Luffy in the manga is strong, for sure. He's constantly evolving and unlocking new abilities. When compared to others, it depends on the context and the specific situation. Sometimes he might have an edge, while in other cases, his opponents could pose a significant challenge.
One of the main things that make it strong in fanfiction is the creative use of its basic properties. Writers can make Luffy use his stretching in ways that are not shown in the original manga or anime. He could stretch his internal organs to survive otherwise fatal blows. Or he could use his stretched body to create complex structures for defense or to launch multi - directional attacks. This freedom of creativity in fanfiction enhances the perceived strength of his Devil Fruit.
In Luffy harem fanfiction, his relationships often start from friendship. Since Luffy is a friendly and open - hearted character, the female characters are first drawn to him as friends. For example, Nami might start as just a crewmate but gradually develop deeper feelings. His relationships develop as he goes through adventures together with them. They see his courage and selflessness, which makes them admire him more.
Luffy's character would likely become more mature. He'd learn discipline from Whitebeard's strict training regime. His view of the pirate world might expand as he gets insights from Whitebeard's long - standing experience.
Luffy being raised by Doflamingo would be a radical departure from his normal upbringing. Doflamingo's way of life, which involves a lot of underhanded tactics and a disregard for the well - being of others, would shape Luffy in a very different way. He may not have the same innocent and carefree attitude. His goals could be more self - centered, like taking over territories or amassing power for the sake of it. His relationships would also be different. Instead of forming deep bonds of friendship, he might form alliances based on power and convenience. And his approach to challenges would be more in line with Doflamingo's cut - throat style, rather than his own original tenacious but more morally - guided approach.
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.
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.
Female Luffy may have a different body shape. Instead of the muscular build of the original Luffy, she could be more slender but still strong. Her hair might be styled differently too, maybe longer or in a different color. Also, her clothing choices could be more feminine while still maintaining the pirate - like style.