Well, here's an idea. The Avengers are investigating strange disappearances in a small town which is actually the hunting ground of a rogue vampire. The Cullens get involved because they don't want the vampire to expose their kind. So they team up with the Avengers. In the process, Thor discovers that there are some similarities between the magic in his world and the vampire abilities. This leads to an exchange of knowledge between the two groups. And Black Widow could use her skills to train the Cullens in combat techniques they don't know.
A plot could be that the Twilight vampires are mistaken for a new threat by the Avengers. So, there's a lot of misunderstanding and conflict at first. But then they realize that there is a real bad guy who is using their feud to his advantage. They then have to work together to take this villain down. Also, what if some of the Avengers become vampires or werewolves? How would that change their dynamic and abilities? For instance, if Captain America became a vampire, would his sense of justice remain the same? And how would his new powers interact with his old ones?
One interesting plot idea could be exploring how different characters adapt to the post - apocalyptic world in new and unexpected ways. For example, a character who was once a timid office worker becomes a fearless scavenger.
A really cool plot idea could be that the Avengers are watching Endgame in a sort of 'alternate reality cinema' where the events in the movie start to bleed into their real world. So they have to stop the movie from fully playing out to prevent chaos in their own universe. This would involve a lot of action and strategic thinking as they try to stop things like Thanos from emerging from the screen while also trying to understand the significance of what they're seeing in the movie.
One idea could be that the mutants and the Avengers have to team up against a common enemy that is immune to their individual powers. So they must learn to combine their abilities in new ways. For example, Wolverine's healing factor could be used to keep an injured Avenger alive during a long battle while Iron Man figures out a way to defeat the enemy.
One idea could be that Harry Potter is magically transported to the Avengers' universe. He could use his magic to help the Avengers in battles, like creating protective shields with spells. Another idea is that the Avengers are somehow sent to Hogwarts, and they have to learn about magic while also dealing with threats in the wizarding world. For example, Iron Man might try to figure out how to integrate his technology with magic.
One idea could be exploring the family dynamics when the Avengers have to take care of a young superhero in training. It would be fun to see how they each contribute to the kid's growth, like Tony Stark teaching about technology and Captain America instilling values.
One idea could be the Avengers facing off against a new, powerful villain who has the ability to turn their own powers against them. This would lead to some really intense battles and strategic thinking on the Avengers' part.
One idea could be that the adopted character has a special power that the Avengers initially don't understand. This power could be something like the ability to communicate with animals, which helps them during a mission where they need to track a villain through a forest. Another could be that the character has a connection to an ancient artifact that the Avengers are also interested in for some reason, and this connection leads to a series of adventures.
One idea could be the Avengers facing off against a new, unjust system within their own superhero community. Maybe some heroes are being wrongly persecuted due to false accusations of using their powers for personal gain. This would create a lot of internal conflict as they try to clear their names and fight against the system.
One idea could be exploring the Next Avengers facing a new, powerful villain from another dimension. This villain could have unique powers that the young heroes have never encountered before, forcing them to quickly adapt and learn new strategies.
One idea could be that Kratos is somehow transported to the Avengers' universe. He initially clashes with them due to his different methods and values. For example, Thor might see Kratos as a rival in strength. But eventually, they team up to fight a common enemy like Thanos who has somehow gained the power of the Greek gods. Kratos could teach the Avengers about his brutal combat style and his knowledge of ancient magic.