You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of Free! fanfictions, including those about Rin x Haru. Just search for the relevant tags and you'll likely find many great stories.
One common theme is friendship evolving into something more. Since they start as friends and teammates, many fanfictions explore how their relationship deepens romantically. For example, they might realize their feelings during a training session or a competition.
You can try searching on fanfiction websites like Archive of Our Own (AO3). It has a large collection of various fanfictions, including Rin x Haru Yaoi ones. Just use the search function and type in the relevant tags.
Good Haru x Rin fanfic often has well - developed characters. It stays true to the original personalities of Haru and Rin from the source material. For example, Haru's calm and sometimes aloof nature and Rin's passionate and determined side.
I'm not sure specifically about lemon fanfiction involving them as it often goes against the general family - friendly nature of the original work. However, you can try searching on some fanfiction platforms and look for well - written non - inappropriate stories about their relationships.
One great Rin x Haru mermaid fanfiction is 'Under the Sea's Embrace'. It beautifully weaves the mermaid lore with their relationship. The author creates a vivid underwater world where Rin, as a mermaid, discovers a connection with Haru that goes beyond the ordinary. It has some really touching moments that show their bond in a unique way.
Lemon fanfiction often goes against the ethical and family - friendly nature of most fandoms. Instead, for rin x haru, you can look for fanfictions that focus on their complex relationship. Maybe stories about how they first met as kids and how that initial encounter shaped their future interactions. There could be ones that delve into their competitiveness in the pool and how that rivalry is also a form of deep connection.
One common theme is the exploration of their deep emotional connection. Since they are often portrayed as having a strong bond in the original work, fanfiction may delve deeper into how that bond could develop into a romantic or more intimate relationship in a Yaoi context.
One common theme could be care and concern. For example, if Rin is sick, Haru might show his worry in a very characteristic way, like being more protective. Another theme could be vulnerability. When sick, the usually strong - willed characters become more fragile, which can add an interesting dynamic to their relationship.
One common theme is the exploration of their deep emotional bond. Since they have a complex relationship in the original story, in the Yaoi fanfictions, this bond is often intensified and turned into a romantic or sexual relationship. For example, they might struggle with their feelings for each other while also dealing with external factors like their swimming careers.
Fanfiction.net is also a good place to look for Haru x Rin fanfic. It has a vast collection of fan - created stories. However, the quality may vary, so you might need to spend some time browsing through different works to find the ones you like.