It could also be another demigod. Maybe someone she met during a new adventure or quest. This would add an interesting twist to the story as they'd have to figure out their relationship while also dealing with the pregnancy.
It could also be a new character introduced in the fanfiction. Maybe a powerful demigod from another camp who Annabeth meets during a diplomatic mission. This would create a whole new set of drama and conflict, as Annabeth would have to deal with her feelings for Percy and this new person, as well as the implications of having a child with someone other than Percy.
Another possibility is that it could be a god in disguise. Given the complex relationships between demigods and gods in the Percy Jackson universe, a god could have fallen in love with Annabeth and fathered her child. This would bring all sorts of divine drama and complications to the fanfic.
It might be an old enemy who somehow managed to get her in this situation as part of a devious plan. This would add a lot of drama and conflict to the story.
It could also be someone new, a character created specifically for the fanfiction. Maybe a powerful new demigod who catches Annabeth's eye, and their relationship leads to the pregnancy.
It could be his long - time partner. They might have had a very loving relationship that led to this situation.
Perhaps it's a mysterious stranger she met at a party. They shared a brief moment together, and now she's pregnant. Or it could be an old acquaintance who has always had feelings for her and took advantage of a vulnerable moment.
Maybe it's a new character introduced specifically for the fanfiction. This new character could be from a different faction or group, and their relationship with Makima could be full of intrigue and mystery. The pregnancy could be a result of some sort of strategic alliance or a passionate encounter between them.
It could be one of her close friends in the story. Maybe someone she has had a long - standing relationship with and the pregnancy was an unexpected but not entirely unwelcome result of their relationship.
Another option could be a mysterious figure. For example, a character from another dimension or a new character introduced specifically for this plot twist. This could add an element of mystery and intrigue to the story.
It could be a long - time love interest like Stefan. Their relationship has had its ups and downs, and a pregnancy could add a whole new layer of complexity to their story.