One possible plot could be that Thalia has to deal with the shock of the unexpected pregnancy. She might struggle with how it will affect her life as a demigod. For example, she may worry about how she can continue her duties while being pregnant. Maybe she'll also face judgment from some of her peers in the demigod community. She could then start to think about the future of the baby and whether it will inherit her powers or face the same dangerous world she has.
There's also a chance that it could be a god in disguise. Gods have been known to have relationships with mortals and demigods. So perhaps a god took on a human form and had a relationship with Thalia, resulting in the pregnancy.
Her character could develop by becoming more responsible. Since she's pregnant, she has to think about another life. So she might start making more careful decisions, like not rushing into dangerous situations without a plan.
In a 'pregnant' fanfiction, their relationship would become more complex. There would be new layers of love and responsibility. They would start to see each other in a different light, not just as friends or fellow demigods. Percy might see Thalia as the mother of his child, and Thalia would see Percy as the father. This new perspective would bring out different aspects of their personalities. For example, Percy might show a more nurturing side, and Thalia might become more patient. Their relationship would be tested by the challenges of pregnancy, but also strengthened as they face them together.
One idea could be exploring how their demigod powers are affected during the pregnancy. For example, Percy's control over water might become more erratic due to hormonal changes. Another could be the reactions of their friends and the demigod community. Some might be supportive, while others might fear for the future of the half - bloods. Also, they could face challenges from the gods, as the birth of a new demigod with such powerful parents could shift the power balance in the mythological world.
One plot idea could be Thalia having to deal with the challenges of being pregnant while still being involved in her heroic duties. Maybe she has to hide her pregnancy from some of her enemies. Another could be exploring how her friends in the story react to the news and support her through it.
This is a very unorthodox and non - canon idea. However, if such a fanfic were to exist, perhaps the plot could involve Percy and Thalia having to deal with the shock and the sudden change in their lives. They might face judgment from their friends and the demigod community. But this goes against the established relationships in the original works.
A popular one is 'Thalia and Percy: The New Prophecy'. It takes place after the main series and imagines a new prophecy that involves both of them. The story has a lot of action and adventure, and the way the author writes their interactions is really engaging.
I really like 'Thalia and Percy's New Quest'. In this fanfic, they are sent on a special mission that no one else could handle. The author does a great job of portraying their individual strengths and how they combine them to succeed. It's full of action and a bit of humor too.
One great 'Percy Jackson Thalia Grace' fanfiction is 'The Lost Sibling'. It delves into a scenario where Thalia and Percy discover they are long - lost siblings. The author does an amazing job of portraying their initial shock and then the gradual building of a strong bond. It has some really exciting battle scenes against mythical creatures too.