Another concept is the exploration of different worlds within One Piece. If an admiral crosses over to a less - known or mysterious island, it can open up new storylines. Maybe they discover ancient secrets or new types of Devil Fruits. This can bring a fresh perspective to the One Piece universe as a whole.
Well, the character development is a big part. In these crossovers, admirals might find themselves in situations that force them to change their views. Like if they are paired with a more morally gray character from another part of the One Piece world. They could start to question their strict sense of justice. This adds a whole new layer to their personalities.
One interesting concept is a crossover with other popular anime like Naruto. Imagine Luffy and Naruto teaming up, it would be a clash of two very different power systems and personalities. Another concept could be a crossover with a superhero universe. For example, Luffy meeting Superman. Their powers are so different, it would make for an exciting story.
Well, a really cool concept is the idea of One Piece pirates learning magic. Imagine Zoro trying to master spells instead of sword techniques. It would be a hilarious and interesting twist. Also, the idea of Hogwarts students being interested in the One Piece world and its treasures. They might see the One Piece as a sort of ultimate magical artifact that they want to discover.
You could also explore an OC Admiral who is a bit of an outlier in the Navy. Maybe they have a more lenient view on pirates and believe in reform rather than just punishment. This would create a lot of internal conflict within the Navy and interesting interactions with the Straw Hat crew when they cross paths.
One interesting concept is alternate universe stories. For example, what if Luffy didn't eat the Gum - Gum Fruit but a different Devil Fruit? Another concept could be character backstories that are expanded or changed. Maybe a fanfic delves deeper into Sanji's time at the Baratie and creates new relationships or events during that period. Also, there are fanfictions that explore different power - up scenarios for the characters, like if Zoro found a new type of sword with unique abilities.
Aokiji is popular too. His more laid - back approach to justice compared to Akainu makes him a great character for crossovers. He can form interesting relationships with other characters, and his ice - based powers can be used in creative ways in different crossover scenarios.
One interesting concept could be a character being reborn with knowledge of future events in the One Piece world. For example, they might know about the true nature of the One Piece treasure before the main characters do, which could lead to a whole new set of adventures and interactions. Another concept could be a reborn character having a different Devil Fruit ability than in their previous life, changing the power dynamics in the story.
Well, in One Piece system fanfiction, a common concept is the creation of new Devil Fruits. Imagine a Devil Fruit that gives the user the ability to control time in a limited way. This could completely change the power dynamics in battles. Also, some fanfictions explore different alliances among the characters. For instance, Zoro and Sanji might form a temporary alliance with a new character to take on a powerful enemy that they couldn't defeat alone.
One interesting concept could be the idea of Pokemon existing in the One Piece world. For example, trainers in the Straw Hat crew. Luffy might befriend a really strong and unique Pokemon, like a Pikachu with a Conqueror's Haki ability. It would add a whole new dynamic to their adventures as they explore the Grand Line.
One interesting concept could be the reincarnation of a character into a different era in the One Piece world. For example, a character from the past reincarnating during the Straw Hats' time. This could lead to unique interactions and plot developments as they might have knowledge from their past life that could change the course of events. Another concept could be the reincarnation of a powerful villain, but with a different personality or goal, which would add a new layer of complexity to the story.
Well, in some One Piece Law fanfiction, there are concepts about Law's devil fruit powers. Writers might come up with new and creative ways he can use the Ope - Ope no Mi. For example, not just for medical purposes or combat, but perhaps for some unique forms of transportation or even creating alternate dimensions within his Room ability.