In some 'usopp fanfiction', he might be the key to solving a mystery on the ship. Maybe there are strange occurrences that only his unique perspective and skills can figure out. This could involve his talent for creating gadgets and his sharp observational skills, which are often overlooked by others but prove crucial in these fictional scenarios.
One common theme is empowerment. Since Usopp is often seen as a bit of an underdog, in female Usopp fanfiction, she is often empowered to be a strong and capable character. Another theme is friendship. Just like in the original story, the female Usopp forms strong bonds with her crewmates. Self - discovery is also a theme. She may discover her own abilities and what she truly wants in life through her adventures.
One popular Usopp fanfic might be those that focus on his growth as an inventor. For example, stories where he creates new and amazing gadgets for the Straw Hat crew. Another could be fanfics that explore his relationship with other crew members in more depth, like his friendship with Luffy and how they support each other during tough times.
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.
One idea could be a crossover between Usopp and the world of Harry Potter. Usopp could be a wizard who uses his creativity and skills to create unique magical items and tricks, much like his inventions in his own world. Another could be a crossover with the DC universe, where Usopp teams up with the Green Arrow. They both have skills with ranged weapons and could learn from each other. A third idea is a crossover with the Final Fantasy series. Usopp could find himself in a world full of magic and strange creatures, using his wits to survive and help the characters there.
One common theme is teamwork. Since they are both part of the Straw Hat crew, many fanfictions explore how they work together. For example, in some stories, Usopp uses his inventions to assist Nami in her navigation tasks. Another theme is friendship evolving into something more. Writers often show how their bond deepens over time, starting from a simple crewmate relationship.