It could be that Annabeth leaves Percy with the child because she has some family issues to deal with in her mortal family. She entrusts Percy with the child because she knows he's strong and capable. Percy is initially clueless about how to take care of a child but slowly learns. He might start by teaching the child about their demigod powers in a fun and safe way. The fanfiction could show how their relationship develops as Percy becomes more of a father figure, and how he waits for Annabeth's return, hoping that they can be a family again.
Perhaps Annabeth is forced to leave because of a prophecy. She believes that by leaving Percy with the child, she is protecting them both in some way. Percy then has to struggle with his own feelings of abandonment while also trying to raise the child. He might seek help from his friends at Camp Half - Blood, like Grover. Grover could help him understand the child's needs better as he has some experience with young creatures. The story could then follow Percy's journey of self - discovery as he becomes a more responsible and loving father.
Well, perhaps it could start with Percy feeling unfulfilled in his relationship with Annabeth. He might meet Calypso and be enchanted by her. Calypso could offer him a different kind of life, away from the battles and stress with Annabeth. Maybe Percy starts to see Annabeth more as a comrade than a lover at this point and decides to leave her for Calypso.
Percy would probably feel a mix of shock and confusion at first. He might wonder why Annabeth left him with this huge responsibility. Then he would start to feel a bit scared because he doesn't know if he can take care of the child properly.
Well, perhaps in the fanfiction, Annabeth could initially be in denial about being pregnant after Percy leaves. But as time goes on, she starts to accept it and decides to focus on building a better future for her and the baby. She might also get support from her friends like Grover, who could help her out in various ways, such as finding a safe place to stay and providing emotional support.
One reason could be that she's scared. The idea of becoming a mother at that point in her life might be overwhelming, and she might think she can't handle it with Percy. Maybe she wants to protect Percy from the difficulties that come with the pregnancy as well.
Perhaps there are external factors at play. The world of demigods is full of chaos and danger. Reyna might be in a position where Percy feels he has to be by her side to protect her or to fulfill some greater prophecy that involves the two of them, and this leads to him leaving Annabeth.
Well, in some fanfiction, it could be due to a misunderstanding. Maybe Percy did something that Annabeth misinterpreted as a betrayal, like not being honest about a new power he discovered. This lack of trust then led to their break - up.
One possible reason could be a misunderstanding. Maybe there was a miscommunication between Annabeth and Percy about their future plans or how to raise their child. Another reason might be some external threat that Annabeth believes she can face alone to protect her family, so she leaves them behind. It could also be that she has some personal issues to deal with, like an identity crisis, which makes her think she's not fit to be with them for the time being.
He could go on a desperate search for her. Percy is a very determined person. He would try to find out the reason for her leaving. He might ask all their mutual friends and look for clues everywhere. Meanwhile, he would also be trying his best to take care of their child. He would be heartbroken but also focused on keeping their family together in some way.
It could also be a matter of self - discovery. Annabeth might have been on a journey to find out who she was outside of her relationship with Percy. Meeting this mortal was a turning point where she realized she wanted to explore a different path, even if it meant leaving Percy. Maybe she thought that being with a mortal would give her a chance to have a more ordinary life, at least for a while.
Well, Percy could have a range of reactions. At first, he might be in denial, not believing that Annabeth would actually leave him for a job. Then, as it sinks in, he could get angry. He's a passionate guy, and this would be a big blow to him. He might also feel a bit of envy towards the job that seems to have taken Annabeth away from him. In the long run, though, he could use this as a chance to grow on his own and become more independent.