It could be some rogue ninjas who see Temari's pregnancy as a vulnerability and try to target her or Shikamaru. They might think that a pregnant Temari would be an easy target and that Shikamaru would be distracted, so they could try to carry out some evil plan against them.
There could also be a mysterious organization that is interested in the potential power of their unborn child. This organization could send spies or assassins to either kidnap Temari or manipulate the situation to their own advantage, seeing the unborn child as a valuable asset for their unknown and probably evil purposes.
One idea could be that they discover the pregnancy and start preparing their home for the new arrival. Shikamaru might be initially worried about how fatherhood will change his laid - back lifestyle but then realizes how much he wants to be there for his family. Temari could be dealing with her own concerns about motherhood while also being excited.
Their relationship would likely become more intimate. They would have to rely on each other more, sharing fears and hopes for the future with the baby. Shikamaru might become more protective of Temari.
Another plot could be that they keep the pregnancy a secret at first. Shikamaru is worried about how the village will react as he is an important ninja. Temari wants to wait until she is further along. But as time passes, they realize they can't keep it a secret forever and start to tell their closest friends and family.
One possible plot could be that they go on a mission together. Shikamaru's strategic mind and Temari's powerful wind jutsu would make them a great team. They might face a powerful enemy that requires both their skills to defeat. Along the way, they start to understand each other more deeply and their relationship begins to develop into something more than just comrades.
Elena could be an antagonist. Since she has a history with Christian, she might try to interfere with Anastasia's pregnancy, perhaps out of jealousy or a desire to maintain some control over Christian.
Another possible antagonist could be Zelena. Jealous of Belle's happiness and the new life she's bringing into the world, Zelena could try to cause trouble. She might use her magic to create false scares or difficulties during the pregnancy, like making Belle believe there are problems with the baby when there really aren't.
The main antagonists could be the same organizations they have always fought against. For example, Umbrella Corporation or any other bio - terrorist groups. These groups might see Ada's pregnancy as a weakness and try to use it against them. They could target Ada to get to Leon or try to harm the unborn child to stop Leon from interfering with their evil plans.
It could be Gabriella's over - protective father. He might think that Troy isn't ready to be a father and tries to convince Gabriella to break up with him. He believes that their pregnancy will ruin Gabriella's future and he's very strict about it, causing a lot of tension between the couple and him.
One possible antagonist could be Blair. If she still has feelings for Nate, she might see Serena's pregnancy as a threat to her relationship with Nate, whether it's a real relationship or just her own feelings. So she could try to create problems between Nate and Serena during the pregnancy.
One plot idea could be the couple preparing for the arrival of their baby. Shikamaru might be thinking of ways to balance his ninja duties with being a father, while Temari could be dealing with the physical and emotional changes of pregnancy. Maybe they face some challenges like the village not being fully supportive at first, but they overcome it together.