What could be an interesting plot for a Fairy Tail Rosario Vampire crossover fanfiction?

Gray and Kurumu would be an interesting combination. Gray is the cool, ice - using mage, and Kurumu is the succubus with her charm powers. Kurumu might be initially attracted to Gray because of his looks, but Gray would be all business. Their relationship could develop from Kurumu's attempts at flirting to a real friendship as they face common enemies together in a crossover story.

One interesting plot could be that a vampire from the Rosario Vampire world somehow ends up at Hogwarts. Maybe they're initially mistaken for a dark wizard because of their vampiric abilities. They could then form an unlikely friendship with Harry Potter and his friends, and together they have to face a new threat that combines the magic of the Harry Potter universe with the unique powers and challenges of the vampire world.

A great plot could involve a powerful enemy that has the ability to drain the 'viewtiful' energy from Joe. Tsukune and his friends notice the weakened Joe and decide to help. They all train together, combining their different powers and skills. The story could then build up to an epic showdown where they all have to use their combined strength to defeat the enemy and Joe regains his full 'viewtiful' power.

Well, perhaps in the fanfiction, Godzilla is a result of some dark magic experiment gone wrong in the Fairy Tail universe. The guilds have to deal with this giant creature that is causing destruction everywhere. Lucy might use her Celestial Spirits to try and hold Godzilla off while the others come up with a plan. Gray could use his ice - make magic to try and freeze parts of Godzilla to slow it down. And in the end, they find a way to reverse the dark magic and turn Godzilla back to normal or send it away.

A cool plot might be that a dark wizard from Fairy Tail discovers a spell that can open portals to other dimensions and accidentally pulls Inuyasha, Kagome, Shippo, etc. into their world. The Fairy Tail guild decides to help them get back home. But during this time, they realize that there are some similarities between the demons in Inuyasha's world and the dark creatures they fight in their own world. So, they team up. Inuyasha and Natsu could have a friendly rivalry over who is stronger and in the end, they combine their powers to defeat an ancient evil that was awakened by the portal - opening spell.

One possible plot could be that Ben Tennyson, while on a trip with his family, somehow gets transported to the world of Fairy Tail. His Omnitrix malfunctions due to the different magical energies in that world. The Fairy Tail guild members are initially suspicious of him but when they see his alien forms in action against some common enemies like the Dark Guilds, they start to work together. Ben could learn about magic from the guild members and they could learn about his advanced technology.

One possible plot could be that Lucario, with its aura - sensing abilities, detects a strange magical disturbance in the Fairy Tail world. It travels there and teams up with Natsu. Lucario's combat skills and ability to sense opponents' moves before they happen would be a great asset in battles against powerful dark mages. Together, they embark on a journey to find the source of the disturbance and end up uncovering a conspiracy that threatens both the Pokémon world and the Fairy Tail world.

One possible plot could be that Goku somehow gets transported to the Fairy Tail world. He could join forces with Natsu and the gang to fight against a common enemy like Acnologia. Goku's power levels would be off the charts compared to most in Fairy Tail, but he'd be intrigued by their magic. Maybe he'd learn some magic himself or teach them some of his ki techniques.

A cool plot might be that a powerful dark wizard in the Fairy Tail world discovers a way to control some of Ben's aliens. Ben has to seek help from Fairy Tail mages to break the control and then they join forces. The Fairy Tail members are amazed by Ben's ability to transform and his alien powers, and they work together to stop the dark wizard's plan to take over both worlds.

One possible plot could be that the Fairy Tail guild discovers a strange energy similar to the ki in the DBZ universe. Natsu, being the curious and powerful wizard he is, decides to investigate. He then somehow gets transported to the DBZ world. There, he meets Goku, who is intrigued by Natsu's magic. Together, they have to face a new enemy that is a threat to both their worlds. This enemy could be a powerful wizard who has found a way to combine dark magic with the power of the dragon balls.