I'm not entirely sure if there is a specific 'kovu and kiara pregnant fanfiction' out there. It depends on the creativity of the fanfic writers in the community. Some might find the idea of them having a family an interesting plot point and have written about it, while others may not have explored this aspect yet. You could also check some specialized Lion King fanfiction groups or forums to see if anyone knows of such a story.
The main characters are clearly Kiara and Kovu. Kiara, being pregnant, is at the center of the story. Kovu, as her mate, is also a very important character as he will be involved in all the events related to Kiara's pregnancy, like taking care of her and preparing for their cubs.
One possible plot could be about how Kiara and Kovu deal with the upcoming arrival of their cubs. They might face challenges like finding a safe place to raise their family in the pride lands. There could also be excitement among the other animals in the pride as they await the new arrivals.
Try Archive of Our Own. It has a large collection of fanfictions from various fandoms. Just use the search bar and type in 'kovu and kiara pregnant' and see what comes up.
Kiara and Kovu's love story is one of unity between two different worlds. They initially meet and there is an attraction. Despite the enmity between their prides, their love grows. Kovu was sent to get close to Kiara for a purpose, but he truly falls for her. Eventually, they overcome the differences and prejudices of their respective groups to be together.
The key elements include their different backgrounds. Kiara grows up in a peaceful Prideland, while Kovu has a more rugged upbringing among the Outsiders. Their personal growth also plays a role. As they get to know each other, they change. And the external pressure from their respective groups trying to keep them apart is a major element in their love story.
Since 'lemon' content is inappropriate, let's consider their general characteristics. Kovu is often depicted as a strong and determined character. He has to deal with his past and his place in the Pride Lands. Simba is the noble king, with a sense of responsibility. In proper fanfiction, their interactions might show Kovu learning from Simba's wisdom and Simba coming to accept Kovu as part of the pride.
Their friends might offer practical support like helping them with shopping for baby supplies. They could also provide emotional support, just being there to listen when JJ or Kiara are feeling stressed about the pregnancy.
Perhaps the fanfiction could focus on the community's reaction to their pregnancy. Their friends could be super supportive, throwing baby showers and helping them out. Or there could be some gossip in the community which they have to deal with. Like some people might spread rumors that they got pregnant on purpose for some ulterior motives, and they have to prove those people wrong.
Kiara herself is of course the most important. Her mate would also be very important as he would support her through the pregnancy. Simba, as her father, would likely play a significant role too.