A really interesting storyline could be that Hisui is actually a long - lost relative of someone important in Natsu's past. As they interact, they start to notice strange similarities in their magic or in their family heirlooms. They then embark on a journey to discover the truth about their connection. Along the way, they encounter many obstacles and have to fight side by side. This journey of discovery not only deepens their bond but also reveals secrets about the Fairy Tail world that were long forgotten.
Well, a great storyline might involve Hisui getting lost in a dangerous magical realm and Natsu being the one to go and rescue her. During their time in the realm, they rely on each other's strengths. Hisui uses her knowledge and diplomatic skills, while Natsu uses his brute strength and dragon slayer magic. This shared experience brings them closer. Or perhaps there's a prophecy about Hisui and Natsu that they initially don't believe in, but as events unfold, they start to see the truth in it.
One great example could be those that explore their relationship in an alternate universe. Maybe a world where magic is used in different ways. Another is the ones that focus on how they first meet in the fanfiction world. It could be a chance encounter during a magical event. And there are also fanfictions that deal with them facing a common enemy together and how that experience brings them closer.
They often interact with Natsu being his boisterous self and Hisui being intrigued by his energy. For example, in some fanfictions, Natsu might show Hisui a new type of magic, and Hisui would be both amazed and a bit cautious.
Another storyline could involve the reactions of their friends in Fairy Tail. Some might be overjoyed and helpful, like Levy who could give Lucy advice on pregnancy. Others, like Gray, might tease Natsu about becoming a father. Their friends could also organize a big celebration for the upcoming baby, which would show the strong sense of community in Fairy Tail.
For Hisui and Natsu's character development, it's important to give them growth arcs that are in line with their existing traits. Hisui could start off as a bit reserved and formal, but as she spends time with Natsu, she becomes more open - minded and adventurous. Natsu, on the other hand, could learn more about responsibility and respect for authority through his relationship with Hisui. You can use different plot events like battles or diplomatic meetings to showcase these changes in their characters. Also, let their relationship progress gradually, from initial distrust or indifference to mutual respect and affection.
One possible storyline could be that the OC tries to find Natsu after he leaves Fairy Tail. The OC might have a special bond with Natsu and be determined to bring him back. They could go on a journey where they face various challenges and meet new characters along the way. Another idea is that the OC is actually the reason Natsu leaves Fairy Tail in the first place. Maybe there was a misunderstanding or a conflict between them that led to his departure, and the story could be about how they resolve it.
Another idea is that the OC is from a different land and has a completely different view of magic compared to the people in the Fairy Tail world. Hisui, as someone interested in different cultures and magics, is intrigued by the OC. They start a journey to understand each other's worlds better. During this journey, they encounter various magical creatures and have to overcome cultural misunderstandings and the opposition of some who don't like the idea of mixing different magics.
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.
A possible storyline is a friendly competition between them. They bet on who can complete a series of challenges first. These challenges could involve things like rescuing a certain number of people in a village within a time limit, or collecting rare magical items. Along the way, they learn more about each other's strengths and weaknesses, and also grow closer as friends. This kind of storyline can also have some humorous moments, like when Natsu accidentally sets something on fire during a task that Gray then has to quickly freeze to prevent a disaster.
One great storyline could be Natsu and Erza having to protect their family from a powerful dark guild. They'd use their combined magic and teamwork to fend off the threats. Another could be them raising a young child with special powers within their family, teaching the child about love and friendship just like they've learned in Fairy Tail.
One popular storyline could be them going on a dangerous mission together. Mirajane's powerful magic and Natsu's dragon - slayer abilities would make for an exciting adventure. They might face a powerful dark guild and have to rely on each other to survive.