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.
In the past, Usopp's abilities like his slingshot skills might be seen as more primitive compared to the advanced weaponry in his own time. But his creativity could give him an edge. For example, in a time when there were less advanced long - range weapons, his slingshot could be a very unique and effective tool. In the future, if he travels there, his abilities might seem obsolete at first. However, he could adapt by using his knowledge of old - fashioned combat and combine it with the new technology he finds.
To develop their relationship realistically, start with their existing friendship. Sanji often cooks for Usopp, so that could be a basis. Maybe Usopp starts to notice small things about Sanji, like how he cares for the crew through his food. And Sanji could see Usopp's growth in courage, which makes him respect Usopp more. From there, small moments of shared glances, and a bit of blushing when they accidentally touch could start to build the relationship.
Perhaps there's a mission where Sanji and Usopp have to go undercover as a couple in a high - society event. At first, it's just for the mission, but as they play their parts, they start to feel real emotions. They have to navigate through the social intrigue, all while dealing with their own growing feelings for each other. This situation could lead to a lot of cute and romantic moments in the fanfiction.
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.
One kaya ghost story could be about a haunted kaya tree. Legend has it that at midnight, a white figure can be seen wandering around the tree. It's said to be the spirit of a young girl who died near the tree long ago.
I recommend One Piece: The Great God Usopp to you. This book is a story about Usopp. It tells the story of how he obtained the League of Legends system through an accidental transmigration and became invincible. If you want to read a One Piece Doujinshi novel with a deceptive cloth as the main character, this book is perfect for you. I hope you will like my recommendation.