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.
First, know Usopp's character well. His traits like being a bit of a coward but also very brave when it counts, his love for inventing, and his loyalty to the crew. Then, come up with an interesting plot. It could be something like Usopp having to save the day with one of his inventions when the crew is in a tight spot. Also, make sure to keep his unique speaking style in mind when writing his dialogue.
One idea could be that Sanji and Usopp team up for a cooking competition on the ship. Sanji brings his world - class cooking skills and Usopp uses his creativity to come up with unique presentation ideas. Another could be a situation where they get lost on an island together and have to rely on each other's skills, Sanji for survival cooking and Usopp for building shelters and creating distractions against potential threats.
Begin by deciding on the setting. It could be on the Thousand Sunny, during a battle, or on a new and strange island. For example, if you set it on the ship, you can start with Sanji cooking in the kitchen and Usopp coming in to ask for a snack. Their conversation can then lead to an adventure idea. Also, consider their goals. Maybe Sanji wants to create a new dish and Usopp wants to test his latest invention, and these two things somehow intertwine to start the fanfic story.
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.
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.