Another plot could involve a love triangle between a Twilight character, an H2O character, and a new character created for the crossover. The mermaid's ability to transform into a human and the vampire's allure would add an interesting dynamic to the love story.
One idea could be that the mermaids from H2O meet the vampires in Twilight. Maybe they form an unlikely alliance to fight a common enemy, like a group of powerful witches. The mermaids could use their water powers and the vampires their super strength and speed.
One plot idea could be that Bella Swan, from Twilight, gets lost in Gotham City. Batman discovers her and at first suspects she's part of some new vampire plot in his city. But as he gets to know her, he realizes she's just a lost girl with her own set of supernatural problems. Another idea is that the Cullens move to Gotham for some reason. Edward and Batman cross paths and Edward's mind - reading ability both intrigues and annoys Batman. They could end up working together to stop a new breed of super - vampires that are terrorizing the city.
Well, a cool plot could be a love triangle between a Twilight character, a Naruto character, and another from their respective worlds. Say Bella is torn between Edward and Sasuke. Sasuke's brooding nature could be seen as similar to Edward's, but his ninja skills and different moral code would add an interesting dynamic. Also, the clans in Naruto could have some sort of connection to the vampire covens in Twilight, like they share a long - lost ancestor who had both ninja and vampire - like abilities.
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.
A plot could involve a Twilight vampire falling in love with a shadowhunter. The vampire has to deal with the shadowhunter world's rules about the supernatural, and the shadowhunter has to come to terms with loving a vampire, which goes against their training. This could lead to a lot of internal and external conflicts as they try to be together.
One idea could be that Naruto is somehow transported to the Twilight universe. He might mistake the vampires for some sort of new enemy ninjas. And the vampires could be intrigued by his strange powers. For example, his shadow clone jutsu could really puzzle them.
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.
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.
One idea could be a character from Vampire Academy ending up in the Twilight world and having to adapt to their different vampire rules. For example, Rose could find herself in Forks and be really confused by the Cullens' 'vegetarian' vampire lifestyle.
One idea could be that the vampires in Twilight are discovered by the wizarding world in Harry Potter. The wizards might be intrigued and cautious at the same time. They could study the vampires' immortality and special abilities, while the vampires might be interested in the magic that wizards possess.
One idea could be that Naruto, with his newfound immortality, somehow ends up in the Twilight universe. He might be mistaken for a new kind of vampire due to his enhanced abilities. Another plot could involve the Twilight characters learning ninja techniques from Naruto. For example, Bella could learn how to better protect herself using Naruto's shadow clone jutsu.
Perhaps in a Star Wars Twilight crossover fanfiction, the Force could be seen as a kind of super - power in the Twilight universe. A Jedi could come to train the Twilight characters in how to use this 'new' power. They would have to adapt their Jedi teachings to fit the different nature of the Twilight world, which has its own set of rules regarding vampires and werewolves.