They could face difficulties with their respective families. Ziva's family might have strong opinions about the pregnancy, and Gibbs' family (if we consider his past family life) could also be a factor. They would need to navigate through these family issues while also dealing with their own feelings about becoming parents.
One possible plot could be that Gibbs and Ziva are in a secret relationship. When Ziva discovers she's pregnant, she's initially terrified. Gibbs, on the other hand, is surprisingly calm and determined to support her. They face many challenges, like hiding the pregnancy from their colleagues at first. Gibbs starts to make small changes in their work environment to ensure Ziva's safety and comfort.
In this fanfiction, perhaps there could be a storyline where their pregnancy is a secret at first within the NCIS team. Gibbs and Ziva try to keep their normal routine while dealing with the physical and emotional changes that come with pregnancy. There could be some comical moments, like when Ziva has cravings during a case and Gibbs has to quickly find what she wants.
A plot idea could be that Ziva discovers she's pregnant during a dangerous mission. She has to keep it a secret not only from the bad guys but also from most of the team at first for fear of being taken off the case. Gibbs starts to notice her odd behavior and figures it out. They then have to work together to finish the mission while also protecting their unborn child.
It could be Tony. Their relationship has always had a certain chemistry, and it would make sense for him to be the father. It would add a new layer to their already complex dynamic.
In some NCIS fanfiction, Ziva could be pregnant. Fanfiction often explores different scenarios for beloved characters. Writers might create a story where Ziva's pregnancy brings new challenges and developments to her relationship with Tony. It could be a plot device to explore deeper emotions and create more complex storylines within the NCIS universe.
There's also 'Hidden Feelings'. In this fanfiction, the author delves deep into the unspoken attraction between Gibbs and Ziva. It has some really interesting plot twists that keep you engaged. The lemon aspect is tastefully done, adding a bit of spice to their relationship exploration.
One possibility could be that it would completely change their dynamic at work. They might become more protective of each other and start to think about their future outside of NCIS. For example, Tony might become more serious and start thinking about settling down in a more permanent way. Ziva, on the other hand, might struggle with how being pregnant would affect her role as an agent.
If they meet, there could be a lot of cultural clashes. Harry comes from a world where magic is normal and Gibbs is from a world where everything is based on scientific evidence and law enforcement. Harry might introduce Gibbs to things like butterbeer and thestrals. Gibbs could introduce Harry to things like NCIS procedures and how to handle a firearm. Their different perspectives could lead to some really interesting interactions and storylines.
The baby could become a central part of their team. The NCIS team would be like a big extended family, and everyone would have a role in the baby's life. For example, Ducky could be the baby's honorary grandfather, always ready with a story or some wisdom.
You can try fanfiction.net. It has a large collection of fanfictions including those related to Gibbs and Ziva. Just use the search bar and type in the relevant keywords to find the lemon fanfictions.