One common trope is the 'fish out of water' situation. The OC, being new to Chopper's world, might struggle to adapt to the strange and often dangerous pirate life. For example, they could be shocked by the battles and the rough nature of the crew at first. Another trope is the 'healing relationship'. Chopper, being a doctor, could heal the OC not just physically but also emotionally, and in turn, the OC could help Chopper grow in confidence and understanding of human relationships. There's also the 'adventure buddies' trope where they go on various adventures together, facing challenges side by side and relying on each other's unique skills.
First, you need to create your OC. Decide on their appearance, personality, and backstory. For example, if your OC is a shy artist, think about how they got on a pirate ship. Then, think about the relationship with Chopper. Maybe they meet when Chopper is looking for medicinal herbs and the OC is painting in the forest. Next, plan out a simple plot. It could be as basic as the OC getting lost on an island and Chopper helping them find their way back to the ship.
Growth is a prevalent theme. Chopper, as a character, is constantly evolving, and Robin plays a role in that in these fanfics. They also often have themes of discovery. Whether it's exploring a new island or uncovering a mystery, they do it together. Their relationship is at the center of these stories, and the exploration of their different personalities is also a common aspect. For instance, Chopper's innocent and curious nature against Robin's more reserved and intellectual one makes for interesting interactions.
One common theme is friendship. Luffy and Chopper have a very special bond in the original series, and fanfics often explore and expand on that. They might write about how they support each other during tough times on their adventures.
Well, 'chopper fanfic' is basically fan - made stories that revolve around the concept of 'chopper'. If 'chopper' is a vehicle, like a motorcycle (which is often called a chopper), then the fanfic could be about cool rides, customizations, or races involving these choppers. It all depends on what the 'chopper' in question represents in the context of the fanfic.
It depends on the fan community. If 'chopper' is related to a niche interest like a specific type of custom motorcycle, then within that small but passionate community, there might be some fanfics that are considered popular. These could be stories about building the ultimate chopper or tales of chopper - related road trips that resonate with the members of that community.
One great 'chopper x robin fanfic' could be 'Chopper's Adventure with Robin'. In this fic, Chopper and Robin go on an archaeological exploration together. It's full of their cute interactions as Chopper's naivete contrasts with Robin's wisdom. Another might be 'Chopper and Robin: A Bond Beyond'. This story focuses on how they help each other during tough times on the ship. It shows their growing bond and mutual understanding.
Often, it emphasizes their friendship. Nami's feisty and smart nature combined with Chopper's innocent and helpful self makes for interesting interactions. For example, in some fanfics, Nami uses Chopper to get out of tricky situations with other crew members by pretending he needs her help immediately.
You can try fanfiction websites like Archive of Our Own (AO3). There are often a lot of fanfics about Luffy and Chopper there. Just use the search function and type in 'Luffy x Chopper' to find relevant works.