It could be due to a lack of information. Artemis might not have known all the facts about Percy. For instance, if there was some sort of illusion or false information spread around, she could have misjudged the situation and accidentally killed him. Also, perhaps in the heat of a battle, she didn't have time to properly identify her target and made a tragic mistake.
In some fanfiction concepts, it could be related to a prophecy. Maybe there was a prophecy that was misinterpreted. Artemis, thinking she was fulfilling her role according to the prophecy, ended up killing Percy by accident. Or it could be that some dark magic influenced her actions, causing her to lose control and harm Percy without meaning to.
The story could also deal with the aftermath in a more emotional way. For example, Annabeth, who was close to Percy, might go into a deep depression. Artemis, realizing the full impact of what she has done, might then embark on a journey to atone for her mistake. This could involve helping those Percy cared about, or trying to restore the balance that Percy's death has disrupted in the mortal and godly worlds.
One consequence could be the anger of the other gods. Artemis is a maiden goddess, and her marriage to Percy would go against her long - held vow. Gods like Apollo might be very unhappy and could cause all sorts of problems for Percy. Another consequence is the impact on the demigod world. Percy has his own friends and allies, and this unexpected marriage could change his relationships and status among them.
One possible reason could be a misinterpretation of a prophecy. Maybe Artemis believes Percy is a threat to the natural order she protects based on a wrongly interpreted prophecy. For example, if a prophecy was worded ambiguously and she thought Percy would bring destruction to the wild, she might take drastic action.
One possible reason could be a misunderstanding. Maybe Percy accidentally disrupted one of Artemis's hunts or sacred rituals in the fanfic. Another reason might be that some prophecy or fate in the fanfic's made - up world has pitted them against each other. For example, if there's a prophecy that Percy's actions will somehow limit Artemis's power or freedom in the future.
Well, perhaps in this fanfiction, Artemis betrays Percy for Orion due to a prophecy. There could be a prophecy that states that Orion and Artemis together will bring about some great change or prevent a huge disaster, and Artemis believes she has to choose Orion over Percy to fulfill it. Also, Orion might have some sort of leverage over Artemis that forces her to turn her back on Percy.
One possible reason could be a misunderstanding. Maybe there was some miscommunication or false information spread that made Artemis think Percy had done something unforgivable. For example, if Percy was wrongly accused of harming one of Artemis' beloved creatures or desecrating her sacred places.
One possible storyline could be that there is a misunderstanding. Maybe Artemis is under some kind of dark magic influence that makes her think Percy is a threat to the natural order she protects. So she sets out to kill him, but as the story progresses, Percy tries to prove his innocence and find a way to break the spell on Artemis.
One possible reason could be differences in their divine natures. Percy is a son of Poseidon, a god associated with the sea and a more fluid, emotional element. Artemis is a virgin goddess of the hunt, very strict and unyielding in her ways. This contrast in their essences might lead to clashes and Percy's dislike.
Percy could lose trust in the gods completely. After Artemis' betrayal, he might feel that he can't rely on any of them anymore.
Perhaps it's a reaction to certain male - centered storylines in the original series. Writers might want to create a different narrative where the female characters are in control and their dislike for boys is a way to assert their own agency. Also, it could be a form of character development exploration, seeing how these characters' personalities change when they have this strong opinion towards boys.