I think Caroline Forbes could be an interesting character to focus on. She's from 'The Vampire Diaries' which is related to 'The Originals'. If she were to be part of a 'The Originals' and 'Supernatural' crossover, she could bridge the gap between the two worlds. She's a strong - willed vampire who has learned to adapt and grow. Her positive attitude could contrast with the more brooding nature of some of the 'Supernatural' characters, and she could bring a fresh perspective to the team - up against whatever supernatural threat they face.
Definitely Damon Salvatore. He's the bad - boy vampire with a heart of gold (sometimes). In a crossover, he'd be a wild card. He has his own sense of justice and loyalty, but also a devil - may - care attitude. He could get into all sorts of trouble in the world of the Originals. His sarcastic remarks and his ability to charm his way out of (or into) situations would make for some great scenes. He might also form an unlikely friendship or rivalry with one of the Originals, like Kol perhaps. His backstory and his experiences in 'The Vampire Diaries' would contrast and collide in interesting ways with the Originals' world.
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.
Klaus and Merlin would be a very interesting pairing. Klaus is a complex and often villainous character in the Originals, while Merlin is a hero in his own story. Their clash of personalities and power dynamics would be fascinating. Merlin's moral compass could be a challenge to Klaus' more self - serving ways.
Willow from Buffy's world and Davina from the Originals could make for an exciting pairing. Willow is a powerful witch, and Davina is also very talented in magic. They could exchange spells and knowledge, and maybe even create new magic together to fight a common enemy.
Elijah Mikaelson is also a great choice. He is the more level - headed and noble of the Mikaelson siblings. In a crossover, he could be the diplomat or the voice of reason, interacting with characters who might be more impulsive or have different moral compasses. For example, if crossed with characters from 'Teen Wolf', he could offer a different perspective on the werewolf lore.
Original crossover fanfiction is a type of fan - created work that combines elements from two or more different original works. For example, it might blend characters from 'Harry Potter' and 'The Lord of the Rings' in a new story. Fans write these to explore new scenarios, relationships, and adventures that wouldn't exist in the original works alone.
I think Rose and Klaus would be an interesting pairing. Rose is a tough and feisty guardian from Vampire Academy, and Klaus is a powerful and complex original vampire. Their interactions would be full of sparks, as they both have strong personalities and a lot of power. They could either be at odds with each other or end up having an unexpected alliance.
Arya Stark and Rebekah Mikaelson. Arya is a trained assassin, and Rebekah is a fierce vampire. They could learn a lot from each other. Arya could teach Rebekah some of her stealth and combat skills without the use of vampire powers, and Rebekah could introduce Arya to the world of the supernatural and its different rules of survival.
Chiaki Nanami could be an excellent choice. She is the Ultimate Gamer, so if you cross her with a digital or virtual world, there are so many possibilities. She could use her gaming skills to navigate through a new digital realm, like a Matrix - like world. Her calm and intelligent nature would also make her a great character to lead the group in a crossover situation. She could figure out the rules of the new world quickly and help the others adapt.
Ross could be really interesting. Since he's an archaeologist, in a crossover with a show like 'Indiana Jones' (in a fanfiction sense), he could go on an adventure with Indiana Jones. Ross would bring his academic knowledge while Indy would have the practical experience. Their interactions would be filled with Ross trying to over - analyze everything and Indy just wanting to get the job done.