Perhaps in this fanfiction, Naruto is on a mission in his own world when a strange portal opens and leads him to the One Piece universe right where Robin is. At first, they are both cautious of each other. But as they learn about their respective powers and goals, they decide to join forces. Maybe there's a common enemy that is threatening both the ninja world and the pirate world, and together they strive to defeat it.
It could be a powerful ninja from Naruto's world who has turned evil and has found a way to travel to the One Piece world. He wants to use the power of the Devil Fruits and the ancient secrets Robin knows to take over both worlds.
Expect a lot of character exploration. Since Robin has a complex past and Zoro has his own goals and dreams, the fanfiction could delve into how they influence each other. For example, Zoro's pursuit of becoming the world's greatest swordsman might inspire Robin to pursue her own academic or personal goals more vigorously.
In Robin x Zoro fanfiction, their relationship can be really interesting. Robin is the intellectual and mysterious one, while Zoro is the strong and determined swordsman. Their interactions might start from a simple comradeship on the Straw Hat crew. Maybe in some fanfictions, Robin's knowledge could help Zoro in his swordsmanship journey, like providing him with historical information about some special swords or fighting techniques from the past.
A very creative one is 'When Worlds Collide: Naruto and Robin'. This fanfiction imagines a scenario where the entire One Piece crew gets teleported to the Naruto world. Robin stands out as she tries to understand the new world's ninja techniques and at the same time, help the Naruto characters understand the value of the One Piece world's treasures and knowledge. It has a lot of action and character development.
Many 'One Piece Robin x OC fanfiction' works explore the theme of acceptance. The OC, being an outsider in the One Piece world, has to be accepted by the characters, especially Robin. And Robin, with her own past, also has to accept the presence of this new character in her life. There's also the theme of growth, both in terms of power and character, for both Robin and the OC as they interact and go through various experiences together.
One common theme is adventure. Since they are part of the Straw Hat crew in One Piece, fanfictions often put them in new and exciting adventures together. Another theme is growth. Luffy and Robin both grow as characters, and fanfictions explore how they influence each other's growth. For example, Luffy's optimism might help Robin overcome her past traumas.
One of the main things that make it appealing is the opportunity for crossovers. Fans love to see how characters from different shows would interact if they were in the same world. Robin in Naruto fanfiction can be a bridge between the two worlds. Her unique abilities and personality can lead to unexpected plot twists. For example, she could use her knowledge of ancient texts in One Piece to help solve some mystery in the Naruto world. And seeing Naruto and his friends react to her and her abilities is really fun.
I like the storylines where Robin forms deep friendships in the fanfictions. In one, she befriends a group of scholars on an island. They exchange knowledge and she helps them protect their research from pirates. It's a great display of her character values. There are also storylines that explore her relationship with the other Straw Hats in new ways, like how she teaches Usopp about ancient plants.
There could be a fanfiction where they both participate in a grand pirate tournament. They enter as a team, facing off against other powerful pirate duos. In the process, they show off their combined combat and strategic abilities. Robin can manipulate the environment to their advantage while Nami creates weather - based distractions for their opponents. This not only showcases their skills but also their growing trust and cooperation.