The old enemies of Percy and Annabeth like the Titans or some of the more vengeful monsters could be the main antagonists. They might see the unborn child as a threat or an opportunity to get back at Percy and Annabeth.
It could be that some of the gods who are not happy with the idea of demigod - demigod relationships or the potential power of their unborn child become the antagonists. These gods might try to disrupt the pregnancy or cause problems between Percy and Annabeth in order to prevent the birth of the child that they see as a future rival or a disruption to the order they want to maintain.
It could be an old enemy from Greek mythology that has been resurrected. For example, a powerful Titan who has a vendetta against the demigods, especially Percy and Annabeth.
Often, it could be old enemies like the Titans. In fanfiction, they might return in new and more devious ways. For example, Kronos could have a new plan to break Percy and Annabeth apart before trying to take over the world again.
Often, it could be a jealous classmate. Maybe someone who has a crush on Percy and sees Annabeth as a threat, so they try to create problems between them. Another could be a strict teacher who doesn't like Percy's carefree attitude and Annabeth's independent thinking, always trying to give them a hard time.
In some fanfictions, it could be an ancient and powerful Titan that has been resurrected. This Titan might be seeking revenge on the demigods, especially Percy and Annabeth, because of their past victories over the Titans. Their powers and knowledge from the old times would pose a great threat to our heroes.
Some rogue demigods who are power - hungry could also be the antagonists. They might see the baby as a way to gain more power, like if there are rumors that the child will have special abilities. So they would try to either steal the baby or harm Annabeth to prevent the birth.
There might be some new characters introduced in the fanfiction who have different ideals or motives that clash with Annabeth's. These new characters could be the antagonists as they oppose Annabeth, and Percy has to step in. For example, if they think Annabeth's way of handling a certain quest is wrong and Percy believes in her, he'll fight against their ideas.
The main antagonists could be some of the other gods who are jealous of Aphrodite's special situation with Percy. For example, Hera might not like the idea of Aphrodite having a child with a demigod, as it goes against the normal order of things in the godly realm.
There are many fanfiction communities that might have such stories. Some authors like to explore the idea of Percy and Annabeth's future together in a more domestic setting. However, the quality can vary greatly. It's important to read reviews or summaries before diving into a particular story to make sure it's something you'll enjoy. You could also join fan groups dedicated to Percy Jackson and ask for recommendations there.
Finding a fanfiction with the exact title 'Percy and Annabeth Lemon Pregnant' can be a bit of a challenge. It depends on how popular the idea is among the fanfiction writing community. Some fanfiction writers might shy away from such a plot because it could be seen as a bit out - of - the - ordinary or not in line with the general tone of the original series. But it's always worth looking on different fanfiction platforms and seeing what you can find.
The gods could potentially be antagonists. If the pregnancy goes against some divine law or prophecy, they might try to interfere. For instance, Zeus could see it as a threat to the order of things and send his minions to cause trouble for Percy and Bianca.