A frequent theme is acceptance. The OC has to be accepted by the different characters in the harem, and also has to accept them in return. Also, adventure can be a theme, as they might go on adventures together as a group.
One common theme is self - discovery. The OC often discovers more about themselves as they interact with the members of the harem. Another theme is friendship, as the relationships in the harem are not just romantic but also based on friendship.
The theme of growth is quite common. The OC grows in character, learning from the experiences with the harem. And there's also the theme of love in different forms, not just romantic love but also platonic love among the characters in the harem.
The theme of acceptance is also prevalent. The OC may be different from the regular ponies in Equestria, and the members of the harem have to accept the OC for who they are. Also, adventure is a common theme. The OC and the harem often go on adventures together, which helps to strengthen their relationships and also provides exciting plot points. They might be exploring new parts of Equestria or facing off against villains together.
Friendship is a common theme. Since My Little Pony is all about friendship, in these fanfics, the OC forms friendships with the members of the harem which often develop into something more. Another theme is self - discovery. As the OC navigates this new world and relationships, they learn more about themselves.
One common theme is the exploration of different relationships. Since it's a harem concept, there's often a focus on how the human character interacts with multiple pony - like characters romantically or platonically. Another theme is the adaptation of the MLP world to fit human elements, like how human values and pony values mix or clash.
One common theme is self - discovery. Since the oc alicorns are often new characters in the MLP universe, they usually go through a process of finding out who they are and what their purpose is. Another theme is friendship, just like in the main MLP series. The oc alicorns form bonds with other ponies and learn valuable lessons about loyalty and kindness.
One common theme is acceptance. Griffon OCs often face the challenge of being accepted in a pony - dominated world, like in 'The Griffon Among Ponies'. Another theme is self - discovery. As the Griffon OCs go through different experiences, they learn more about themselves, such as in 'The Griffon's Adventure'.
One common theme is acceptance. Since Draconequus OCs are often different from the regular ponies in MLP, many fanfictions explore how they are accepted or not by the pony community.
Friendship is also a big theme. Just like in the main My Little Pony series, the female alicorn OCs form friendships with other ponies. These friendships help them through tough times and are a source of support. In some fanfictions, the OC might be an outcast at first, but through friendship, they find acceptance.
Another theme is self - discovery. The OC usually has some sort of journey where they learn more about themselves, and Luna also often discovers new aspects of her personality or her role in Equestria through her interactions with the OC. For example, in some fanfictions, Luna realizes she can be more approachable through her time with the OC.
Another theme is self - discovery. The dragon OC usually has to figure out who they are and what their place is in the world. They might struggle with their identity as a dragon in a pony - dominated world, and the story is about them finding their true self. This can involve learning about their powers or their heritage.
One common theme is the idea of being an outcast. Since bat ponies are often different from the regular ponies in MLP, they are sometimes depicted as outcasts in fanfiction, having to prove their worth.