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.
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.
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.
In some fanfictions, Naruto might discover haki during a particularly intense battle. Maybe when facing an enemy with an unusual power that his regular jutsu can't handle, he unknowingly taps into his latent haki ability.
Well, in such a fanfic, Naruto could start learning haki perhaps from a mysterious traveler who has knowledge of different worlds. He might first struggle with understanding the concept of haki, like differentiating between Observation Haki and Armament Haki. Then, as he trains, he could gradually incorporate haki into his existing jutsu. For example, using Armament Haki to strengthen his Rasengan, making it even more powerful and capable of breaking through tough defenses that normal Rasengan couldn't. This would make him an even more formidable opponent in battles against tough enemies like Madara or Kaguya.
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.
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.
One Piece was a very large comic and animation work, which described Luffy's family story in a very wide range of plots. Luffy's father was Admiral Zoro, his mother was the pirate Nami, and he had two older brothers, Choba and Franky, as well as an older sister, Nicole Robin. In One Piece's storyline, Luffy and his family experienced many adventures and challenges in pursuit of the dream of becoming One Piece.
One Piece's middle lane character Fei Xueba was furious. In the sixth episode," Luffy VS One of the Four Emperors, King of Beasts," Luffy learned to be domineering in his battle with White Beard, one of the Four Emperors.