A frequently seen theme is the interaction between different character personalities. In a crossover with 'Naruto', for instance, the determined and often hot - headed characters from 'Naruto' meet the more reserved or complex characters from 'Blue Exorcist'. This leads to some interesting character development and relationships. Also, the theme of good vs evil in a new context is common. Since both the original 'Blue Exorcist' and the crossed - over series usually have their own ideas about what is good and what is evil, it creates new scenarios to explore this concept.
Another idea for a Blue Exorcist Demon Tail fanfiction is a story centered around a character who has the powers of both an exorcist and a Fairy Tail mage. This character could be an outcast in both worlds, not fully accepted by the exorcist community because of their magic and not fully trusted by the Fairy Tail guild because of their connection to demons. They would have to find their own path and prove their worth in a world full of prejudice.
One common theme is the clash of different magical systems. Harry Potter has its own kind of magic with wands and spells, while Blue Exorcist has exorcism techniques. Another theme is friendship. Characters from both series often form new friendships or have to deal with differences in how they view friendship. For example, a Hogwarts student might be more used to having friends within their own house, while in Blue Exorcist, friendships are formed based on different criteria at the True Cross Academy.
There's also 'Cross - Realm Defenders'. In this fanfiction, the demon - slaying aspects of both series are the focus. Characters from both shows form a sort of alliance. It shows how Kuwabara from Yuy Yu Hakusho might react to the more formal exorcist system in Blue Exorcist, and how the Blue Exorcist characters would view Kuwabara's unorthodox fighting style. It's full of action and some really cool battle scenes.
Sure. One popular 'blue exorcist crossover fanfiction' is the one that crosses over with 'Soul Eater'. It combines the unique exorcism world of 'Blue Exorcist' with the weapon - meister system of 'Soul Eater'. Another great one is the crossover with 'Fullmetal Alchemist'. It's interesting to see how the characters from 'Blue Exorcist' interact with the alchemists in that world.
Well, Naruto's Rasengan could potentially be combined with Rin's blue flames. Imagine Naruto creating a Rasengan infused with the power of Rin's blue flames. It would be an extremely powerful and destructive attack. The Rasengan's spinning chakra could be enhanced by the purifying and burning properties of the blue flames, making it effective against both physical and spiritual enemies.
Maybe a character from Blue Exorcist gets summoned into the Fate universe by mistake. They then have to adapt to the new rules and magic there, and form alliances with the Fate characters to find a way back home. Along the way, they discover new aspects of their own powers.
A third plot idea is that some of the characters from Blue Exorcist end up in the Naruto universe. Rin and his friends could be intrigued by the concept of ninjas and chakra. They might learn some ninja techniques and in turn, teach the ninja about exorcism. This could lead to a new generation of ninja - exorcists in the Naruto world. They could also help the ninja deal with a dark force that has some similarities to demons from their own world.
One idea could be an OC tamer who has the ability to communicate with rare and powerful demons. For example, they might be able to understand the language of ancient demons that others can't. This would give them an edge in battles and in understanding the demon world better.
A great one is 'Potter and the Exorcist's Adventure'. It has a really cool plot where Harry Potter somehow ends up in the world of Blue Exorcist. The author does a great job of making the two worlds blend. Harry's magic is pitted against the demons in the Blue Exorcist world, and there are some really intense battle scenes. It also explores how the different relationships in both series would work when the characters interact.