Daenerys is the main focus, of course. However, other important characters can include Varys. He might be involved in the intrigue surrounding her pregnancy, either helping to keep her pregnancy a secret if needed or using it to further his own political aims. Jorah Mormont could also be a key character. His loyalty to Daenerys would make him an important figure in protecting her during this vulnerable time. And there could be new characters introduced in the fanfic that are related to the events of her pregnancy, such as a healer who is crucial in ensuring the well - being of both Daenerys and the baby.
The main character is Daenerys. In addition, characters like Ser Barristan Selmy could play a role. He has always been a protector of the Targaryen name, and with Daenerys pregnant, his role in safeguarding her and the future heir would be even more significant. There may also be some of the Dothraki characters involved. Since Daenerys has a connection with the Dothraki, they might react in different ways to her pregnancy. Some might see it as a sign of her strength and the growth of their khalasar, while others might be more skeptical or try to use it to their advantage.
Obviously, Daenerys herself is the central character. But often, characters like Tyrion Lannister might be involved. He could be her advisor during her pregnancy, providing his sharp political insights. Jon Snow could also be a part of it, perhaps in a more complex relationship with Daenerys given their previous interactions in the original story. And of course, her loyal followers like Missandei and Grey Worm would likely be by her side, protecting her and the unborn child.