First, they could start with a mutual interest in knowledge. Robin loves to study history, and if the OC has some special knowledge or a thirst for knowledge as well, that can be a starting point. For example, if the OC discovers a new type of Poneglyph and brings it to Robin's attention.
One idea could be that the OC is a new pirate who joins the Straw Hats. Over time, they develop a special bond with Nico Robin due to their shared interest in ancient history. Meanwhile, during an encounter with Boa Hancock, the OC manages to gain her respect in an unexpected way, like saving her from a new threat in the Grand Line. This could lead to a complex love triangle where the OC has to navigate their feelings for both strong - willed women.
The theme of growth is quite prevalent. The oc might start off as a weak or inexperienced character and through their interactions with Robin, grow in strength and knowledge. Romance is also a common theme. Writers often explore the relationship between the oc and Robin, from the initial attraction to a full - blown love story. Additionally, the theme of redemption can be found in some fanfics. Maybe the oc has a troubled past and Robin helps them find a new path in life.
Many 'One Piece Robin x OC fanfiction' works explore the theme of acceptance. The OC, being an outsider in the One Piece world, has to be accepted by the characters, especially Robin. And Robin, with her own past, also has to accept the presence of this new character in her life. There's also the theme of growth, both in terms of power and character, for both Robin and the OC as they interact and go through various experiences together.
In a good Fire Emblem Robin x OC fanfiction, the OC should be well - developed. They should have their own goals, fears, and personality. The relationship between Robin and the OC should grow and change over the course of the story. It should be more than just a simple romance. There should be some sort of conflict or challenge that they face together, whether it's against an enemy in battle or some internal struggle within the characters themselves. This makes the story more interesting and engaging.
One common plot element is the oc having a special ability or knowledge that intrigues Robin. For example, the oc might be an expert in ancient languages, which catches Robin's attention as she has her own interest in history and archaeology.
The combination of an original character (OC) with Nico Robin in a harem setup is interesting because it allows for a lot of creative freedom. Writers can create unique personalities for the OC that either complement or contrast with Robin's character, leading to interesting interactions.
First, you need to develop your OC well. Give them a unique backstory, personality traits, and goals. For example, if your OC is a chef, their cooking could be a way to bond with Nico Robin (maybe she loves a certain dish) and Boa Hancock (by impressing her with a special recipe). Also, understand the personalities of Robin and Hancock. Robin is calm, intelligent, and has a dark past, while Hancock is proud, strong, and has her own insecurities. Incorporate these into how your OC interacts with them.
Adventure is a very common theme. Since Nami and Robin are part of the Straw Hat crew in One Piece, many fanfictions involve the OC joining them on their adventures in the Grand Line. For example, they might go on a quest for a lost treasure or to discover a new island.
There are various oc x nico robin fanfics out there. One way to find them is to join One Piece - related fan forums. Fans often share and discuss their favorite fanfics in these communities. A great fanfic might be one where the oc has a unique power or background that intertwines with Robin's story and knowledge. For example, an oc who is also a historian could have really interesting interactions with Robin as they both uncover secrets about the Void Century.