What are some interesting plot ideas for a charmed supernatural crossover fanfiction?

One idea could be that the Winchesters find themselves in the Charmed universe while hunting a cross - dimensional demon. They team up with the Halliwell sisters to defeat it. The contrast between the two groups' hunting styles would make for great drama.

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 that the Charmed Ones and Buffy team up to fight a powerful demon that has the ability to move between their two worlds. They have to combine their unique magical powers and slaying skills to defeat it.

One idea could be that the Halliwell sisters somehow end up in Camelot. They could use their magic to help Merlin deal with a powerful dark sorcerer that even his magic can't handle alone. Maybe they teach him some new spells or ways to control his magic better.

One idea could be that the Halliwell sisters from Charmed visit Hogwarts. They could help the students learn some new types of magic that are more in line with their own brand of magic. For example, teaching them how to create protection spells that are more intuitive rather than formula - based like some Hogwarts spells.

Well, a cool plot could be that an ancient, powerful entity from the Supernatural world is awakened in Smallville. Clark discovers it while trying to protect the town. He realizes he can't handle it alone and contacts Bobby Singer through some means. Bobby then sends Sam and Dean to help. They initially have a hard time trusting Clark because of his superpowers, but soon realize they need his help. As they battle the entity, they discover it has ties to an old, forgotten lore that involves both the kryptonite on Earth and a powerful demon they once fought. They have to combine their knowledge and powers to defeat it.

Perhaps there could be a crossover where the Endbringers in 'worm' are actually manifestations of some ancient supernatural evil. And a group of supernatural hunters from another dimension come to Brockton Bay to fight them, teaming up with local parahumans.

One idea could be that the Winchesters end up in Star City and team up with the Arrow to fight a demon that is using technology to cause chaos. Maybe the demon has possessed some of the tech - savvy villains in the Arrowverse.

One idea could be that the Winchesters are hunting a meta - human in Central City who has powers similar to a demon. The Flash team tries to stop them from killing the meta - human, thinking they are just bad guys. Another could be a time - travel situation where Barry accidentally travels to a world where the Supernatural events are real and has to team up with Sam and Dean to get back home. A third idea is that a powerful witch from the Supernatural universe uses her magic to create chaos in Central City, and the Flash and his friends need the help of the Winchesters to defeat her.

One interesting plot idea could be that the Flashpoint event somehow creates a rift that pulls characters from Supernatural into the Flashpoint universe. For example, Sam and Dean Winchester could be chasing a demon that escapes into this new, altered reality. They'd have to deal with the different laws of physics and the presence of superheroes like Flash. Another idea is that a powerful supernatural being from the Supernatural world causes the Flashpoint event in the first place, perhaps as part of a larger plan to reshape all of existence. And a third idea could be that a character from Flashpoint, like Iris West, has some latent supernatural ability that is awakened by the presence of the Winchester brothers, and they have to figure out how to control it before it causes chaos in both their worlds.