Another theme is friendship - turned - love. Since they were friends in the original story, fanfictions might show how their platonic relationship gradually evolves into a romantic one. This could involve them realizing their feelings during their time at Hogwarts, perhaps through shared experiences like studying for exams or facing a common enemy.
The 'enemies to lovers' trope can also be found. Maybe Logan initially dislikes Remus' unruly behavior, but over time, they develop feelings for each other. There's also the 'roommate' or 'forced proximity' trope, which can lead to all kinds of interesting interactions and relationship developments between them.
One common theme is acceptance. Since Remus is a werewolf, often in these fics the OC has to come to terms with his condition and accept him for who he is. For example, in many stories, the OC may initially be scared but then grows to love all of Remus, including his lycanthropy.
One popular theme is their courtship at Hogwarts. It often includes James trying to impress Lily with his Quidditch skills or his academic achievements. Another theme is their friendship with the Marauders and how that affected their relationship. For instance, Sirius and Remus might play matchmaker for them.
The theme of redemption and acceptance through their relationship is also seen. Sirius has his own troubled past, and Remus has his insecurities. In the 'lemon' fanfictions, their physical intimacy can be a way of them accepting each other fully, flaws and all, and finding solace and love in each other's arms.
You can try websites like Archive of Our Own (AO3). It has a large collection of fanfictions, and you can search for 'Remus x Lily' specifically. There are often filters to help you find the most relevant and well - rated ones.
There's a fanfiction where Asta and Lily discover a hidden magic that only they can control. In this story, their friendship blossoms into something more as they train to master this new power. It's filled with action scenes as they fight off those who would try to steal their newfound magic.
One common theme is the exploration of the characters' darker natures. For instance, Remus's struggle with his werewolf form can be depicted in a much more sinister light, perhaps with him having less control. Another theme could be the distortion of relationships. Maybe Sirius becomes more distrustful of his friends due to some dark influence.
One common theme is acceptance. Remus has to accept his own identity as a werewolf and Tonks has to accept the challenges that come with loving him. For example, in many fanfictions, Remus is initially hesitant about being with Tonks because of his condition.
One common theme is discovery. As Sayuri and Remus come from different backgrounds, they often discover new things about each other and themselves. For example, in many stories, Sayuri discovers Remus's hidden courage.
One popular theme is the exploration of their different personalities. Remus, with his quiet wisdom, and Harry, full of youthful determination. Another theme could be the power dynamics, as Remus is an older, more experienced wizard and Harry is still learning. Also, the idea of forbidden love due to their different generations and the wizarding world's expectations.