The plot could revolve around a curse that was placed on them during one of their adventures. This curse made them pregnant. Zoro and Tashigi would then have to team up to find a way to break the curse. Along the way, they might discover secrets about each other that they never knew before. For example, Zoro might learn more about Tashigi's past and her dreams outside of being a marine. And Tashigi could understand Zoro's loyalty to his crew on a deeper level. Their journey to reverse the pregnancy could also lead them to new and unknown parts of the One Piece world.
One possible storyline could be that they accidentally got a magic spell cast on them which made them pregnant. In this fanfiction, they would have to figure out how to deal with this unexpected situation while still being part of the Straw Hat crew. Maybe they'd struggle to keep up with their pirate duties at first, but then find ways to adapt and still contribute to the crew's adventures.
One possible plot could be that they are on a new island during their adventures in One Piece. Since they are pregnant, the crew has to be extra cautious. Zoro might struggle with the idea of being a father as he has always been focused on his swordsmanship. He could start training in a new way to protect his future family. Robin, on the other hand, would use her knowledge to ensure a safe pregnancy. She might research about any potential threats to the babies from the various historical texts she has access to. The crew would also rally around them, with Sanji cooking special nutritious meals for the expecting parents.
Their relationship would likely become more complex. Zoro, who is usually focused on his swords and his crew, would have to start thinking about someone else. Tashigi, as a marine, would also have to reevaluate her priorities. They might start to rely on each other more, sharing their fears and hopes for the future. For example, Zoro could offer Tashigi protection in a more personal way than before, and Tashigi could give Zoro advice on how to deal with the upcoming changes in his life.
Well, fans are drawn to the idea of these two characters getting together because it represents a sort of forbidden love. In the One Piece world, pirates and marines are on opposite sides. So, seeing Zoro and Tashigi's relationship develop despite that is really exciting for many fans. Also, both characters have their own charm. Zoro's cool and powerful, and Tashigi is strong - willed and determined. Their combination makes for great fanfiction material.
Perhaps in the fanfiction, Nami's pregnancy is a result of some magical or cursed event. The crew then has to search for a way to either reverse it if Nami wishes so, or to ensure a safe pregnancy and birth. Along the way, they encounter different islands with unique cultures related to pregnancy and childbirth, and Nami learns a lot about motherhood from these experiences.
Nami, on the other hand, would be more practical. She'd likely start planning for the future, like making sure they have enough resources on the ship for the baby. She'd also be thinking about how to balance being a mother with her role as a navigator in the Straw Hat crew. She might draw up detailed plans for the baby's living space on the ship and start thinking about teaching the child about navigation early on.
One great 'One Piece Zoro x Tashigi fanfiction' is 'The Unlikely Bond'. It delves into their relationship in a very interesting way, exploring how their opposing views on justice could actually bring them closer. It has some really well - written dialogue that captures their personalities.
One common theme is the rivalry. Since they are both sword - wielders, there's often a sense of competition between them in fanfictions. Another theme is the idea of redemption. Tashigi has a strong sense of justice and sometimes in the stories, Zoro might be seen as a bit of a wild card, and she tries to 'redeem' him in a sense.
A plot for this fanfiction could be that Robin and Zoro keep the pregnancy a secret from the crew at first. But as time goes on, it becomes harder to hide. Meanwhile, they are also facing a new island with strange customs and threats that are related to Robin's pregnancy in some way. For example, the island has a law that pregnant women must perform a certain ritual, and if they don't, something bad will happen to the baby.
One possible plot could be that Naruto is somehow transported to the One Piece world. Zoro, seeing Naruto's potential and his own experience in training, decides to take Naruto under his wing. Zoro might start by teaching Naruto basic swordsmanship, which Naruto initially struggles with as he is used to his ninjutsu. But gradually, Naruto starts to incorporate his own chakra control into the sword techniques, creating unique attacks. They could also go on adventures together in the One Piece world, facing pirates and other threats, all while Naruto is constantly learning from Zoro's strict and disciplined training methods.