A great plot for Amazing Spider - Man fanfiction could be a time - travel story. Spider - Man could be sent back in time to the era when his powers first emerged. He could then use his knowledge of the future to prevent some of the tragedies that occurred in his past, like the death of Uncle Ben. Or, he could be sent to a future where New York has become a dystopia, and he has to find a way to fix it and return to his own time.
One idea could be Spider - Man joining the Avengers on a mission to a far - off planet. He uses his agility and quick thinking to help the team out of tricky situations. Another could be a story where Spider - Man has to prove himself to the Avengers in a training exercise set up by Iron Man.
One possible plot could be that Spider - Man gets accidentally transported to the Avengers' headquarters. He has to prove himself to the Avengers at first, since they don't really know him well. Then, they discover a common enemy that is planning to attack both New York City (Spider - Man's territory) and other major cities around the world that the Avengers protect. Together, they combine their powers and skills. Spider - Man's agility and spider - sense work well with Iron Man's technology, Captain America's leadership and combat skills, Thor's godly strength, etc. They have to overcome their differences in fighting styles and strategies to defeat the enemy.
One interesting crossover could be Spider - Man using his agility and web - slinging skills to help the Avengers in a city - based battle. His ability to move quickly through the skyscrapers can give the Avengers an edge in a fight against villains who are causing chaos in a metropolis.
One idea could be exploring a new villain that is created from a scientific experiment gone wrong in Oscorp. This villain could have powers related to electricity and pose a new threat to Spider - Man.
One plot idea could be that Gwen discovers a new superpower that she has to learn to control, and Peter helps her through the process. This could add a new dynamic to their relationship as they both have different powers and ways of handling them.
One idea could be that Spider - Man has to use his unique street - level skills to help the Avengers in a mission where they are facing a villain who can manipulate technology in a city. His agility and quick thinking can give the Avengers an edge in the narrow alleys and on top of skyscrapers.
One idea could be that Spider - Man uses his agility to outmaneuver an enemy that has the Avengers trapped. For example, he could swing in and steal a key device from the bad guys that's jamming the Avengers' powers.
A crossover with the Avengers is also great. Picture Spider - Man having to prove himself to the more established heroes like Iron Man and Captain America. He could bring his unique street - level hero skills to a big - scale Avengers mission.