A possible plot is that the Fairy Tail world is under a curse where all love has been drained. A group of characters decides to go on a quest to find a way to break the curse and in the process, they each get another shot at their own personal love stories. Natsu could find a way to truly express his feelings for Lucy that he has been suppressing all this time.
One plot idea could be a character who has lost their love in a previous battle gets a second chance. Maybe through some magical intervention, they are able to go back in time slightly and change the events that led to their loss. For example, if Gray lost Juvia in a fight, he could be given the opportunity to redo the battle with new knowledge and powers to save her.
Another plot could involve a dimension where the Fairy Tail guild has an evil counterpart. Our heroes have to team up with the good versions of their doppelgangers in that dimension to defeat the common evil. They might face challenges in trusting these new allies who look just like their enemies back home.
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.
One idea could be that Cana tries to prove herself worthy of Gildarts' love by going on a difficult quest alone. Another could be that Gildarts, who has always been a bit of a wanderer, finally decides to settle down for Cana. Or perhaps they have to team up against a powerful dark magic that is threatening the Fairy Tail guild and in the process, their feelings for each other deepen.
One idea could be to explore a different ending for a couple in the show. Maybe they didn't end up together in the original, but in the fanfic, they have a chance encounter years later and rekindle their love.
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.
One idea could be exploring how the next generation of Fairy Tail wizards handle a new dark guild threat. They might have to combine the old and new magic techniques they've learned.
One idea could be that Luffy joins the Fairy Tail guild and his rubber powers amaze everyone. He might participate in a guild - wide competition and use his unique abilities to win in unexpected ways. For example, stretching to reach far - off targets or bouncing around the arena to dodge attacks.