Well, a cool plot could be that there's a scientific experiment gone wrong that fuses Venom and Spider - Man's powers in an unexpected way. They have to figure out how to control these new combined abilities while also dealing with villains who want to steal their power source. Or perhaps Venom gets amnesia and Spider - Man has to convince him that they were once enemies but now need to work together. There could also be a story where Venom's offspring has a different relationship with Spider - Man, like it's more of an anti - hero sidekick.
One idea could be Venom and Spider - Man teaming up against a new, more powerful symbiote that threatens the city. They have to put aside their differences and use their combined powers to defeat it.
One idea could be that the OC has a special power that can either enhance or counteract Venom's abilities. For example, the OC might be able to emit a frequency that calms Venom when he's in a rage. Another plot could involve the OC being from a different dimension and getting stuck in Spider - Man's world, and Venom takes an immediate interest in this strange new being. They could start as enemies but gradually form an alliance as they face common threats.
Another interesting plot could be that a mad scientist creates a device that can separate Venom from his host. However, the separation goes wrong and the symbiote energy starts to spread across the city, infecting people. Spider - Man and Venom must work together to find a way to contain the energy and save the city.
Well, a cool Venom and Spider - Man crossover fanfiction idea might be that there's a strange alien invasion. But this time, the symbiotes are being controlled by an even greater evil. Venom, having his own sense of justice, decides to work with Spider - Man. They start off not trusting each other much, but as they face the challenges, they learn to rely on one another. Also, perhaps Spider - Man has to deal with some of Venom's more violent tendencies during the fight.
One idea could be Agent Venom having to team up with Spider - Man to take on a new super - villain who has the ability to control technology. They start off distrusting each other because of their different methods, but as the story progresses, they learn to work together. Another plot could involve Agent Venom getting infected with a virus that makes him turn on Spider - Man, and Spider - Man has to find a cure while fighting off Agent Venom's attacks. A third idea is that they both discover a secret conspiracy within the superhero community that they have to expose together.
Perhaps in a fanfiction, Venom is actually a creation of one of the villains in Homecoming who wants to use it to defeat Spider - Man. But the symbiote has a mind of its own and instead starts to have an odd connection with Spider - Man, leading to a complex relationship where they have to figure out if they can trust each other.
One interesting storyline could be Venom teaming up with Spider - Man in a Homecoming - based setting. Maybe there's a new threat in the city that they both realize they need to face together. For example, a powerful criminal organization that's using advanced technology stolen from Stark Industries. Another could be a Venom - origin story set during the time frame of Homecoming, where the symbiote's arrival on Earth and its connection to Peter Parker's world is explored in a different way than in the official comics or movies.
One idea could be exploring the different Spider - People's home universes in more detail. For example, showing what Miles Morales' daily life in his universe was like before becoming Spider - Man. Another could be a team - up between Miles and an older, more experienced Spider - Person from a different universe to face a new and powerful villain.
Perhaps there's a fanfiction where Spider Man and Spider Gwen accidentally swap powers. They have to learn how to use each other's abilities to fight crime. This would lead to some really funny and also challenging situations as they get used to different ways of web - slinging and sensing danger.
One interesting plot twist could be that Venom starts to have memories of Peter Parker's life as Spider - Man. This would create a strange dynamic where Venom understands Spider - Man's motives on a deeper level and might even start to protect the things Spider - Man cares about. For example, Venom could find itself saving Mary Jane from a random mugger because it has a new - found sense of connection to Spider - Man's world.