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.
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.
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.
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.
One common theme could be redemption. Kovu has a complex past and his relationship with Simba can be a vehicle for exploring how he can redeem himself in Simba's eyes or in the eyes of the pride.
One great Simba x Kovu fanfic could be 'The Unlikely Bond'. It delves into how their relationship might develop in an alternate universe where they have to team up against a common threat. In this fanfic, their initial distrust gradually turns into respect and then friendship as they realize they share the same goal of protecting the Pride Lands.
Typically, in 'Simba x Kovu' yaoi fanfic, there would be a strong focus on the relationship between Simba and Kovu. It might explore their emotional connection in a more romantic or sexual way that goes beyond the normal platonic or rivalrous relationship seen in the original Lion King story. There could be a lot of character development specifically centered around their feelings for each other.
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.