What are some interesting plot ideas for a Merlin and the Originals crossover fanfiction?

One idea could be a love triangle between a vampire from 'The Vampire Diaries' and two characters from 'The Originals'. For example, a young vampire falls in love with Klaus but also has a deep connection with Elijah. This could create a lot of tension and drama as the two brothers have their own complex relationship. Another plot could involve a powerful vampire from 'The Vampire Diaries' coming to New Orleans and challenging the power structure that the Originals have built. This would lead to battles and political intrigue within the supernatural community.

Maybe the Avengers need the help of the witches from 'The Originals' to reverse a spell that an enemy has cast on Earth. Klaus and Loki could have some interesting interactions as two complex anti - heroes. The witches could use their magic to enhance the Avengers' weapons or powers in unique ways.

One idea could be that Buffy and her friends are called to New Orleans because of some strange vampire activity that seems linked to the Originals. Maybe the First Evil from Buffy's world has some connection to an ancient threat in the Originals' world, and they have to team up to stop it.

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.

One idea could be that a powerful witch from 'The Originals' world accidentally opens a portal to the 'Supernatural' world. Sam and Dean Winchester are drawn through it and end up in New Orleans. There, they team up with the Mikaelson family to fight a common enemy, like an ancient and powerful demon that is causing chaos in both their worlds.

One idea could be to cross the characters with another popular supernatural show's characters. For example, bringing in some characters from 'Buffy the Vampire Slayer' and seeing how they interact with the originals. Maybe Buffy could team up with Klaus to fight a new, powerful enemy that threatens both their worlds.

One idea could be that Merlin, with his magic from the Arthurian world, meets Eragon in Alagaesia. Maybe Merlin helps Eragon to better understand and control his own magic, as Merlin has centuries of experience. He could teach Eragon about different forms of magic and how to use it more subtly.

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 Merlin uses his magic to help Harry Potter in his fight against Voldemort. Maybe Merlin's ancient magic knowledge gives Harry an edge in finding Horcruxes. Another could be that the characters from the two universes meet at Hogwarts, like Merlin being a special guest lecturer, sharing his experiences of magic in a different era.

One idea could be that Hermione, with her vast knowledge from the wizarding world of Harry Potter, travels through time or a magical portal and meets Merlin. She could help Merlin with some of his more complex magical problems using her unique spells and techniques from Hogwarts. Another plot could involve them teaming up to defeat a common enemy that threatens both their worlds, perhaps a dark magic user who has found a way to bridge the two universes.