Mysterio could also be a villain in this scenario. He could use his illusions to make the people of New York lose hope. Since Spider - Man has the Blue Lantern powers of hope, Mysterio would see him as a threat. He could create elaborate illusions that make it seem like the Blue Lanterns are a force of evil, causing chaos and making Spider - Man's job of spreading hope and protecting the city much more difficult.
One possible plot could be Spider - Man somehow getting his hands on a Blue Lantern ring. The Blue Lanterns are known for hope. So, Spider - Man might use the power of hope from the ring to inspire the people of New York more than ever. He could face villains like the Green Goblin or Doctor Octopus, and with the Blue Lantern powers, he'd not only fight them physically but also spread hope among the citizens, making them more resilient against the villains' threats.
The Green Goblin could be the villain. He could have developed a new type of pumpkin bomb that explodes with a force that seriously injures Spider Man. This would be in line with their long - standing rivalry in the Spider - Man universe.
How about a new villain created specifically for the fanfiction? A being made up of the combined negative energy from all the spider - verses. This entity could be called the 'Void - Spider' and it feeds on the chaos and destruction that often follows Spider - Man in his battles. It would be a very powerful and unique threat that the Spider - Men from different universes would have to face together.
Perhaps a new character, like a genetically - engineered super - soldier gone wrong. This villain could have super strength and agility similar to Spider - Man, but with a more aggressive and unpredictable nature. He might see Spider - Man as a rival and be determined to prove that he is the superior one in the city.
It could be a mad scientist who creates mutated creatures to cause chaos in the city.
Venom is also a strong candidate. In this fanfiction, he could be more powerful than ever. He might be infected with some sort of alien symbiote that gives him enhanced abilities. Venom could target Spider - Man because he wants to prove that he is the stronger one. And by attacking Spider - Man, he also draws the attention of the Avengers, which he sees as a challenge. He could start by attacking the city and luring Spider - Man and the Avengers into a trap.
The Nullifier. This villain has the power to nullify any superpower within a certain radius. He could be a really tough opponent for Spider Man alone as he can't rely on his super - strength or agility when close to the Nullifier.
Mysterio would be an interesting villain for this fanfiction. He could use the chaos of the Age of Ultron to create illusions that further disrupt the city and make it difficult for Spider - Man to tell what's real and what's not. He might also be able to trick the Avengers into believing false threats, causing internal strife within the team.
The Green Goblin could be a great main villain in a crossover. Imagine if he teams up with Doctor Doom from the Fantastic Four universe. Their combined evil intelligence and power would be a huge threat to Spider - Man and whoever he teams up with in the crossover.
It could be Doctor Doom. He might be seeking to take over multiple universes in a crossover. Spider Man stands in his way, and Doom, with his superior intellect and powerful magic, manages to defeat Spider Man. His death would then be a huge shock to other heroes in the crossover, like the Avengers or the Fantastic Four who then have to avenge him.