Well, it could be that Lucy has a misunderstanding. Maybe she overhears something that makes her think Natsu is planning to leave the guild without saying goodbye. So, in a fit of panic and anger, she kidnaps him to get an explanation. Then, as the story progresses, they have a heart - to - heart conversation where the misunderstanding is cleared up. It could also be a situation where Lucy is competing with someone else for Natsu's attention, and she thinks that by kidnapping him, she can have him all to herself for a while and figure out how to make him like her more.
It could be another guild that sees Natsu as a threat. They might find out about Lucy kidnapping Natsu and try to use the situation to their advantage. For example, they could try to steal Natsu's magic or get information out of him while he's in a vulnerable state. Another possible antagonist could be a character who has a grudge against Lucy. They might try to stop her from getting away with the kidnapping or use it as a way to get revenge on her.
One character that would be interesting to include is Mirajane. She has a motherly and observant nature. She could be the one to nudge Natsu and Lucy in the right direction when it comes to their relationship. For instance, she might arrange for them to go on a mission together that she knows will bring them closer. Laxus could also be in the fanfiction. His powerful presence can create a sense of danger or protection. If there's an outside threat to the guild while Natsu and Lucy are exploring their relationship, Laxus could be at the forefront of defending the guild, which would impact Natsu and Lucy's situation. And don't forget about Cana. She could be the one to create some light - hearted chaos, like daring Natsu and Lucy to do something that ends up bringing them closer, such as a bet that leads to a shared adventure.
As they travel, their bond deepens. They start to rely on each other more. Natsu becomes more protective of Lucy, and Lucy begins to understand Natsu's impulsive nature better.
Well, perhaps Laxus has some misguided notion that Lucy has information vital to the guild's safety. So he kidnaps her thinking he can extract it from her quickly. But in reality, Lucy has no such information and she has to convince Laxus of that.
She might start to blush furiously. Given her character, she is a bit shy when it comes to romantic matters. And then she might start to stammer out a response, not really sure what to say at first. As she composes herself, she could tell Natsu that she has feelings for him too but in a very gentle and sincere way.
In 'natsu falls in love with lucy fanfiction', the author might focus on building the relationship gradually. They could start from small interactions that gradually grow into deeper feelings. For example, they might describe how Natsu starts to notice Lucy's little quirks and how those things become endearing to him, leading to his love for her.
In fanfiction, Natsu and Lucy's love story is often filled with tender moments. They have a natural chemistry in the original series that fanfic writers expand on. For example, some stories might focus on how Natsu realizes his deeper feelings for Lucy during a dangerous mission. He protects her more fiercely than ever, and in those intense moments, their bond deepens into something more romantic.
One aspect of their married life in fanfiction could be the domestic side. Lucy might try to get Natsu to be more organized at home, while Natsu would bring his energetic and fun - loving nature into their household. They would probably have a lot of cute and comical moments, like when Natsu accidentally burns the dinner and Lucy just shakes her head and laughs it off. Their love would continue to grow as they share these everyday experiences.
Well, Natsu might protect Lucy by using his dragon - like senses. In the Fairy Tail world, his enhanced senses can detect danger before it reaches Lucy. So, he could quickly react and pull her out of harm's way. Also, his loyalty to Lucy and the Fairy Tail guild drives him to protect her. He would not let any harm come to her, whether it's from other guilds who might have a grudge against Fairy Tail or from individual villains in the fanfiction. He'll be there to fight for her safety.