If we consider the interactions, Yuki Sohma and Ciel could have a rather complex relationship. Yuki is used to hiding his true self because of the curse, and Ciel is constantly putting on a front to maintain his power and authority. They might initially clash as they both try to figure each other out. Meanwhile, Sebastian could be amused by the different personalities in the Sohma family, like Kyo's hot - tempered nature, which is so different from the usually - stoic servants in the Phantomhive household. And Tohru could try to ease the tension between the two groups by her gentle nature and her ability to understand others' pain.
The characters would have some really interesting interactions. For example, Sebastian would likely be polite yet calculating when dealing with the Sohma family. He might see them as an interesting study, especially those with the animal curse. Tohru, being her kind self, would probably try to befriend Ciel and the others. However, Ciel might be initially suspicious of her overly - nice demeanor, as he's used to a world full of deception.
A possible plot could involve the characters from both series swapping their worlds. So, the Fruits Basket characters end up in the Victorian - era setting of Black Butler. Tohru Honda might be mistaken for a servant in the Phantomhive household. Her kind nature could either be a source of confusion or a way to bring some warmth to the often - dark and brooding environment. And Sebastian might be intrigued by the Sohma curse, seeing it as an interesting oddity in his long existence.
Inuyasha's sword, Tessaiga, could be used in interesting ways in the Fruits Basket world. For example, if a Sohma is in trouble during their transformation, Inuyasha could use Tessaiga to protect them. On the other hand, the Sohma's zodiac animal abilities could assist Inuyasha in his battles. Like Kyo's cat - like strength and agility could help Inuyasha in a fight against a particularly fast demon.
The interactions would also depend on the setting of the crossover. If it's set in the world of Black Butler, the Soul Eater characters would have to adapt to the Victorian - era society. Maka, for instance, might be frustrated by the strict social norms while trying to hunt for kishin eggs. The Black Butler characters would be in charge and would likely view the Soul Eater characters as outsiders at first. However, as they work together against common threats, they would start to understand and respect each other. If it's set in Soul Eater's Death City, the Black Butler characters would be in a more modern and chaotic environment, which would be a big change for them.
The Akumas in D Gray - Man are created by the Millennium Earl. If Akumas were to enter the Black Butler world, they would be a major threat. Their ability to transform and their inhuman strength would be a challenge for the Black Butler characters. On the other hand, Sebastian's demonic powers and his ability to make contracts could potentially be used to manipulate or destroy the Akumas. The D Gray - Man exorcists are trained to fight Akumas specifically, so their skills would be very useful in this new setting. But the Black Butler characters' knowledge of the local environment and their own unique skills, like Mey - Rin's sharpshooting and Bardroy's combat experience, could also contribute to the fight against the Akumas in ways the D Gray - Man exorcists might not expect.
Kyo could develop by becoming more confident in his human form. He might start to see himself as more than just the cat that is shunned in the Sohma family. With Tohru's influence, he could learn to accept himself fully.
One idea could be to have the characters from 'House' end up in the world of 'Fruits Basket'. Maybe House could try to diagnose the curse that plagues the Sohma family. His rational and often brusque approach would clash with the more emotional and superstitious aspects of the 'Fruits Basket' world.
Well, it could be really interesting. Maybe Naruto characters could end up in the world of Fruits Basket. Naruto might be confused by the Sohma family curse at first. He'd probably try to use his ninja skills to solve the problems there. For example, he could use his shadow clone jutsu to help out in various tasks around the Sohma house.
Well, it could be really interesting. Maybe the characters from Inuyasha end up in the world of Fruits Basket. Inuyasha might be confused by all the Sohma family secrets and the whole curse thing. And the Fruits Basket characters could be scared of Inuyasha at first with his demon side. But then they could learn from each other. For example, Tohru could teach Inuyasha about kindness and acceptance in a different way than Kagome does. And Inuyasha could show the Fruits Basket characters how to be brave in the face of danger.
Well, it could be really interesting. Maybe the characters from Harry Potter could visit the Sohma family in the Fruits Basket world. Harry could be shocked by the curse of the Sohma family and try to find a magical solution to break it. Hermione would be busy researching about the unique situation in Fruits Basket using the library in Hogwarts. Ron might be a bit clueless at first but would gradually get involved in the strange happenings.
When starting to write, don't be afraid to experiment with the characters' voices. House has his very sarcastic and cynical way of speaking, while characters in 'Fruits Basket' like Tohru are very sweet and positive. Let these voices play off each other. For instance, House might make a snarky comment about the Sohma curse, and Tohru could respond with her usual kindness and attempt to make him see the good in the situation. This kind of interaction can create interesting dynamics in your fanfiction.