The theme of family is often present. The OC could be like a surrogate family member to Regina, filling a void in her life. Also, the theme of self - discovery. As Regina interacts with the OC, she discovers new things about herself, her capabilities, and her desires. This is often a very engaging aspect of Regina Mills OC fanfiction.
Another common theme is power and its consequences. Regina has had a complex relationship with power throughout the show. Fanfictions often explore how she continues to deal with power, whether she tries to regain it, use it for good, or completely shun it. This theme allows for a lot of interesting character exploration and plot development.
One common theme is the exploration of Regina's character development during pregnancy. It could show how she deals with the physical and emotional changes.
One common theme is family protection. Since they live in a dangerous world, a lot of fanfics focus on how they will keep their baby safe from all the threats around them. For example, from villains who might want to use the baby for power.
Power dynamics can be a significant theme as well. Regina is a powerful character, and the reader might be an ordinary person or someone with their own form of power. The fanfics may explore how they interact in terms of power - whether the reader is intimidated by Regina's power, or if they find a way to balance it in their relationship. Additionally, self - discovery is often a theme. As the relationship between Regina and the reader develops, both characters may learn more about themselves, their desires, and their limits.
In fanfiction, their relationship can be very complex. Often, Regina is portrayed as a mother who is trying her best to make up for past mistakes. Henry, on the other hand, is sometimes shown as the one who helps Regina see the good in herself. Their relationship can be a journey of forgiveness and growth.
One popular theme is power struggles. Since Regina Mills is a powerful character, when she is crossed over into other universes, there are often power dynamics at play. For example, in crossovers with other magical universes, she might have to compete or cooperate with other powerful entities.
There's 'Regina Mills and the Unlikely Ally'. In this fanfiction, the OC is a magic user from a far - off land. The story is engaging as it shows how Regina has to deal with this new person in her town. It has some great plot twists and really delves into Regina's character.
A theme that often comes up is redemption. If the OC has a troubled past or has made mistakes, they might find redemption through their relationship with Henry. Henry, with his pure heart and his role in the story, can be a catalyst for the OC's change. Additionally, the exploration of different timelines or alternate universes is common, where the relationship between Henry and the OC can be very different from what we see in the original show.
Romantic relationships between them are also a common theme. Many fans ship Regina and Emma, and fanfictions explore their potential romantic connection. These stories often deal with the challenges they might face in a relationship, given their complex personalities and pasts, which makes for some really engaging and emotional reads.
I'm not sure if there are a huge number specifically named 'lemon' fanfictions about Regina Mills and Henry Mills as that's not a very common or appropriate theme for their relationship given it's a mother - son type bond in the original context. However, if you're looking for general positive fanfictions about them, 'Henry's Guide to Regina' is interesting. It shows Henry helping Regina to better understand the modern world and in the process, their relationship grows stronger.