Perhaps Nami is under a curse. The curse makes her see Luffy as a threat, even though he's not. So, she ends up hurting him because she's compelled to by the dark magic of the curse until the crew can find a way to break it.
Maybe in that fanfiction, Nami's character is distorted in a way that Luffy, with his straightforward and honest nature, can't stand. For example, if she is portrayed as overly greedy or mean in a way that goes against the essence of her character in the original work.
In some fanfiction scenarios, if Nami were to side with an enemy, even if it was for a seemingly good reason like trying to protect the crew in a way that Luffy doesn't understand. Luffy has a strong sense of loyalty to his crew and seeing Nami on the 'opposing side' might enrage him. He might feel betrayed and his anger would be a natural reaction.
One common theme is friendship. Luffy and Nami have a strong friendship in the original story, and fanfictions often explore how this friendship develops further. For example, they might face a situation that tests the limits of their loyalty to each other.
Nami would be inconsolable at first. Luffy has always been there to protect her, and his sudden death would leave a huge void in her life. She would probably cry for days. As time passed, she would remember all the things Luffy taught her about courage and believing in oneself. Nami would start to take on some of Luffy's leadership qualities in a way. She would be more outspoken about her plans for the crew and more determined to see their dreams through. She would also keep Luffy's memory alive by telling stories of his adventures and his selfless acts to new people they meet on their journey.
Nami might be shocked at first. She'd probably look at Luffy with wide eyes, not believing what she just heard. After all, Luffy is not the most romantic or traditional suitor.
Luffy will most likely use his Gum - Gum abilities. He could stretch his arms to grab Nami and pull her away from the abuser quickly. For example, he might use Gum - Gum Pistol to knock out the bad guys who are abusing Nami.
Another theme is how their relationship affects the crew dynamics. The Straw Hat crew is like a family, and Luffy and Nami's new relationship can bring changes. For instance, some crew members might tease them, while others might be more protective. There are also themes about sacrifice. Luffy might be willing to sacrifice more for Nami when in love, which is a big part of many such fanfictions. It adds a new layer of depth to his character.
In luffy married nami fanfiction, a prevalent theme is growth. Both characters grow as individuals within the marriage. Luffy might become more responsible, and Nami could become more open - hearted. Additionally, the theme of discovery is common. They discover new things about each other and the world around them as a married couple, which adds depth to their relationship and the story as a whole.
The popularity of luffy and nami fanfiction lies in their interesting relationship. They are two very different characters. Luffy is carefree and determined, while Nami is smart and cautious. Their interactions in the original series are full of potential for further exploration in fanfiction.
In one scenario, Luffy might clumsily blurt out the proposal during an adventure. Maybe they're on a beautiful island, and Luffy suddenly realizes his deep feelings for Nami and decides to ask her to marry him right then and there.