One possible plot could be a character from Tokyo Ghoul ending up in the world of Vampire Knight. Maybe Kaneki, with his unique ghoul powers, could interact with the vampires and hunters in Vampire Knight. He might initially be seen as a threat, but as the story progresses, they could find common ground in their struggle for survival in a world that fears them.
Kaneki and Zero could make an interesting pairing. Kaneki has his inner turmoil with his ghoul side, and Zero has his own battle against his vampire nature. They could bond over their struggles to control their 'dark' sides and their determination to protect the ones they care about.
Well, one way the storylines could blend is through the character interactions. In Tokyo Ghoul, the ghouls have a complex society and set of rules. In Rosario Vampire, there are various supernatural beings. If the two universes crossed over, perhaps the ghouls' need for human flesh could be in conflict with the vampires' need for blood in Rosario Vampire. Maybe some characters from each side would form alliances to deal with this new, complex situation.
Well, for a Tokyo Ghoul fan, reading fanfiction while being a fan of the original can be a mixed bag. On one hand, it's exciting to see how other fans' creativity expands the world. For example, there could be fanfictions that focus on the backstories of minor characters. However, sometimes the quality can vary. Some might not capture the essence of the Tokyo Ghoul world as well as others. But overall, it gives a chance to delve deeper into the fandom.
Power struggle is a common theme. You have the super - powered beings from Prototype and the ghouls from Tokyo Ghoul, all vying for control or survival in a merged world.
Some fanfictions crossover Tokyo Ghoul with Naruto. The idea of ninjas and ghouls in the same universe is really cool. The shinobi could be trying to hunt down the ghouls, or there could be some sort of alliance formed between certain ghouls and ninja clans. It offers a lot of potential for action - packed and character - driven stories.
The plot could involve a shared threat that forces the Tokyo Ghoul and Parasyte universes to collide. Maybe a new type of organism emerges that is even more dangerous than ghouls or parasites. The characters would then have to combine their unique abilities to combat this threat. For instance, Kaneki's kagune and Shinichi's enhanced physical abilities with his parasite Migi could be used in tandem. This would create an interesting dynamic as they try to figure out how to work together while also dealing with their own internal struggles related to their inhuman natures.
One great Tokyo Ghoul Kaneki crossover fanfiction is the one where he crosses over with the world of 'Attack on Titan'. It's really interesting to see how Kaneki's ghoul abilities interact with the Titans. The author does a great job of creating a believable scenario where the two worlds collide.
A new character could be a hybrid of a ghoul and a vampire. This character might have the strength and speed of both species. They could struggle with their dual nature, being attracted to both human blood and flesh but also having a sense of morality from both the ghoul and vampire worlds.