One plot idea could be that the OC is a ninja from another village who has a secret relationship with Kakashi. When she becomes pregnant, she has to decide whether to stay in her village or try to be with Kakashi in Konoha. This could create a lot of tension and drama, especially with the political implications between the two villages.
A more complex plot could be centered around any potential threats to Rin during her pregnancy. There could be enemies who see this as an opportunity to target them, so Kakashi has to be extra vigilant in protecting her. This could lead to some intense action scenes where Kakashi uses his Sharingan to fend off attackers while also ensuring Rin's safety.
One idea could be that the OC, now as Kakashi, has to deal with the same traumas Kakashi had but with a different perspective from their original self. For example, they might handle the loss of their comrades in a new way that changes the course of events in the Naruto world.
Maybe an OC from a different village who is sent on a mission with Kakashi. Their different backgrounds and skills create an interesting dynamic during the mission. For example, the OC could be a master of water jutsu and Kakashi has to adapt his combat style to work with them.
One idea could be that they face challenges in their ninja duties while being pregnant. For example, they have to deal with enemies who might target them because of their vulnerable state. Another could be the support they get from their friends and the village. Their friends could help them with things like getting proper medical care and protection.
One plot idea could be an OC who is pregnant and trying to hide it from powerful enemies in King's Landing. She has to navigate the dangerous political intrigue while protecting her unborn child.
One idea could be an OC who is pregnant and is trying to hide it from the warring factions in King's Landing. She might be a servant in the Red Keep and is afraid of what will happen if her pregnancy is discovered, as she doesn't know who the father is among the many lords and knights who frequent the castle.
One plot idea could be the challenges she faces in hiding her pregnancy from certain characters in the fanfic's world. Maybe there are those who would use it against her or the group she's associated with.
Maybe the OC is pregnant and it's a result of a forced situation in the Capitol. This could add a whole new layer of motivation for her in the Hunger Games. She could be fighting not just for her own survival, but also for the future of her unborn child. And she might form alliances with other tributes who are sympathetic to her situation.
One idea could be exploring Kakashi's relationships within the Anbu. For example, his friendships or rivalries with other members. Maybe there was a particular mission where he had to rely on a teammate he didn't trust at first.
One idea could be exploring how the pregnancy affects Daenerys' political decisions. Since she's in a powerful position, she might have to balance her new role as a mother - to - be with her leadership. Another could be the reactions of her allies and enemies. Her allies might see the unborn child as a symbol of hope and a continuation of her dynasty, while her enemies could plot to use the pregnancy against her.