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.
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.
In a fanfic, if a clash of Haoshoku Haki wave knocked someone out, it could lead to a major shift in the power dynamics. For example, the side whose member was knocked out might be thrown into chaos, with their allies panicking or becoming enraged. It could also serve as a plot device to show the overwhelming strength of a particular character who unleashed the Haki wave.
In some fanfictions, Luffy's Haki training often involves extreme challenges. For example, he might face powerful foes that force him to push his Haki to new limits. He could be in situations where his Observation Haki has to be sharpened quickly to avoid deadly attacks. Sometimes, he trains with new mentors in fanfic worlds who have unique ways of teaching Haki, like making him endure intense mental and physical stress to strengthen his Conqueror's Haki.
One interesting aspect is the new types of Haki that fanfic writers come up with. Maybe a combination of different Haki forms that give Luffy an edge. For example, a fusion of Observation and Armament Haki for a super - powerful defense. Another aspect is the training partners. In fanfiction, Luffy could train with characters from other universes or time periods, which makes the training scenarios very exciting.
In a fanfic, the character might recover on their own if they have a latent ability or hidden strength. They could tap into their inner reserves of power, kind of like an adrenaline rush but on a more supernatural level. It could also be that the shock of being knocked out by the Haoshoku Haki wave triggers a transformation or awakening within the character that helps them recover.
Well, Fem Luffy is very straightforward and wears her heart on her sleeve. She'll say what she thinks and do what she wants without much hesitation. Marco is more diplomatic and has a sense of propriety. Their personalities could create some interesting dynamics. For example, when dealing with other pirates or people in general, Fem Luffy might blurt out something that could cause trouble, but Marco would be there to smooth things over. At the same time, Marco might be too reserved for Fem Luffy's liking at first, but over time, she could draw him out of his shell and they could form a great partnership based on their complementary personalities.