Shanks might interact with Luffy's crew in a very friendly and father - like way. He could pat the crew members on the back, give them words of encouragement, and share his experiences with them.
I think it has the potential to be very engaging. A marine joining Luffy's crew would bring in a clash of ideologies and force both the marine and the crew to adapt and grow. It could lead to some unexpected plot twists and character developments.
Zoro would be deeply affected. He has sworn to follow Luffy and his death would be a huge blow. He might feel like he failed in his duty to protect the captain. He would likely become more withdrawn at first, but then focus on getting stronger to avenge Luffy if there was someone to blame for his death.
Obviously, they will support Luffy all the way. He is their captain, and they have complete faith in him. They have been through so much together, and they know Luffy's strength and determination.
If a marine joins Luffy's crew in a fanfic, it could be quite interesting. At first, there might be a lot of distrust among the crew members. After all, they've been fighting against marines for a long time. But if the marine has a strong sense of justice that aligns with Luffy's own view of right and wrong, they could gradually be accepted. For example, the marine might bring in some new combat techniques or knowledge about the navy's operations that could be useful to the Straw Hats.
Naruto's abilities would bring a new flavor to Luffy's crew. His chakra - based powers are different from the Devil Fruits and Haki in One Piece. His healing ability, if he has learned some medical ninjutsu, could be crucial for the crew. Also, his summoning jutsu could call forth some powerful creatures to aid the crew in tough battles. For instance, if he summons a giant toad, it could be used as a distraction or a battering ram against enemy forces.
Naruto's upbeat and positive personality would mesh well with the crew. He and Luffy could become great friends due to their similar energetic natures. Naruto's tendency to be a bit of a goofball would also blend in with the light - heartedness of the Straw Hats.
If Naruto joined Luffy's crew in fanfiction, there would be a lot of interesting interactions. Naruto is used to a world with different kinds of powers like chakra, and in the One Piece world, there's Haki and Devil Fruits. He would have to learn about these new power systems. Also, his relationship with the crew members would be fun to explore. For example, he and Usopp could probably come up with some crazy inventions together, combining ninjutsu and Usopp's gadget - making skills.
In the fanfiction, Hancock could offer her help to Luffy's crew. Given her strength and influence in Amazon Lily, she could provide valuable resources or information. Maybe she'd teach Nami some self - defense techniques she learned in her own island. Also, there could be some romantic tension between Hancock and Luffy that the crew might tease them about.