Perhaps in a post - apocalyptic Fairy Tail world, Fem Natsu and Laxus are among the few survivors. They have to rely on each other to rebuild the guild and their world. During this time, they discover that their relationship is not just about friendship or guild loyalty, but has deep romantic undertones as they face the hardships of survival and restoration together.
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.
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 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.
Their relationship could develop realistically through shared experiences. For instance, if they both have to protect a young mage from a common enemy. This shared responsibility would force them to communicate more, understand each other's strengths and weaknesses, and gradually form a bond.
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 idea could be that Natsu is exiled due to a false accusation of using dark magic. He then has to journey alone to prove his innocence, encountering new friends and foes along the way. Maybe he discovers a new form of magic during his exile.
One idea could be that Natsu and Irene are forced to team up to defeat a powerful dark magic user. Their opposing personalities at first create conflict, but as they face challenges together, they learn to respect each other's powers.
One interesting plot idea could be Natsu going on a special quest with each member of his harem separately. This would allow for character development of both Natsu and the individual harem members. For example, when he's with Lucy, they could discover a new type of celestial spirit magic that only works in a specific, long - lost realm. Another idea is that an enemy targets Natsu's harem to get to him, so he has to protect them all while also dealing with his growing feelings for each of them.
Perhaps a plot where Future Natsu has lost his memory of the future but still has his enhanced powers. The Fairy Tail guild has to figure out who he is and why he's there while he tries to regain his memories. This could lead to many comical and heartwarming moments as he bonds with the guild members all over again.
In this fanfiction, Natsu could discover that his abandonment was part of a bigger plan within Fairy Tail to protect him from a greater threat. He might initially be angry and resentful, but as he uncovers the truth, he has to decide whether to forgive his old guild or not. He could also meet other characters who were also once abandoned and form a bond with them to face the challenges together.