A third theme could be facing greater challenges. In these fanfictions, the challenges are so big that Luffy can't just rely on his normal, laid - back self. He has to be more serious to overcome them.
One great 'luffy gets serious' fanfiction is 'The Serious Luffy Adventure'. In it, Luffy faces a powerful new enemy that forces him to drop his usual carefree attitude and strategize. It shows a different side of Luffy's character.
One great serious Luffy fanfiction could be those that explore his backstory in more depth. For example, a fanfiction might focus on his early days in Foosha Village and how he dealt with the absence of his parents. Another could be about Luffy's training with Rayleigh during the two - year time skip, showing his struggles and growth in a more detailed and serious manner.
You can start by searching on popular fanfiction websites. Use specific keywords like'serious Luffy fanfiction'. Check out the reviews and ratings of the stories to find the ones that are more likely to be what you're looking for.
Rayleigh would be a great candidate. He's an experienced pirate and has already trained Luffy for a while. He has a lot of knowledge about the world of pirates and could give Luffy a talk about the deeper secrets of the Grand Line or how to deal with the powerful enemies that lie ahead.
The change in Naruto's character. Usually, he's the go - lucky and sometimes clumsy ninja. But in these fanfics, when he gets serious, it's like seeing a whole new side of him. It makes the story more exciting as he approaches problems in a different way.
One great 'Harry gets serious' fanfiction is 'The Serious Side of Harry' on FanFiction.net. It shows Harry dealing with the weight of the prophecy in a very mature way.
A third theme could be self - discovery. As Natsu gets serious, he may also discover new aspects of himself. Maybe he realizes he has more power within him than he thought, or he discovers a different way of thinking about his role as a dragon slayer. This can lead to some interesting character arcs in the fanfiction.
It could be about Luffy having an important conversation. Maybe it's about his dreams, his crew, or some kind of revelation he has. Without reading it, it's hard to say exactly.
I'm not sure if there is such a specific fanfiction. There are a vast number of fanfictions out there, but this particular concept might be quite rare or not in line with the general tone of the 'One Piece' series. Fanfiction often explores different relationships and scenarios, but this one seems rather out - of - the - ordinary considering the nature of the characters in the original work.