The theme of acceptance is quite common. Fem Luffy often has to be accepted by the other characters in the story. This could be because she's different due to her gender or her slightly different personality traits. Also, the theme of self - discovery is prevalent. As fem Luffy navigates the pirate world, she discovers more about herself, her abilities, and her place in the grand scheme of things.
Nami could also be a common character. She might help Luffy manage the financial aspects of his admiral duties, as well as use her navigation skills to assist in any navy - related voyages. And of course, she'd be there to keep Luffy in check when he gets too carried away.
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.
One popular luffy and fem luffy fanfiction is 'Fem Luffy's Adventure'. It shows a different side of Luffy if she was a female, with unique storylines and character developments. Another one could be 'Fem Luffy in a New World' which explores how fem Luffy might interact with the other characters in the One Piece world in new and interesting ways.
Luffy would probably still value his friends above all else. However, as a Celestial Dragon, he might have more power at his disposal. This could make him a bit more confident in his actions, but also more responsible. He might feel the need to use his influence to protect not just his crew, but also the oppressed people he meets, in a more official way.
His leadership style could change significantly. In the original, he leads with his heart and by example, but in a dark fanfiction, he could be more of a dictator - like leader within his crew, making decisions without much input from others and demanding strict obedience. His goals might also shift from just finding the One Piece and having a grand adventure to seeking power for more self - centered reasons, like revenge or dominance.
A possible fanfiction could be about blind Luffy being mistaken for a powerful shinobi because of his strange abilities. His rubbery body and unique way of fighting, combined with his enhanced non - visual senses, could make the Naruto characters view him as a mysterious and dangerous opponent or ally. This could lead to all sorts of adventures and misunderstandings as he tries to navigate the complex world of ninjas.
He could face powerful sword - using pirates. Since Luffy now has a sword, he would attract the attention of other sword - masters in the pirate world. These opponents would test his new - found sword skills and force him to improve quickly.