It could be Chopper. Since Chopper is a doctor and Reiju has some medical knowledge, they might bond over sharing medical techniques and treating the crew's injuries. Also, Chopper's kind - hearted nature would make him a great friend for Reiju who might be used to a more cut - throat family environment.
If Naruto was raised by the Straw Hats, he'd probably be a very different person. He might be more carefree like Luffy. For example, he'd be used to the wacky adventures on the Grand Line. His ninja skills could blend with the pirates' combat styles, creating some really unique fighting techniques.
His personality would become more outgoing and adventurous. The Straw Hats' lifestyle is full of exploration, so Naruto would be more eager to take risks.
Well, as of the latest manga chapters, Yamato has indeed become a part of the Straw Hats. This decision brings new dynamics and adventures to the crew.
At first, not very well. The Straw Hats have had bad experiences with Marines. They might see the Marine OC as a potential threat. However, if the OC shows that they are different from the typical corrupt Marines, like by helping the crew out of a tough situation right away, they might start to be more accepting.
Well, Naruto's ninja skills would blend in an exciting way. His speed and agility from being a ninja would be useful during battles at sea or on islands. The Straw Hats are all about teamwork, and Naruto's experience in team battles in the ninja world would add to that. His Nine - Tails chakra, if he could control it well, might give the Straw Hats an edge in really difficult situations. He could also use his transformation jutsu for undercover work or just for fun with the crew.
If Smoker joins the Straw Hats in fanfiction, the development might be slow. At first, he would struggle to fit in with their laid - back and often rule - breaking ways. But his sense of justice could lead him to find common ground. For example, he might see that the Straw Hats are fighting against corrupt forces, just in a different way than the Marines. As the story progresses, his character could evolve. He might start to see the world from the Straw Hats' perspective and become more accepting of their methods. This would not only change him but also affect how the Straw Hats view the Marines in general.
I really like the fanfiction where the Straw Hats time travel to the future. In this story, they see how their actions have affected the world in the long run. It shows a post - apocalyptic world that was caused by a series of events that they were unknowingly a part of. It makes them reflect on their current actions and how they can change things for the better. Another good one is the one where they go back to the time of Gol D. Roger. They get to meet the legendary pirate and learn some of his secrets, which is really exciting for fans of the series.