Maybe in this fanfiction, Natsu leaves because he's afraid of the responsibility of being a father. Lucy, on the other hand, is determined to keep the baby. She spends her pregnancy reflecting on her relationship with Natsu and grows as a person. She starts taking on more jobs to save for the baby's future and also discovers new magical abilities within herself as she faces the upcoming motherhood.
In this fanfiction's plot, it could be that Natsu leaves for some noble but misconstrued reason. He thinks he's protecting Lucy and the unborn child. Lucy is left heartbroken and pregnant. As she progresses through her pregnancy, she tries to find Natsu to make him understand that they can face everything together. Along the way, she has to deal with the judgment of others in the guild, but she stands strong, believing in the love she and Natsu once had.
Well, one possible plot could be that Lucy has to face the challenges of pregnancy alone after Natsu leaves. She might struggle with financial difficulties and the emotional turmoil of raising a child without the father. She could then find support in her friends in the guild, who help her through the tough times and she eventually becomes a strong, independent mother.
Well, the two main characters are Natsu and Lucy. Natsu's departure is the inciting incident. Lucy, now pregnant, has to face the world on her own. Her character will probably show a great deal of growth as she deals with single motherhood. While the story is mainly about them, other characters from their guild might also play important roles, such as providing support or causing additional conflict in relation to Lucy's situation.
Well, one possible plot could be that Natsu, as the king, has to deal with the political implications of Lucy being pregnant. He might face challenges from other kingdoms who see a potential heir as a threat. And Lucy, as the queen, could be struggling with her new role and the physical and emotional changes of pregnancy.
One possible plot twist could be that Natsu initially doesn't believe it's his child. Maybe he has some self - doubts due to his past or his own insecurities. Another twist could be that there are external forces trying to harm Lucy because of her pregnancy, like dark guilds seeing it as a way to get to Natsu. And perhaps the pregnancy could also bring out a new side of Natsu, a more protective and responsible side that no one has seen before.
Well, one possible plot could be that Natsu and Lucy's relationship evolves from friendship to something more romantic. Then, an unexpected pregnancy occurs which throws their lives into chaos. They might have to face the reactions of their friends and deal with their own fears and insecurities about becoming parents.
It could be that there are some internal issues within Fairy Tail that make her leave while being pregnant. For example, there might be a prophecy or a curse that she believes could harm her baby if she stays. So, in order to break free from that potential threat, she decides to leave. Also, she may be facing some personal conflicts with other members of Fairy Tail regarding her pregnancy, like some not being supportive or having different views on how she should handle it, which ultimately drives her to leave.
Well, one possibility could be that Natsu leaves the guild because of a personal mission. Maybe he discovers a dark secret about his past that he believes can only be solved alone, so he leaves Fairy Tail to find out the truth without putting his friends in danger.
Perhaps Natsu kidnaps Lucy as a prank that goes wrong. He initially thinks it'll be a funny joke, like taking her away during a guild party just for a bit of chaos. But then things get out of hand. Lucy might be really angry at first, but as they are alone together, they start to have some deep conversations and understand each other better.
The plot could develop with them preparing for the baby. They might start looking for a bigger place to live. Natsu could go on quests to earn more money for the baby's needs.
One plot idea could be that a magic spell goes wrong and Lucy ends up pregnant. Natsu is initially shocked but then quickly embraces the idea of being a father. They then have to deal with the guild's reactions, some of which are positive and some negative.
The father of the baby could potentially be an antagonist if he has a different view on the pregnancy than Lucy. For example, if he wants her to have an abortion and she wants to keep the baby, he could create obstacles for her.