It could be a time - traveling version of Blackbeard. Maybe he also discovers time travel and uses it to his advantage to stop Luffy at every turn. He could go back in time and try to prevent Luffy from getting important allies or Devil Fruits.
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.
One Piece's popularity as Luffy was something that happened in One Piece. In One Piece, Luffy was one of the most popular characters as the main character, so he was known as the popular One Piece King. However, Solon was also a very popular character. His performance in One Piece was very outstanding, and he was known as a genius among swordsmen.
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.
Well, in such fanfiction, Luffy's character often becomes more aware of his emotions. Usually, he is so focused on adventure and being the Pirate King, but when he falls in love, he starts to think about someone else's feelings. For example, he might be more hesitant to go on extremely dangerous adventures without considering how his loved one would feel.
Luffy is still alive and kicking in the manga. The story keeps evolving with him at the center of the action, encountering new enemies and growing stronger.