Well, it could be that Natsu's snap makes him question his own strength and purpose. He might think that if he had been stronger, he could have saved Lucy. So, he embarks on a journey to become even more powerful. Along the way, he meets some characters who either try to stop him from his self - destructive path or join him in his quest for revenge. His relationship with the other guild members would also be severely strained as he's in such a dark place after Lucy's death.
Natsu would likely become much darker. His normally cheerful and carefree attitude would be replaced with a brooding and vengeful one.
It could be about a misunderstanding. Maybe Natsu is under a lot of stress or has been wrongly accused, and Erza's actions or words accidentally trigger his outburst.
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.
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, one possible plot could be that after many adventures together, Natsu finally realizes his deep love for Lucy. He might plan a big, romantic proposal during one of their guild parties. Then the wedding could be a grand affair with all their Fairy Tail friends in attendance. They could exchange heartfelt vows, and the whole guild could celebrate their union with lots of food, music and magic.
Well, perhaps in this fanfiction, Natsu calling Lucy 'baby' is a sign of a new level of closeness in their relationship. It could start with Natsu protecting Lucy in a dangerous situation and instinctively calling her 'baby' as he holds her close. This then leads to Lucy being a bit flustered at first but gradually getting used to it and even liking it, and it becomes a special part of their bond.
One possible plot is that in this fanfic world, female Natsu has a special power that only male Lucy can help her control. So they embark on a journey together. Along the way, they face various challenges like battling powerful demons. Their relationship starts as comrades but gradually develops into a deeper bond as they understand each other more.
Maybe the story could start with Natsu and Lucy going on a special mission. During this mission, they face a great danger that makes them realize how much they mean to each other. Once they return, Natsu decides it's time to get married. The fanfiction could then focus on the wedding preparations, like Lucy choosing her dress and Natsu trying to find the perfect gift for her.
Perhaps the story delves into how they handle disagreements as a married couple. Since Natsu can be impulsive and Lucy is more level - headed at times, they might have to work through their differences. It could also show how their love for each other deepens through these experiences.