They could go on an adventure to find a powerful treasure that combines the power of the One Piece and some kind of ninja - related artifact. Maybe they'd have to fight against a new enemy that is a combination of pirates and rogue ninjas. They might travel to new islands where Naruto's ninjutsu would be useful for exploring hidden caves, and Luffy's stretching ability would help them reach high places or cross large gaps.
The crewmates would have a range of reactions. For one, they trust Luffy's ability to handle himself, but they'd also be eager to reunite with him. Luffy's impulsive nature often leads him into adventures, and this time it's in a whole new world. The more level - headed ones like Nami and Robin would be thinking of strategies to either bring him back or join him. The fighters like Zoro and Sanji would be prepared to defend Luffy against any threats in this new and unknown Naruto world. And the rest of the crew would contribute in their own unique ways, whether it's through humor like Brook or scientific exploration like Franky.
Common themes in 'naruto luffy brother fanfiction' include power - sharing. Given their unique abilities, fans like to write about how they would teach each other or combine their powers. Also, friendship is a big theme. Even though they are brothers in these stories, their relationships with other characters from their respective worlds are still important, and the fanfictions often explore how they maintain those friendships while being brothers. And of course, there's the theme of family. The idea of them being brothers brings in a whole new family dynamic that wasn't present in the original stories.
Well, there is some 'naruto luffy brother fanfiction'. Some of them explore how their different powers would interact if they were brothers. For example, Naruto's ninjutsu and Luffy's Devil Fruit abilities could make for some really exciting adventures together. Also, the different worlds they come from, the Hidden Leaf Village and the Grand Line, could be combined in creative ways in these fanfictions.
Naruto might give Luffy training in stealth. Since Naruto is a ninja, he is well - versed in moving around unnoticed. Luffy, on the other hand, is more of a straightforward fighter. So Naruto could show him how to approach enemies without being detected first, which would be a new and useful skill for Luffy in his pirate adventures.
Naruto might also be determined to change his brother's mind. He would keep showing his good side, like his kindness and his strong will to protect the village. He could think that by being a better person, his brother will eventually stop hating him. He may even go through some tough training to prove himself not only to his brother but also to the whole village. And in the process, he may face a lot of difficulties and rejections from his brother, but he won't give up easily.
Sasuke would be furious. He already has a strong sense of justice and loyalty to Naruto. He'd likely immediately start looking for Naruto, using his Sharingan to track any possible leads. He might even go against the village rules if he thought the village was involved in Naruto's kidnapping.
Sakura might be really surprised at first. She could offer to help Naruto with his girl disguise, teaching him things like how to do his hair or choose the right clothes. She might also find it a bit funny but would be supportive in the end, seeing it as part of a mission. Sasuke, on the other hand, might be a bit more aloof. He would probably just raise an eyebrow at Naruto's new look but wouldn't make a big fuss about it as long as it was for a good reason.
His friends would be shocked at first. Sasuke might feel a sense of responsibility to find Naruto and bring him back. Sakura would probably feel guilty, especially if she was somehow involved in the situation that led to Naruto being cheated on.
There might also be a sense of self - doubt. Naruto may start to question his own judgment. He thought his friends were true to him, so the betrayal could make him wonder if he was wrong about them all along. He might also doubt his own worthiness as a friend and leader, which could have a long - term impact on his self - esteem.