Friendship turned to more is a very common theme. Since they start as crewmates with a normal friendship in the original, fanfictions often explore how that can develop into a romantic or deeper emotional bond.
One great Zoro x Usopp fanfiction is 'The Unlikely Bond'. It beautifully explores their friendship evolving into something more. The author does a wonderful job of depicting Zoro's tough exterior softening towards Usopp, and Usopp finding new courage in Zoro's presence.
In a fanfiction, Usopp could get sick from a cursed item they found on an ancient ruin. This sickness slowly drains his energy and his ability to tell lies (which is a big part of his character). Luffy, not fully understanding the severity, tries to cheer Usopp up in his own goofy way. Zoro might be more practical and keep a lookout for any enemies who might take advantage of Usopp's weakened state. Chopper, of course, is desperately trying to find a cure, but is facing difficulties due to the unknown nature of the curse.
Some of the top novels from the Regency era include 'Pride and Prejudice' by Jane Austen. It's a story full of love, misunderstandings, and social commentary. The characters are vivid and the relationship between Elizabeth and Mr. Darcy is iconic.
The female lead of "Love on the Road" was a lost direction, but she was also a female lead who was both a confused lady and a designer. She met a big shot in the industry, Mr. Xing. Their love story was a little interesting, full of sweetness and humor. I'll recommend it to you. I hope you like my recommendation. Muah ~
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.
Artificial rain suppression was a method to stop the rain in advance. By carrying out artificial rain enhancement in the upper reaches of the rain cloud, it could accelerate the energy spread of the weather system, causing the water droplets in the air to form and land on the ground in advance, thus stopping the rain in advance. However, the effect of artificial rain dissipation was still unclear. Therefore, the most feasible way to stop the rain was to rely on natural phenomena and climate change.
Perhaps a plot twist could be that a long - lost relative of either Zoro or Sanji shows up to object to the marriage. This relative could have some old grudge or a different plan for their family member. It would create a lot of drama and conflict. They would have to fight against this external force while also dealing with their own feelings for each other. Zoro would probably be more straightforward in facing the relative, while Sanji might be more conflicted between family loyalty and her new relationship with Zoro.