Perhaps the fanfic could explore the relationship between Miss Martian and the father of the child. It could show how they support each other through the pregnancy, and also how their relationship evolves. There might be moments of joy, worry, and discovery as they prepare to become parents.
One possible plot could be that they face challenges in protecting their unborn child from enemies who might want to use the baby's powers for evil. Since both are Martians, their child would likely have unique and powerful abilities that could attract unwanted attention.
One common theme is the exploration of her relationships. For example, how her pregnancy might affect her relationship with her teammates or love interests. It could show a more vulnerable side of her character.
Obviously, Miss Martian herself is the central character. Her friends and teammates from the superhero group she belongs to could also be involved. For example, Superboy might play a role as a friend or protector. He could be there to support her during difficult times or help keep her and the baby safe from any threats.
One possible storyline could be about how Zuri deals with the changes in her body and her daily life. Maybe she has to adjust her work or study routine.
One possible storyline could be about Tenten's journey through pregnancy, facing the physical and emotional changes. For example, she might struggle with morning sickness at first and then gradually come to terms with the new life growing inside her. Another could be how her friends and comrades support her during this time, like Naruto and Sakura bringing her special foods to help with her cravings.
You can try looking on fanfiction platforms like Archive of Our Own (AO3). There are often a wide variety of fanfictions related to different characters and scenarios, including ones about Miss Martian being pregnant. Just use the search function on the site and type in relevant keywords.
Friendship and teamwork are also common themes. Since they are from different universes, they have to work together. They learn to trust each other and overcome their differences. In many fanfics, they form a strong bond that helps them face various challenges, whether it's a powerful villain or a difficult situation in a strange new world.
One plot idea could be that Naruto is somehow transported to the DC universe where he meets Miss Martian. They team up to fight a common enemy, like an alien threat that is causing chaos in both their worlds. Naruto could use his ninja skills and Miss Martian her telepathy and shape - shifting abilities.
Another storyline could revolve around the reactions of her fans in the fanfic. Some fans might be overjoyed and supportive, while others could be jealous or have mixed feelings. It could show how her pregnancy impacts the relationship between her and her fans on a fictional level.
One possible storyline could be how Iris manages her pregnancy while also dealing with the Flash's superhero duties. Maybe she has to be extra cautious and the Flash has to balance protecting the city and being there for her.