Another plot could involve some of the Avengers getting lost in Star City (from Arrow). They have to work with the Arrow team to find their way back to their own universe. Along the way, they share their skills and knowledge. For example, Hawkeye could teach some of the Arrow team members new archery techniques, while Oliver could show the Avengers how to be more stealthy in urban environments.
A possible plot could be that Oliver Queen from Arrow gets transported to the Marvel universe where the Avengers operate. He might initially be seen as a threat, but then he teams up with the Avengers to fight a common enemy. Maybe a villain that has powers related to both the technology in Arrow and the superpowers in the Avengers' world.
One possible plot could be that Oliver Queen gets transported to the Avengers' universe. He teams up with Hawkeye, sharing their archery skills and combat tactics. They could go on a mission to stop a new threat that combines the technology of the Arrowverse and the super - powered enemies of the Avengers.
One possible plot could be that the Avengers are somehow transported to the Arrow's universe. Maybe a villain in the Arrowverse has acquired a powerful artifact that creates portals, accidentally pulling in the Avengers. Then, they team up with Arrow and his team to fight against a common enemy, like a new super - powered threat that neither group could handle alone.
The plot might involve a villain who has the ability to manipulate time or space. This causes disruptions in both the Marvel Universe and Green Arrow's world. The Avengers, with their superhuman powers and high - tech gadgets, and Green Arrow, with his street - smart skills and archery expertise, must find a way to stop this villain. They might have to travel between their respective universes, which could lead to some really interesting cultural clashes and misunderstandings.
You can start by looking on fanfiction platforms like Archive of Our Own (AO3) or FanFiction.net. These sites have a large collection of fanfictions. Just search for 'Arrow and Avengers crossover' and you'll get a list of relevant stories. Some might be really good, while others may not be to your taste. It's all about exploring and finding the ones that resonate with you.
Maybe it could be a time - traveling criminal. This villain has the ability to jump between different timelines and has noticed that by disrupting the key events in both the Arrow and Avengers universes, he can create chaos and then rule over the resulting mess. He would constantly be one step ahead of the heroes as he could manipulate time to his advantage. He could also use his knowledge of future events to set traps for the Avengers and the Arrow team.
Well, one possibility could be that Daredevil and Arrow find themselves in a common enemy situation. Maybe a powerful crime syndicate that operates in both their cities. They start off as strangers but soon realize they can help each other. They could combine their skills, Daredevil's enhanced senses and martial arts with Arrow's archery and parkour skills. And they'd have to learn to trust each other's methods which could lead to some interesting character moments.
In a Riverdale and Arrow crossover fanfiction, the story could start with some sort of interdimensional rift that pulls characters from both shows into one world. Riverdale characters would be shocked by the violence and danger in Arrow's world. Meanwhile, Arrow characters might find the high school drama and relationships in Riverdale quite strange. There could be a big bad villain that only the combined skills of both groups can defeat. They would have to learn to work together despite their differences, and along the way, there could be some romantic subplots between characters from the two shows as well.
Well, perhaps in this fanfiction, there's a multiverse rift that pulls Nightwing into the Avengers' world. The Avengers initially mistake him for an enemy, but after some misunderstandings are cleared up, they realize his skills. Together, they face a new threat created by a combination of Hydra and some of Nightwing's rogues gallery who have also crossed over. Nightwing could teach the Avengers some stealth tactics while they show him how to handle more powerful cosmic threats.
One possible plot could be that the Shikon Jewel gets scattered across the Marvel universe. Inuyasha and his friends, like Kagome, have to team up with the Avengers to retrieve the pieces. Iron Man might be intrigued by Inuyasha's sword and try to study it, while Captain America could admire Inuyasha's fighting spirit. They'd face villains who also want the power of the Shikon Jewel, creating an epic adventure.
One possible plot could be that the Voltron team gets transported to the Avengers' universe. They might initially be seen as threats, but then they realize they need to team up to fight a common enemy, like a powerful alien force that's too much for either group alone. The Voltron lions could combine in the middle of New York City, creating an amazing spectacle.