Well, in a Thirteenth Doctor OC fanfic, it's important to capture the essence of the Thirteenth Doctor's character. She's energetic, curious, and always ready for an adventure. Your OC could be someone who gets caught up in one of her adventures by accident. For example, they could be a scientist working on a project that the Doctor is also interested in. This could lead to a great story of discovery and teamwork.
In a Thirteenth Doctor OC fanfic, pacing is crucial. You don't want to rush the relationship between your OC and the Doctor. Start with small encounters, like the OC seeing the TARDIS for the first time and being curious. Then, as the story progresses, build up to more significant events, such as them traveling together through time and space. Also, pay attention to the dialogue. It should feel natural and reflect the personalities of both characters.
Another interesting idea is a time - travel based fanfic. The Thirteenth Doctor could accidentally go back in time to a point in Earth's history where she has to solve a mystery that is somehow connected to a future threat she has faced. This would involve her using her wits and knowledge of both past and future to save the day.
Yasmin Khan would be a great character to include. She was one of the Doctor's companions and her relationship with the Thirteenth Doctor was full of friendship and adventure. Her skills and her growth throughout her time with the Doctor can add depth to the fanfic.
In the fanfiction, their meeting is often full of surprises and unexpected plot twists. It might involve time travel paradoxes or joint efforts to save the universe.
One interesting thirteenth doctor fanfiction could be about her adventures in an alternate universe. In this story, she might encounter versions of her old companions in very different circumstances.
One common theme is the eternal struggle between good and evil. The Thirteenth Doctor represents good, while the Master is often the face of evil. Their interactions are full of this push - and - pull dynamic.
Archive of Our Own (AO3) is also a great place. It has a well - organized tagging system, so you can easily find thirteenth doctor fanfiction. There are different genres and ratings to choose from depending on your preference.