Luffy from One Piece would be an obvious choice. Their relationship in the original One Piece story is already complex and full of potential for more exploration in a crossover fanfiction. They could team up in a different universe or be forced to fight against each other in a strange new setting.
One popular type of OC is a female pirate who is as strong - willed as Katakuri. She challenges him in a battle of wits and strength, and their interactions create a lot of tension and intrigue in the fanfiction. For example, she might try to steal a precious treasure that Katakuri is guarding.
A magical healer could be a great ally. Since Zoro often gets injured in battles, the healer can patch him up. Also, the healer might be able to use magic to enhance Zoro's physical abilities for a short time, like making his strikes faster or stronger.
It's hard to say for sure. Katakuri's strength and abilities depend on various factors, and the outcome could be influenced by the circumstances of the battle.
One character that would fit well is Robin. Her knowledge of the world and its secrets could be relevant if there's some mystery involved in the Zoro - Mihawk relationship. Brook, with his unique personality and his own skills as a swordsman, could also be included. He could have some interesting conversations with Zoro and Mihawk about swordsmanship. And Shanks, as a great swordsman himself and a significant figure in the One Piece world, could potentially play a role in the story, perhaps as an old acquaintance of Mihawk.
Another theme is character adaptation. Katakuri has to adapt to new environments, cultures, and rules in crossover fanfics. This can lead to some really interesting character development. For instance, in a crossover with a post - apocalyptic world, he might have to change his moral code to survive. This theme is important as it shows different sides of Katakuri's character.
The character interactions are quite special. For example, Naruto's positive and energetic nature contrasts with Katakuri's more reserved and powerful presence. Writers often use this contrast to create interesting dialogues and plot developments in the fanfiction.
Another theme is the exploration of an unlikely relationship. Katakuri is a unique character, and the idea of him being in a relationship with an ordinary reader is an interesting concept. Fanfictions often explore how they bridge the gap between their different worlds. It could be about the reader learning about Katakuri's world of pirates and vice versa.
One idea could be a story where a new character, the OC, is a young chef who idolizes Katakuri. They enter a cooking competition in the Big Mom Pirates' territory and Katakuri takes notice. The OC tries to prove themselves worthy of his respect through their cooking skills.
One great Katakuri x OC fanfiction is 'A Sweet Encounter'. In this story, the OC is a baker who stumbles into Katakuri's world. The author does an amazing job of building their relationship gradually. It shows how the OC's kind nature starts to break through Katakuri's tough exterior. Another interesting one is 'The Unlikely Bond'. Here, the OC has a special power that intrigues Katakuri, and they form a bond while facing common enemies.