It could be that the way the child is written in the fanfiction goes against Annabeth's character. For example, if the child is depicted as being overly needy or bratty and Annabeth, who values independence and order, just can't stand it. Also, it might be that the existence of the child changes Percy in a way that Annabeth doesn't like. Like Percy starts to neglect her in favor of the child.
Maybe in some fanfictions, the writers change the characters' personalities too much. Annabeth is a strong - willed character, and if Percy is portrayed in a way that goes against their original relationship dynamic, she might seem to 'hate' him in that fictional context.
It could be that the fanfiction plots are so convoluted. For example, the writer might create some really out - of - character situations for Percy and Annabeth. If Percy is constantly put in scenarios where he's made to be at odds with Annabeth in ways that don't feel true to the original series, it could give the impression that he hates her in the fanfiction.
Perhaps Annabeth's dad has some old - fashioned ideas. He might believe that Percy doesn't have the right qualities to be with his daughter. He could also be jealous in a way. Percy is an important person in Annabeth's life and her dad might feel left out or that Percy is taking his place in a sense.
Maybe they have a different taste in literature. They might prefer other types of stories and not be into the fanfiction genre, especially those related to Percy and Annabeth.
It could be that Percy's arrival disrupts the balance or routine at camp, which Annabeth doesn't like. Or perhaps there's some jealousy or competition involved.
It could be that Annabeth has a misunderstanding about Percy. She might think he's a threat to her position or status at the camp, so she bullies him to try and keep him in check.
In fanfiction, Percy could hate the gods due to their lack of proper care for their demigod children. They are often absent and don't really step in to help when the demigods are facing real hardships. For example, Percy has been through numerous life - threatening quests where the gods could have made things easier but didn't. This builds up resentment towards them.
In fanfiction, there could be a whole bunch of reasons. Artemis is the goddess of the hunt, virginity and the moon. Percy is a son of Poseidon. Their powers and natures are quite different. Perhaps in some stories, Percy's actions, like his impulsive behavior or his way of handling situations, clash with Artemis' more reserved and calculated approach. This could lead to her hating him.
In the fanfiction, perhaps there are misunderstandings between Percy and Calypso. Maybe she blames Percy for things he didn't do or vice versa. These constant misunderstandings can lead to Percy hating her.
Maybe Percy just doesn't like the whole idea of combining poker with fictional stories. It could be that he finds the concept of writing fanfiction about poker really unappealing. For example, he might think that poker is a serious card game and doesn't fit well with the often creative and sometimes out - there nature of fanfiction.