Perhaps in the fanfiction, there's a curse that affects the magic in the Fairy Tail world. Female Natsu and Laxus are two of the few mages who seem to be somewhat immune. They are tasked with finding the source of the curse. During their journey, they discover secrets about each other's pasts. Laxus might learn about Female Natsu's insecurities related to her gender - flipped version of Natsu, and she could learn about his own family issues. This mutual understanding deepens their bond.
A possible plot could involve a magical tournament. Female Natsu enters to prove herself, and Laxus also participates. They end up as reluctant allies at first. As the tournament progresses, they start to see each other in a new light. Their interactions during the battles, the post - fight banter, and the times they have to train together can all be opportunities for their relationship to grow. Maybe there's a sub - plot where an old enemy of Laxus tries to use Female Natsu against him, which further complicates their relationship.
A plot could involve Fem Natsu accidentally using her magic in a way that affects Laxus in an unexpected manner. For example, her fire magic could trigger some latent power in Laxus, and as they figure out what's going on, they become closer. This could also lead to some interesting training sessions between them as they try to control this newfound power connection.
One idea could be a story where Mira and Laxus are paired on a difficult mission. They start off bickering as they have different approaches, but as the mission progresses, they begin to understand and respect each other more. This could lead to a budding romance as they see the good in one another.
I've read one where Natsu and Female Laxus compete in a guild - wide tournament. At first, it's all about winning for themselves. But as the tournament goes on, they start to understand that they are both representing Fairy Tail. They begin to work together in a way, like when they face an opponent who is using dirty tricks. They combine their powers to defeat the cheater and in the end, they both gain a new respect for each other and for the guild.
One frequent theme is rivalry. They are both strong characters in Fairy Tail. So, in many fanfictions, there is a friendly rivalry between them. They might compete to see who can complete a mission faster or who is stronger in a sparring match. Also, the theme of self - discovery can be seen. As they interact, they learn more about themselves, like Natsu learning to be more strategic from Female Laxus and Female Laxus learning to be more spontaneous from Natsu.
One plot idea could be that Natsu and Juvia are on a mission together in a mysterious, ice - covered land. Juvia's water magic is affected by the extreme cold, and Natsu has to use his fire magic to keep her safe while they search for a powerful, lost artifact. Along the way, they start to understand each other better and develop a deeper bond.
One plot idea could be that Juvia and Natsu are forced to team up on a mission in a dangerous, enchanted forest. Along the way, Juvia's feelings for Gray start to shift towards Natsu as she sees his determination and kindness in a new light. Another could be a body - swap situation where Juvia and Natsu swap bodies and have to learn to deal with each other's powers and personalities, leading to some comical and heartwarming moments. A third idea is that in an alternate universe, Juvia and Natsu are childhood friends, and they have to face the challenges of growing up and protecting their world together, with their relationship evolving from friendship to something more romantic.
Well, a plot could revolve around a competition in the Fairy Tail guild where Millianna and Natsu are teamed up. At first, they don't get along well because of their different personalities. Millianna is more sly and Natsu is brash. But as they face challenges in the competition, they start to understand each other better. Maybe there's a task where they have to rescue a group of kittens, which plays to Millianna's love for cats. Natsu, on the other hand, has to use his strength to fight off the bad guys who are trying to stop them. In the end, they become closer friends and realize they make a great team.
The OC could be a time - traveler who ends up in the Fairy Tail world. She meets Natsu and tries to hide her true identity. But Natsu, being perceptive, notices something odd. They start to team up for various missions, and the OC has to use her knowledge of future events to help Natsu and Fairy Tail, all the while falling for Natsu's brash but kind personality.
One popular storyline could be Natsu and Laxus teaming up against a powerful dark guild. They have different fighting styles but learn to combine their strengths. Natsu's brute force and Laxus' lightning - based attacks could make for some epic battle scenes.
A really interesting plot would be if there was a prophecy about Freed and Laxus having to team up to save the Fairy Tail guild from an internal threat. They would have to face their own insecurities and past mistakes while trying to figure out who the traitor in the guild is. Along the way, they would strengthen their bond and prove their loyalty to Fairy Tail.