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.
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.
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.
One possibility is that they gain a deeper understanding of Luffy's motives. For example, they might see his memories of making the promise to Shanks and realize how important it is for him to become the Pirate King. This could strengthen their resolve to support him even more.
Well, one possibility is that Reiju could bring her unique skills like her combat abilities or her knowledge of certain technologies to the Straw Hats. Maybe she joins them to seek adventure away from her family's influence. She could also form interesting relationships with the crew members, for example, having a sister - like bond with Nami due to their shared intelligence in different areas.