One idea could be that they face challenges in their relationship due to the unexpected pregnancy. For example, Oliver might worry about how his vigilante life could affect the baby and Chloe. Another could be that they go on a journey to find a safe place for their family, away from the threats in Smallville. They could also have to deal with the reactions of their friends and family, some of whom might not be as supportive as they hoped.
A plot could revolve around Chloe using her journalistic skills to uncover a mystery related to her pregnancy. Maybe there are some strange medical phenomena that she wants to understand. Oliver, on the other hand, tries to protect her from any potential danger while also preparing for fatherhood. They could also have flashbacks to their earlier relationship moments and how they got to this point in their lives.
Perhaps they discover that the pregnancy has some sort of super - power implications. Since Smallville is full of strange things, it could be that the baby has some special abilities that start to show even before it's born. This could lead to them having to find a way to protect the baby from those who might want to use its powers for evil. They also have to balance their normal lives with these new and unexpected developments.
Well, perhaps Oliver has been poisoned in a way that affects his mental state. This poison could make him paranoid and see Chloe as an enemy when she's really not. Or, in a more complex plot, Oliver is trying to protect Chloe from a greater danger but his methods are misinterpreted and end up hurting her. For example, he might be trying to keep her away from a powerful enemy by pushing her away harshly.
One possible plot could be that they face challenges from their families. Maybe Oliver's family has certain expectations for him and the baby, and Chloe's family is worried about her future. Another aspect could be how they balance their superhero/vigilante activities with preparing for the baby.
Maybe a story where they discover the pregnancy in an unexpected way. Like, they were on a mission together and Chloe starts feeling unwell. After some tests, they find out she's pregnant. Then it could be about how they break the news to their friends and family in Smallville. Lois might be overly excited and Clark could offer his support in a very Clark - like, selfless way.
The plot could be that Chloe and Oliver have a secret relationship in Smallville. One day, Chloe realizes she's pregnant. They then have to decide whether to keep it a secret or tell their friends. Their friends in Smallville, like Clark, might have different reactions. Some could be supportive, while others might be skeptical about their relationship and the pregnancy. As the pregnancy progresses, Oliver and Chloe face challenges such as dealing with Chloe's health issues during pregnancy and preparing for the baby's arrival.
One idea could be that Chloe discovers a hidden power in Smallville that is linked to her own family's past. Maybe she stumbles upon an old diary in the Kent barn that reveals secrets about a long - forgotten relative who had a connection to an otherworldly force in Smallville. This could lead to her and Clark teaming up to uncover more about this mystery and protect Smallville from a new threat that is drawn to this newly - discovered power.
There could be a fanfic where Chloe gets pregnant by accident with Oliver in Smallville. At first, they are both shocked and a bit scared. But as time goes on, they start to see it as a new beginning. Oliver might have to face his own fears about being a father, while Chloe could be worried about how her pregnancy will affect her work or her friendships in Smallville. Eventually, they grow closer as they anticipate the arrival of their baby.
I'm not sure of specific fanfics on this topic. But you can try searching on fanfiction - dedicated websites like Archive of Our Own or FanFiction.net. Just type in 'Smallville Chloe pregnant with Oliver' in their search bars, and you might find some great reads.
Clark might be initially shocked but then very supportive. He would probably offer his help in any way he could, given his own experiences with dealing with extraordinary situations. Lois might be a bit more outspoken, giving Chloe advice on motherhood and also teasing Oliver about becoming a dad. Tess could see it as an opportunity to use their situation to her advantage in some way, but eventually come around to being supportive.
Definitely Clark. He has always been a central figure in Smallville. His friendship with Chloe and his acquaintance with Oliver make him a natural addition. He could offer his super - strength to help protect Chloe during her pregnancy if needed, and also give Oliver some advice on being a good partner and father based on his own values.
Maybe the pregnancy is unexpected, and they initially panic. But then they start to get excited about building a family together. Chloe could start to train Lucifer on how to be a good father, like teaching him about baby care and normal family values, which would be a big change for him since he's from Hell.