Another idea is a crossover with a historical setting, say the Roman Empire. The Queen's Blade characters would be transported back in time. Their presence could disrupt the power balance in the Roman Empire. Some might be seen as powerful gladiators, while others could use their charm and wits to influence the politics of the time. This would create a whole new dynamic and many potential storylines.
One idea could be a crossover with a fantasy RPG world. The Queen's Blade characters could find themselves in a world full of magic spells and mythical creatures from the RPG. They might have to adapt their fighting styles and skills to survive in this new environment. For example, Leina could form an alliance with the mages in the RPG world to fight against a common enemy that threatens both their lands.
Another plot idea is a crossover with a post - apocalyptic world. The Queen's Blade warriors are transported to a desolate future where resources are scarce. They would have to use their combat prowess to survive against gangs of raiders and also figure out how to get back to their own world. This would put their skills and survival instincts to the test.
Well, for Blade and Soul crossover fanfiction, you could consider a crossover with a post - apocalyptic world. The Blade and Soul characters' combat skills would be very useful in a world full of mutants and raiders. They could either be trying to find a way to restore the world or just survive. Or perhaps a crossover with a magical girl anime world. It would be interesting to see how the serious and martial - arts - focused Blade and Soul characters interact with the cutesy and magical elements of a magical girl world. And also, a crossover with a space - opera setting. The characters could be part of a galactic war or exploration mission, using their unique skills in a whole new environment.
One idea could be a crossover with another Kamen Rider series like Kamen Rider Decade. Blade could find himself in Decade's world, where he has to team up with Decade to fight a common enemy that threatens both their worlds. This would bring a lot of action and an interesting dynamic between the two different Kamen Riders.
One idea could be that Blade, with his vampire - hunting skills, enters the wizarding world. He could mistake some of the vampires in the Harry Potter universe, like the ones associated with Sanguini, for normal vampires and start hunting them. This would cause chaos as the wizards don't understand his motives at first.
Well, a cool 'unlimited blade works crossover fanfiction' idea might involve crossing it with a sci - fi setting. For example, Shirou finds himself on a spaceship and has to use Unlimited Blade Works against alien threats. It could also be interesting to cross it with a historical - fiction world, like the samurai - era Japan. He could have duels with famous samurai using his blade - creating ability. And then there's the idea of crossing it with a magical girl universe. His serious and practical magic would be an interesting contrast to the more flamboyant magic of magical girls.
One idea could be to cross it with a vampire hunter story. The 'queen of the damned' could be the main target of a group of vampire hunters from another franchise. This would create a lot of conflict and action scenes.
One interesting Queen's Blade fanfic could be about a new character joining the tournament. This new character might have a unique backstory and special abilities that change the dynamics of the battles.
One idea could be that Naruto is transported to the Mortal Kombat universe where he meets Sonya Blade. They could team up to fight against a common enemy, perhaps a powerful ninja from Naruto's world who has also ended up in Mortal Kombat. Naruto's unique jutsu skills combined with Sonya Blade's combat expertise would make for an interesting dynamic.
I think Leina would be a great choice. She has a strong sense of justice and is always looking to improve herself. In a crossover, she could be the one to bridge the gap between different groups or worlds. For instance, if crossed over with a space - faring civilization, she might be the first to try and understand their technology and culture, while also showing them the values of her own world.
One idea could be exploring the backstory of the new replicants. Maybe a fanfiction about how they were created and what their initial experiences were like before entering society in 2049.