Well, in this fanfiction, perhaps the relationship between Luffy and Rayleigh is explored in more depth. We might see Rayleigh sharing his old tales of the Pirate King Gol D. Roger with Luffy. This could inspire Luffy even more in his journey to become the Pirate King. Also, Luffy's character growth in terms of leadership could be a great part. Under Rayleigh's guidance, he might learn how to better lead his crew and make more strategic decisions during battles.
Maybe an ancient sage in Naruto's own world who has long - been in seclusion. This sage has knowledge of different power systems beyond just chakra. He notices Naruto's pure heart and strong will and decides to pass on his knowledge of haki to Naruto, believing that Naruto can use it for the greater good of the ninja world.
Probably, the main plot is about Luffy's transformation under Rayleigh's training. Rayleigh could be teaching Luffy about the secrets of the Grand Line, the lost history, and advanced combat skills. Luffy then uses what he has learned to face new and more powerful enemies. For instance, he might encounter some strong pirates who are also after the One Piece, and he has to use his newly acquired skills to defeat them and protect his crew. The plot could also involve Luffy's crewmates waiting for him during his training and their own mini - adventures in the meantime.
There's not enough information to know exactly who Rayleigh is. It could be a common name for a person in this context, maybe a local storyteller or someone known within a particular community.
Well, there are 'luffy haki fanfic' stories that focus on the development of his Observation Haki. In some of them, Luffy is able to predict the moves of his opponents far in advance, like being able to dodge attacks that are seemingly impossible to avoid. These fanfics often add new elements to the use of his Haki, like being able to sense the emotions behind an opponent's attack as well.
Dumbledore could be the one to teach Harry about Haki. Dumbledore, with his vast knowledge of magic and the unknown, might have come across Haki in his travels. He could recognize the signs of Haki in Harry and take it upon himself to guide Harry in understanding and controlling this new power. He would use his calm and wise approach, just like when he teaches Harry about other aspects of magic.
In this kind of fanfiction, usually the plot might involve Luffy starting to discover his latent conqueror's haki power. Maybe he first experiences some intense battles where he unknowingly shows signs of it. Then, he might meet an old and wise character who recognizes this power in him and starts to guide him on how to control and use it effectively.
You can start by looking on fanfic websites like Archive of Our Own (AO3) or FanFiction.net. Just type 'luffy haki fanfic' into their search bars, and a whole bunch of stories should come up. These platforms have a large collection of One Piece - related fanfics, including those focused on Luffy's Haki.
If Luffy knew Haki early, it would likely give him a significant advantage. He could take on stronger opponents sooner and perhaps even prevent some of the setbacks he faced originally. This could lead to a quicker rise to power and a different dynamic with his crew.
Aside from Luffy, characters like Ace might show up in this type of fanfiction. Ace, being Luffy's brother, could have some connection to Luffy's discovery of conquerer's haki, perhaps through memories or some form of spiritual guidance. Additionally, some powerful enemies might be present. These enemies would serve as the motivation for Luffy to quickly master the conqueror's haki in order to defeat them and protect his crew. There may also be some minor characters from the One Piece world who assist Luffy in his learning process, like the inhabitants of a special village that has knowledge about haki.