A common theme is her beauty and the effect it has on others. Since she is known for her stunning looks in the One Piece world, many fanfictions play with this aspect, like how characters react when they first see her.
The theme of self - discovery can also be present. Hancock might discover new sides of herself because of her relationship with Luffy. For example, she could become more open - minded or learn to trust others more, which is a big step for her as the empress of Amazon Lily.
Another angle could be a romantic relationship between them. It would be interesting to see how their relationship develops, considering their different backgrounds. For example, Robin's past with the Straw Hats and Hancock's role as a Shichibukai. Their relationship could bring out new sides of their characters that we haven't seen before in the original story.
A big theme is also about breaking barriers. Hancock is a proud and strong woman from Amazon Lily, and Luffy is a carefree pirate. Their relationship in fanfics often shows how they break cultural and social barriers between them. For example, Hancock's tribe has certain traditions and views about men, but with Luffy, she defies some of those. Also, friendship is a theme as Luffy values friendship highly and Hancock becomes part of his circle of friends in a special way.
A possible fanfiction could be about Naruto and Boa Hancock teaming up to rescue their respective friends. Naruto wants to save his comrades from a powerful enemy in the Naruto world, while Hancock aims to free her sisters from the clutches of a new and menacing pirate group. Together, they use their combined strength, Naruto's Rasengan and Hancock's petrifying gaze, to take on their foes and achieve their goals.
One popular type of 'luffy boa hancock fanfiction' often involves their adventures together on the high seas. Writers might create scenarios where Hancock uses her powers to protect Luffy during a difficult battle. Another common plot is about how their relationship develops over time, starting from Hancock's initial infatuation with Luffy and how Luffy, in his own unique way, comes to understand and care for Hancock.
One popular 'Boa Hancock x Luffy' fanfic is 'The Pirate's Heart'. It explores their relationship in an interesting way, with great character development for both. Another one could be 'Love on the Grand Line' which has some really sweet moments between them.
One popular type of Boa Hancock fanfiction is the adventure - based ones. In these stories, Boa Hancock embarks on new quests outside of her usual territory in Amazon Lily. For example, there are fanfictions where she teams up with other One Piece characters to face a new, powerful enemy that threatens the entire Grand Line.
One possible plotline could be that Naruto somehow ends up in the One Piece world and meets Boa Hancock. They initially have misunderstandings due to their different backgrounds, but as they get to know each other, they start to form a bond. Maybe they team up to fight a common enemy that threatens both the ninja world and the pirates' world.
In the One Piece world, Luffy is on this grand adventure and Hancock is a powerful figure. Their relationship has this allure of the unexpected. Fans are drawn to the idea of these two very different characters coming together. Fanfic writers can play with their personalities and create all sorts of interesting scenarios. For example, Hancock's initial haughty attitude towards most people but her special soft spot for Luffy makes for great storytelling. It's also about the idea of love in a world full of pirates and battles, which is quite appealing.