It could be that Supergirl, who has crossed over with The Flash, and Finn Hudson from Glee are the main characters. Supergirl's strength and Finn's leadership skills could combine to lead the group of Flash and Glee characters through some sort of crisis, like an alien invasion that affects both the world of superheroes and the high - school - like setting of Glee.
Cisco Ramon from The Flash and Kurt Hummel from Glee. Cisco could use his tech - savvy skills to create amazing stage effects for Kurt's performances. They might bond over their shared love for creativity and innovation, and their interactions could drive the plot forward as they try to bring the two groups of characters together for a big event.
Barry Allen from The Flash and Rachel Berry from Glee could be main characters. Barry's speed could be used in interesting ways, like helping Rachel get to auditions on time or saving her from some danger in the city. They could form an unlikely friendship and be at the center of the story.
Perhaps it's about a charity event where the actors who play the characters in The Flash and Glee come together for a reunion concert. The fanfiction could describe the behind - the - scenes preparations, the excitement of the fans, and the actual performance with a mix of Flash - themed stunts and Glee - like singing.
In a more complex scenario, the Glee characters could be transported to the Flash's city. There, they might use their musical talents to calm down an angry meta - human. Their singing could have a soothing effect on the meta - human's out - of - control powers, and the Flash would be amazed at this new way of handling threats.
Another option could be Puck. They had a bit of a history in the show. In the fanfiction, they could have reconnected in a moment of passion and now she's pregnant. This would surely stir up a lot of emotions among the other Glee club members, especially those who were close to both of them.
Team Rocket could also be the focus of a reunion fanfiction. Maybe they've reformed and are having a reunion to celebrate their new lives away from their villainous ways. They could be showing off their new Pokemon or skills that they've developed.
Well, maybe the characters from both shows would come together for a big musical event. They could perform some amazing mash - up songs. For example, Supergirl's heroic characters could join the Glee club on stage and sing some inspiring anthems together.
The children of Rachel and Finn could be main characters. Maybe their son or daughter inherits Rachel's amazing singing talent and Finn's charm. They could struggle with living up to their parents' legacy in the glee club.
Finn Hudson could also be a main character. He could be the one who has some initial reservations about the whole royal welcome thing but then slowly gets into the spirit of it as he sees how much it means to the other members of the Glee club.
Mr. Schuester from Glee could be a main character too. He could be the one who tries to bring the two groups together, seeing the potential in the Glee club and Supergirl working as a team. His role as a mentor in Glee could be extended to Supergirl as she tries to navigate the more complex aspects of human relationships and teamwork in this crossover fanfiction.
Kurt from Glee and Cisco from the Flash could also be a popular pairing. Kurt is known for his fashion sense and his sassy personality, and Cisco is the tech - genius of the Flash team. They could bond over their creativity, with Kurt helping Cisco with his style and Cisco introducing Kurt to some cool tech gadgets.
Another possibility is that it could involve a new character created specifically for this fanfiction. This character could be a hybrid of Twilight - like abilities and some form of super - speed, and they could be the one sharing the kiss with either a well - known Twilight character or a Flash character.