Robin's character develops through her interactions with the Straw Hat crew. At first, she was more reserved due to her past traumas. But as she spends time with the crew, she starts to open up and trust them more. Her development is also seen in how she becomes more confident in using her abilities to help the crew in their adventures.
In some harem fanfictions, Luffy may develop more emotional intelligence. For example, he has to understand the feelings of the different girls in his harem. He might become more perceptive about relationships compared to his rather straightforward self in the original series.
Naruto could start off as a bit of an outcast in the One Piece world, but as he makes friends with the Straw Hats, he learns to adapt. His development might involve him becoming more understanding of the different cultures and powers in the One Piece universe.
If you like smart and cautious female characters like One Piece Nicole Robin, I can recommend a novel to you: The Fruit of One Piece. The main character of this novel was the historian Nicole Robin. In the story, she showed a similar intelligence and calm personality to One Piece Nicole Robin. She was an outstanding female character. I hope you like my recommendation.
In fanfiction, Luffy's character in Gear 5 might develop a greater sense of responsibility. Since Gear 5 is so powerful, he realizes he has to be more careful about using it. For example, he might avoid using it in areas where there are a lot of innocent bystanders.
Their relationship could start with distrust. Aokiji being a former Marine and Robin being a wanted archaeologist. But as they interact more, they might find common ground in their search for truth. Maybe they start to share stories about their pasts, which slowly builds a bond between them.
Batman becomes more brooding. He's less likely to trust others and more likely to take on dangerous tasks alone.
During time travel, Luffy and Robin might discover new sides of each other. Luffy could see Robin's more vulnerable side when she is faced with historical events that are related to her past and her people. Robin, on the other hand, would be in awe of Luffy's ability to adapt so quickly to any situation in different time periods. This mutual understanding and discovery could lead to a deeper bond between them. They might also share some quiet moments where Robin tells Luffy more about the history she has studied, and Luffy listens intently, strengthening their connection.
Well, often in fanfiction, Luffy's pure - hearted nature brings Nami and Robin closer to him. Nami may be portrayed as more protective of Luffy in these stories, while Robin could be more like a guiding figure for Luffy's growth. For example, Robin might help Luffy understand some complex historical or cultural aspects related to the One Piece world, and Nami could use her navigation skills to lead the crew to places that help Luffy achieve his goals of finding the One Piece.
Robin is crucial in the One Piece novel. Her knowledge of the Poneglyphs makes her a key figure in the search for the One Piece. She can decipher the ancient texts that hold secrets about the Void Century and the true history of the world. This knowledge not only aids the Straw Hat crew in their adventure but also makes her a target for the World Government.
The two novels that I recommend to you are Dragon Soul Creed and One Piece: The Twelve Charm Systems. Both novels have Robin as a character. Among them, the former was a fantasy sword and magic novel, while the latter was a light novel, a derivative doujinshi novel. I hope you like my recommendation. Muah ~