How would Percy and Annabeth's relationship change if they were lost siblings in fanfiction?

Their relationship would likely become more nurturing. They would have to rely on each other more as they take on the role of parents. For example, when the child has a nightmare about monsters, Percy might be the one to comfort the child first while Annabeth figures out how to better protect the home. Then they would discuss their concerns and fears for the child together, strengthening their bond as they face these new challenges as a couple.

Well, they would probably communicate better. In Tartarus, they had to rely on clear communication to survive. So, back in the normal world, this would carry over. They'd be more open about their feelings, fears, and plans, which would strengthen their relationship in a more emotional way.

They might become more protective. Since they are dreaming of having a daughter, they would start to think about all the potential dangers she could face. Their relationship could grow deeper as they bond over their shared hopes and fears for their future child.

The relationship will likely grow stronger. They'll have to rely on each other more for daily tasks and support. For example, if Percy has a bad day at work or school, Annabeth will be there to comfort him right away, and vice versa. However, it could also be a bit strained at times. There might be moments when they feel suffocated by each other's presence, but they'll have to work through those feelings to keep their relationship healthy.

Their relationship could become more intense. With her hearing his thoughts, they'd be more in tune with each other's feelings. It might make their bond stronger as they'd understand each other on a deeper level.

Their relationship would likely become even deeper. They would be partners not only in their heroic adventures but also in parenting. They would have to support each other in raising their child, like Annabeth helping Percy understand their child's academic needs while Percy might be better at teaching combat skills. They would also have to make decisions together about their child's future, whether it's about staying at Camp Half - Blood or trying to live a more normal life in the mortal world.

It could become more professional. They might keep their personal feelings aside and just focus on getting the job done.

Their relationship could become more complex. In highschool, there would be more social pressures. They might have to deal with classmates who are interested in one of them romantically, which could cause some jealousy. But it could also strengthen their bond as they face these new challenges together.

If Percy was the son of Achilles, his relationship with Annabeth might become more strained. Percy could become more headstrong and impulsive because of the influence of Achilles' traits, which would clash with Annabeth's more strategic and cautious nature. For example, in battle situations, Percy might rush in without a proper plan, causing Annabeth to worry more about his safety and get frustrated with his new behavior.

There might be some stress on their relationship too. The fear of the unknown, the potential danger to Annabeth during pregnancy in their dangerous world, and the responsibility of raising a child could all cause arguments or moments of doubt. But through it all, their love for each other and their growing family would likely keep them together and help them work through these difficulties.