Well, a great plot might be that a new character enters the Fairy Tail world who is already under a Beauty and the Beast - like curse. The Fairy Tail members don't initially trust this beast - like person but as time goes on, they discover his good heart. Maybe he has some special power that could help the guild in a future battle, and in the process of working together, the curse is broken.
A plot could involve a magical artifact from the Fairy Tail universe that, when misused, casts a Beauty and the Beast - type curse on a town. The Fairy Tail wizards have to figure out how to break the curse. They might find that the key lies in an old legend about a love that transcended appearances. So they have to recreate that kind of love between two people in the town, one who has been turned into a beast and the other a beauty.
One idea could be that the Beast has a secret power that he's been hiding from Belle. Maybe he can communicate with the forest animals in a unique way and they help him in his quest to win Belle's true love. Another could be a backstory for the Enchantress who cursed the Beast, showing her reasons and her own journey. Or perhaps Belle discovers a hidden library in the castle that contains the secrets of breaking the curse not just for the Beast but for the entire enchanted castle and its inhabitants.
You could also make an OC beast that has a special connection with the Celestial Spirits. Maybe it was once a spirit itself but got transformed into a beast. This connection could lead to interesting storylines involving the Celestial Spirit World and the regular Fairy Tail world.
One idea could be exploring the Beast's past more deeply. Maybe a story about his life before the curse, his relationship with his family and how it all led to his current situation.
One idea could be that Belle discovers a hidden garden in the Beast's castle that has magical plants which can talk and offer her advice. Another could be a backstory for the Beast, like how he got cursed in a more detailed and different way than in the original story. For example, he was tricked by a jealous wizard who wanted the castle for himself.
One idea could be a new character arriving at Fairy Hills and having to adapt to the unique living situation. They could face challenges like getting along with the different personalities of the Fairy Tail mages living there.
Maybe the Dark Beauty is not truly human but a being from another dimension. She and the Beast have a connection that transcends their different forms. They must figure out how to break the curse on the Beast's castle while also dealing with her other - dimensional nature.
Another plot could involve Bardock having to adapt to the magic - based society of Fairy Tail. He might initially struggle with understanding how magic works, but then discovers a way to combine his Saiyan power with the magic there. For example, he could learn to use ki - based attacks in harmony with Fairy Tail's elemental magics. This would create a unique fighting style that surprises both his allies and enemies.
One idea could be a crossover adventure where characters from Fairy Tail and Negima team up to fight a common, powerful enemy. For example, they might face a dark wizard who has the ability to steal magic from both worlds.
One idea could be that the main couple from Fairy Tail goes on a honeymoon to a magical island. There, they discover a hidden ancient magic that they have to protect from villains who also find out about it. Another plot could involve them facing relationship challenges during the honeymoon, like misunderstandings due to magic gone wrong. For example, a spell makes one of them forget parts of their relationship, and they have to work through it to rekindle their love.
In a 'Fairy Tail WW2 Fanfiction', a possible plot could be that the guild discovers a hidden magical dimension that is somehow connected to the events of WW2. They enter this dimension to try and stop a dark force that is influencing the war from the shadows. Some of the characters could form alliances with real - life military personnel who are open - minded enough to accept their help. This would lead to interesting interactions between the magical and non - magical worlds during the war.