One plot idea could be that the vampires from Twilight possess some of the superpowers from the Marvel universe. For example, Edward could have Wolverine's healing factor in addition to his vampire abilities. This would make him even more indestructible and add a new layer to his character.
Maybe the Cullens find themselves in a world where they have to team up with the Avengers. The Avengers are initially suspicious of them, but they soon realize that the Cullens' abilities can be useful in fighting a common enemy. The Cullens, on the other hand, are in awe of the high - tech gadgets and the different superpowers the Avengers have.
One idea could be Gohan getting transported to the Marvel universe and teaming up with the Avengers. He could use his Saiyan powers to help them fight against Thanos. Maybe his energy blasts would be a new weapon against the powerful foes in the Marvel world.
One idea could be Sans from Undertale ending up in the Marvel universe. He could use his shortcuts and bone attacks to fight alongside the Avengers against a common enemy like Thanos. His laid - back attitude would contrast with the more serious heroes in Marvel.
One idea could be that Superman gets transported to the Marvel universe during a freak interdimensional event. He teams up with the Avengers to fight a common enemy like Thanos, who has somehow obtained Kryptonite. Their combined powers and different strategies would make for an epic battle and an interesting exploration of how the two universes' heroes interact.
Maybe in the fanfiction, Cortana could be integrated into Iron Man's suit. Her advanced AI could enhance the suit's capabilities even further. And they could work together to take on a new villain that is causing chaos in both the Halo and Marvel worlds. It would be a great mix of science - fiction elements from both universes.
One idea could be that Ben Tennyson's Omnitrix gets mixed up with some of the Infinity Stones' energy. This causes his aliens to gain new powers related to the Stones. For example, Four Arms could have super strength on a whole new level like Hulk. Another plot could be that the heroes from both universes have to team up to fight a villain who is using technology from the Ben 10 world and magic from the Marvel universe. Maybe a new character who has stolen some of Doctor Doom's knowledge and some of Vilgax's power.
One plot idea could be Naruto being transported to the Marvel Universe during a strange space - time rift. He might team up with Spider - Man. Naruto's ninja skills like shadow clones and rasengan could be a great asset in battles against Marvel villains. Another idea is that the Infinity Stones somehow end up in the Naruto world, and the Avengers have to go there to retrieve them, leading to a clash and then an alliance between the two groups.
One idea could be that the Infinity Stones are somehow connected to the Warp in the Warhammer universe. Maybe Thanos discovers a way to tap into the power of the Warp through the Stones, which brings the heroes of Marvel into conflict with the daemons and factions of Warhammer.
A fun plot could involve the Marvel heroes visiting the Soul Society. Captain America might be intrigued by the strict hierarchical structure and the sense of honor among the Soul Reapers. Meanwhile, Spider - Man could get into all sorts of trouble exploring the different districts of the Soul Society, and his quick - wittedness would be put to the test when dealing with the various spirits and Soul Reapers.
Perhaps a spell gone wrong in the Charmed universe causes a portal to open to the Twilight world. The Charmed Ones end up in Forks and meet the Cullens. They initially suspect the Cullens of being dark magic users but then realize they are vampires. Together they face a common enemy that is drawn to the combined magic and vampire allure in the area.
A really cool plot for this crossover fanfiction could be that there is a prophecy in both the Twilight and The Originals worlds. It predicts that a certain character from each universe must join forces to save both worlds from a great evil. This could be a dark force that is slowly consuming all supernatural beings. Bella Swan could be the key in the Twilight world, and Hope Mikaelson in The Originals world. As they meet and start to work together, they face many challenges due to the different beliefs and power systems in their respective worlds. Their friends and families from both sides also get involved, creating a complex web of relationships and power struggles.