Well, a plot could involve Natsu being completely oblivious to Mirajane's jealousy. He might be so focused on his own goals, like defeating a powerful enemy or achieving a certain magical feat, that he doesn't notice how his actions are making Mirajane feel. Meanwhile, Mirajane is seething with jealousy and the other guild members start to notice the tension between them, which could lead to some interesting interactions and attempts at mediation by their friends.
The main characters are clearly Natsu and Mirajane. Natsu is often portrayed as a hot - headed and powerful wizard. Mirajane, on the other hand, is a strong and beautiful character with her own set of skills and a complex personality.
One idea could be that Natsu and Mirajane start a family in a peaceful post - guild - war era. Their kids inherit unique magical abilities from both of them and they have to train and guide their children through the magical world's challenges.
One possible plot could be that the kidnappers are from a rival guild who want to use Natsu as leverage against Fairy Tail. Gray could then embark on a solo mission to rescue Natsu, facing various traps and enemies along the way. He might have to use his ice - make magic in creative ways to overcome obstacles.
One possible storyline could be a quest where the three of them have to work together to defeat a powerful dark wizard. Natsu's brute strength, Erza's strategic combat skills, and Mirajane's shape - shifting abilities would make for an amazing team. They could start off with some initial bickering due to their different personalities but gradually grow to respect and rely on each other more as the adventure progresses.
One idea could be a story where they go on a quest together. Maybe they have to find a rare magical item. Natsu's impulsiveness, Mirajane's charm, and Erza's strict leadership combine in interesting ways during the adventure.
Perhaps the OC is from a different dimension where magic works in a strange way. Natsu, Mirajane, and Erza are intrigued by this. They team up to help the OC understand and control their magic in the world they are in now. Along the way, they encounter a powerful dark wizard who wants to use the OC's unique magic for evil. So, they have to fight together to protect the OC and the world from this threat.
One interesting plotline could be a time - travel story. For example, natsu, lisanna, and mirajane could be sent back in time to when they were younger and have to deal with past events while also trying not to change the future too much. It would be full of nostalgic moments and also opportunities for character growth.
One good Mirajane x Natsu fanfic could be 'The Unlikely Bond'. It explores their relationship in a world where they have to team up for a special mission. The author does a great job of showing how their different personalities interact.
A plot could be that during a difficult mission, Mirajane discovers she's pregnant. Natsu then has to balance protecting her and completing the mission. This would add a layer of tension and emotion to the story.
One plot idea could be that Natsu accidentally discovers Mirajane's secret hobby, like painting. As he tries to help her show her work, they grow closer. Another could be a mission where they get separated from the rest of the guild and have to rely on each other for survival, leading to a realization of their feelings. Or perhaps a magic - induced amnesia situation where Natsu forgets everyone but Mirajane is determined to make him remember their relationship.