One popular one might be 'Natsu's Unlikely Bond' where the OC has a unique magic that draws Natsu in. They start off as rivals but gradually develop feelings. Another could be 'A Mate for Natsu' which focuses on the OC being from a different realm and how they adjust to Natsu's world while falling in love with him. There's also 'Natsu and His OC Love' that shows their relationship growing through various adventures together.
First, develop your OC well. Decide on their appearance, personality, and magic abilities if applicable. Then, think about how they would meet Natsu. It could be during a guild mission or by chance in a town. Next, build their relationship gradually. Don't rush into the mate part right away. Show their interactions, like Natsu's reaction to the OC's unique traits.
The OC could be a character with a mysterious past. Maybe they have a hidden power that they are not fully aware of. Natsu, Mirajane, and Erza sense this mystery and are drawn to help the OC uncover their past. As they dig deeper, they find that the OC has a connection to an ancient magic that was thought to be lost. This discovery not only changes the OC's understanding of themselves but also has a significant impact on the relationships within the group.
The OC could have accidentally said or done something that made Natsu feel unwanted or unappreciated in Fairy Tail. For example, if the OC is a new member and got more attention than Natsu in a certain situation, it might have bruised his ego and led to his decision to leave.
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.
For Natsu, you can focus on his loyalty and protectiveness in the relationship. Since it's a secret, he might be more cautious and less impulsive than usual. For the OC, give her some unique traits. Maybe she's shy but has a hidden fiery side like Natsu. You can show her growth as she becomes more confident in the relationship.
In 'natsu x oc dragon slayer fanfiction', a frequently seen theme is the struggle against dark forces. Natsu and the OC team up to fight various villains and protect the world. Another common theme is family. In the Fairy Tail universe, family is important, and the OC may find a new family in the guild, especially with Natsu as a close friend or more. Additionally, the theme of growth, both emotional and in terms of magical power, is a staple in these fanfictions.
Well, in many such fanfictions, it often involves Natsu and Lucy having a special connection related to dragons. Maybe Natsu's dragon powers play a role in bringing them closer in a romantic or fated - mates - like way. For example, they might go on adventures together where Natsu's dragon instincts protect Lucy in a more profound way than in the original story, and their relationship deepens as they face various challenges side by side.
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.
When writing the story, create a plot that showcases their relationship development. It could start with a simple friendship and gradually turn into a deeper romantic connection. Add some conflict, like how the wizarding society might react to their relationship or how Remus' werewolf side could cause problems. This will make the story more engaging.