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.
Well, a plot could involve a cross - over of the two worlds due to some sort of magical or scientific accident. The vampires from Vampire Knight might be intrigued by the ghouls' abilities in Tokyo Ghoul. And the ghouls could be both fascinated and scared of the vampires' elegance and power. There could be a fight for control over a new source of 'food' that emerges from this cross - over situation.
The plot could center around a love story between a character from Tokyo Ghoul and one from Vampire Knight. For example, a ghoul girl falling in love with a vampire boy. They would have to face the prejudices of both their worlds. The ghouls would be against her being with a vampire as they see them as a threat, and the vampires would also oppose it because of the ghoul's nature. Their love could be the key to bringing some sort of peace between the two warring species in the fanfiction.
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.
The plot might focus on the struggle for identity that both Kaneki and Shinichi face. Kaneki is caught between his human and ghoul sides, while Shinichi has to deal with having a parasite in him. In the crossover fanfic, they could exchange their experiences and learn from each other. They might also encounter a new type of being that combines the traits of ghouls and parasites, which forces them to re - evaluate their own identities and how they fit into this new world of the crossover.
The plot could involve the ghouls from Tokyo Ghoul being brought into the Avengers' world. Maybe the Avengers initially mistake the ghouls for new, dangerous threats. But as they learn more about the ghouls' situation, they might try to find a way to co - exist. For example, Kaneki could share his story with the Avengers, and they could be sympathetic. Then they could team up to fight a common enemy, like a new type of super - villain who wants to use the power of ghouls for evil purposes.
Well, it could start with a strange portal opening up that transports some of the Tokyo Ghoul characters into the Devilman's world or vice versa. At first, there would be confusion and mistrust. But as they start to understand each other's situations, they realize that they need to work together. The story could then explore how their different powers interact. Like, how would the CCG's quinque weapons fare against Devilman's foes? And how would the Devilman's allies react to the existence of ghouls?
The storyline could be really interesting. Maybe the ghouls could be a new kind of dark creature in the Harry Potter world. The characters from Tokyo Ghoul, like Ken Kaneki, might attend Hogwarts. He could struggle with his ghoul nature while trying to fit in with the wizards and witches. The magic in the Harry Potter universe could also have an impact on the ghouls' abilities, perhaps suppressing or enhancing them.
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.
A crossover story could be really exciting. In this kind of fanfiction, we might see the Survey Corps from Attack on Titan having to deal with the ghouls from Tokyo Ghoul. Maybe Eren and his friends would be confused at first about these new, strange creatures that are part human, part something else. They could initially mistake the ghouls for Titans. And the ghouls, on the other hand, would be equally shocked by the Titans and the advanced technology the Attack on Titan characters use. It would be a clash of two very different but equally dark and violent worlds.
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 possible plot could be that Uta, with his unique mask - making skills from Tokyo Ghoul, gets involved in a situation where he has to create a special mask for a character from the Uta no Prince - sama world. Maybe this mask gives the Uta no Prince - sama character some special powers related to the ghoul world, like enhanced hearing or the ability to see in the dark. And then they have to navigate through both the music - filled world of Uta no Prince - sama and the dangerous world of Tokyo Ghoul together.
Well, in a Tokyo Ghoul and Harry Potter crossover fanfiction, there could be a character who is both a ghoul and a wizard. This character would have to struggle with the dual nature of their existence. On one hand, they have the magic of the wizarding world, but on the other, they have the hunger for human flesh as a ghoul. They might use magic to try and control their ghoul instincts, like using a spell to suppress the urge to attack people.