The main antagonists could be the official Avengers themselves. Since Peter Parker has joined the rogue Avengers, the main Avengers group might see them as a threat to the order they are trying to maintain. They could try to stop the rogue Avengers from achieving their goals, which would put them in direct conflict with Peter and his new allies.
It could be some new supervillain or a powerful organization that the rogue Avengers are trying to oppose, but the official Avengers don't believe in their methods. So, while the rogue Avengers are fighting this real evil, the official Avengers are trying to stop them, making the official Avengers seem like antagonists from the rogue Avengers' perspective. And Peter has to deal with this complex situation where he has to choose between what he believes is right and his loyalty to the original Avengers.
Another possibility for the main antagonists in this fanfiction could be a secret group within the superhero community. This group could be pulling the strings behind the scenes, making the official Avengers act in a way that the rogue Avengers oppose. Peter and the rogue Avengers might discover this group's existence and try to expose them, but the official Avengers, who are being manipulated, end up trying to stop the rogue Avengers from getting to the truth.
Well, perhaps the plot could involve Peter Parker feeling disillusioned with the main Avengers group for some reason. Maybe he disagrees with their new leadership or a particular decision they made. So, he decides to join the rogue Avengers. They might be on a mission to expose some hidden secrets within the superhero community that the official Avengers are trying to keep under wraps. And Peter, with his unique abilities and sense of justice, could play a crucial role in their operations.
If Peter Parker joins the Avengers in fanfiction, it would change the team dynamics significantly. Peter is used to operating on his own in Queens, but with the Avengers, he'd have to learn to work as part of a much larger and more powerful team. He could introduce the Avengers to his street - level knowledge, which might be useful when dealing with villains who operate in the shadows. His relationship with Aunt May could also play a role, as the Avengers might need to protect her from any potential threats. Plus, his growth as a hero would be accelerated by being around such experienced and powerful teammates.
In this fanfiction, Peter Parker might initially be in awe of the Rogue Avengers. He could try to prove himself to them, showing off his Spidey skills. Maybe they start off distrusting him, seeing him as just a kid, but as they face challenges together, they come to respect his abilities and his big heart.
Well, in such a fanfiction, the Rogue Avengers might initially be suspicious of Peter Parker. They could mistake him for an enemy or a spy at first. But then, as they get to know him, they might see his potential and start to train him in their own unique ways. Maybe they'll share their different experiences from being on the run, which could be really eye - opening for Peter.
The Green Goblin could be a main antagonist. He's known for causing chaos in New York City, and a building collapse would be right up his alley. He could be targeting the building for some strategic reason, like trying to get to Peter Parker or to create general mayhem.
Maybe it's a group of intergalactic criminals who are after the power that Peter Parker has as a 'child of the universe'. They could be stealing artifacts from different planets to gain more power and they see Peter as the ultimate source of power that they need to complete their collection.
The Green Goblin could be a main antagonist. He might see Peter's control of Alchemax as a threat to his own criminal empire and try to take over the company or destroy it. Another could be Doctor Octopus. With his brilliant mind, he may want to use Alchemax's resources for his own mad experiments.
There's a possibility that it's an old enemy of the Avengers who sees this as an opportunity. For example, Hydra could be involved. They might try to manipulate the situation to bring down both the rogue avengers and Peter Parker. They could spread false information to make the public turn against them all, while they carry out their own evil plans in the shadows.
Probably Steve Rogers. He has that all - American hero charm and he values loyalty and courage, which Peter clearly has. Steve would recognize those qualities in Peter right away and would want to get to know him better. He might see Peter as a symbol of the future of heroism and be eager to befriend him.
In a 'rogue avengers meet peter parker fanfic', there could be a lot of interesting scenarios. Maybe the rogue avengers need Peter's help for a secret mission. They might initially be skeptical of the young hero but soon realize his potential.