Well, there are several places. First, of course, is AO3 as it's very popular among fanfiction writers and readers. There, you can use the search function and type in 'luffy loves robin' to narrow down the results. Also, some smaller One Piece fan communities might have their own collections or links to such fanfictions. You could try searching for One Piece fan forums and see if they have any recommendations or hosting of these types of stories.
Yes, there are likely fanfictions out there with such a plot. Fanfiction writers often explore different character relationships, and the relationship between Robin and Luffy is an interesting one to develop in non - canon stories.
You can try websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, including One Piece, and you're likely to find some great luffy robin fanfiction there. Just use the search function and type in relevant keywords.
Archive of Our Own (AO3) is also a great place. The tagging system there makes it easy to search for specific fanfiction themes. Just type in 'luffy loves nami' in the search bar, and you'll get a list of relevant stories.
You can try fanfiction.net. It has a large collection of One Piece fanfictions, and there's a good chance you'll find some stories about Hancock's love for Luffy there.
You can try looking on fanfiction websites such as Archive of Our Own (AO3) or FanFiction.net. They usually have a wide range of fanfictions including ones about Blackfire loving Robin.
Another option could be Tumblr. Some users create and share their own luffy robin fanfic on their blogs. You can search for relevant tags like #luffyrobinfanfic or #OnePiecefanfic to find some interesting reads.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). It has a large collection of One Piece fanfictions, and you're likely to find a good number of 'luffy x nami x robin' ones there. Just use the search function and type in the relevant tags.
Fanfiction.net is another great place. There are many different categories and you can narrow it down to the One Piece section and then look for works specifically about Robin and Luffy's love. However, the quality may vary so you might need to read a few to find the really good ones.
One possible plot could be that Robin realizes her feelings for Luffy during a particularly dangerous adventure. Maybe they get separated from the crew, and in the time they are alone, she sees a different side of Luffy and her feelings start to change.
One popular luffy loves robin fanfiction might be 'The Unspoken Bond'. It delves into their relationship in a really sweet way, showing how Luffy's carefree nature complements Robin's more reserved personality. Another could be 'A New Adventure for Two' which takes them on a journey where their feelings for each other start to surface in unexpected ways. And there's also 'Love in the Grand Line' that explores their connection against the backdrop of the Straw Hat Pirates' various escapades.