Who could be the main villain in an 'Avengers meet Spiderman' fanfic?

It could be Mysterio. He's a master of illusions. He might trick the Avengers into believing that Spiderman is a danger, using his illusions to make it seem like Spiderman is doing bad things. So the Avengers, thinking they're doing the right thing, kidnap Spiderman.

Well, in such a fanfic, the Avengers could initially be skeptical of Spiderman. Maybe they think he's too young and inexperienced. But then Spiderman could prove himself by using his unique web - slinging skills to save one of the Avengers from a tricky situation. And they start to see his potential and welcome him to the team.

Maybe a biologist gone bad. He has been studying the worm and discovers that its cells can be used to create a powerful mutagen that can turn ordinary people into super - strong minions. He plans to create an army and take over the city. Spiderman has to stop him from using the worm in this way. And the worm, being an innocent creature, becomes a key piece in this battle between good and evil.

It could be a mad scientist. He could have been studying the Avengers from afar in their own universe and when they arrive in our world, he sees an opportunity. He might try to steal their powers or technology to create his own super - army.

Thor could be the main character. Since he has a connection to Norse mythology and Sleipnir is from that realm. He would be the one most likely to understand Sleipnir and communicate with it.

Doctor Octopus would also work well. He could use his mechanical arms to manipulate the game environment and create deadly traps for Spiderman, all while trying to steal some valuable in - game technology.

The three Avengers could be Iron Man, Captain America and Thor. Iron Man could provide the high - tech gadgets and strategic thinking. Captain America would bring leadership and his combat skills. Thor with his godly powers like lightning and super strength would be a great addition. They would each have different interactions with Spiderman, for example, Iron Man might be like a mentor to him, while Thor could be more of a friendly rival in terms of strength.

A powerful necromancer could be a great main villain. He tries to control the ghostly avengers for his own evil purposes, using dark magic to manipulate them.

The Green Goblin could be a great main villain. He could be working on a plan that not only threatens Spider - Man's world but also the areas the Defenders protect. His maniacal nature and flying abilities would pose a great challenge to both Spider - Man's acrobatics and the Defenders' combat skills.

Thanos could still be a likely villain. Even if he was defeated in the official storyline, in a fanfic he could return more powerful or with a new plan. His obsession with the Infinity Stones makes him a great overarching threat.