Often, the theme of growth is present. As the story progresses, both Kara and the female oc grow as individuals. Their relationship also matures. And sometimes, there's a theme of finding a place in the world. The female oc, especially if she's new to Kara's world, has to figure out where she belongs, with Kara's help or on her own.
There's also 'Kara and the Mysterious Oc'. In this fanfiction, the female oc has a mysterious past that Kara gradually uncovers. The story is filled with suspense and heart - warming moments as they grow closer and learn from each other.
First, understand the characters well. Kara is kind - hearted and protective, so your OC should interact with her in a way that makes sense for her personality. For example, if your OC is more brash, there could be some initial conflict that then develops into a deeper connection.
One popular Kara female oc fanfiction might be the ones where the original character (oc) has a unique friendship with Kara. For example, there could be a story where the oc is a new alien on Earth and Kara helps her adapt, which often includes elements like exploring the new powers of the oc and their shared experiences of being different.
One common theme is friendship. The OC often becomes a close friend to Kara Danvers, and they go through various adventures together. Another theme is the OC having special powers or abilities and how they interact with Kara's powers. It can create some really interesting storylines.
The new perspectives. An OC (original character) can bring in fresh ideas and storylines. For instance, an OC could have a unique power that changes the dynamics in the Supergirl world.
Yes, there are many. You can start by looking on fanfiction websites like Archive of Our Own. Just search for 'kara supergirl oc' and you'll find a variety of stories. Some might focus on Kara's adventures with a new original character, while others could be more about the relationships that an OC forms within the Supergirl universe.
A common theme is power exploration. Since Kara and Superman have superpowers, an oc in these fanfictions might also have powers or be in the process of getting them. Another theme could be friendship. The oc might form a strong bond with Kara and Superman, like helping them through a tough time or vice versa.
Fanfiction.net is also a great place to look. It has a large collection of fanfictions for various fandoms, including Detroit: Become Human. However, the quality can vary, so you might need to skim through a few to find ones that really focus on the OC x Kara relationship in a way that you like.
Next, plan out the plot. It could start with the oc arriving in National City. Maybe she has a special power or ability that gets Kara's attention. You can also include some of the existing characters from the Kara universe in your story to make it more engaging. For instance, have the oc meet Alex or J'onn. As you write, keep in mind the tone of the Kara series, usually a mix of action, drama, and a bit of humor.