It could start with Artemis getting into a situation where she's in a vulnerable position. Maybe she's been lured into a place where her powers are diminished. Percy, being a friend and an ally, rushes to her aid. Along the way, he has to fight through hordes of lesser monsters, which takes a toll on him. When he finally reaches Artemis, they are confronted by a really powerful adversary. Percy realizes that the only way to save Artemis is to take the full brunt of the enemy's attack himself. So he does, and that's how he dies.
Percy's death would shatter the world of those who knew him. His friends like Tyson would be inconsolable. Tyson always saw Percy as a hero and a brother. The Hunters of Artemis might also be affected. They would respect Percy's sacrifice but also feel a sense of responsibility for his death. And the gods, who had often used Percy for their own ends, might start to question their actions. Some might feel remorse, while others might fear the chaos that could follow in the wake of Percy's death, as he was often a stabilising force in the often - tumultuous world of demigods and gods.
In this fanfiction, it could be that Artemis is in a situation where she is about to be killed or lose her powers forever. Percy, being the selfless hero he is, takes on a deadly task to prevent that from happening. Maybe it involves facing an ancient and malevolent god who has a vendetta against Artemis, and Percy uses his unique abilities and the element of surprise to try and stop this god, but at the cost of his own life.
Well, it would probably shatter Annabeth. Percy is her closest friend and love. His death would leave a huge void in her life. She might become more withdrawn, consumed by grief. She could also become more determined to carry on Percy's legacy in the fight against the forces they were up against.
It could be a powerful Titan who has escaped from Tartarus and blames Artemis for something in the past. So he's out to get her, and Percy has to stop him at all costs, even if it means his death.
Maybe he faced an extremely powerful enemy that he couldn't overcome. It could be a new and terrifying monster created by the Titans or some other dark force.
Perhaps it's due to the interference of the gods. The other deities might not approve of their relationship for various reasons. Maybe Zeus, fearing the power that could come from a union between Percy and Artemis, decides to put an end to it. In the world of Percy Jackson, the gods often meddle in the affairs of mortals and demigods, so this could be a factor.
On the other hand, she could try to honor Percy's sacrifice. Annabeth might focus on the reasons why Percy died for her and strive to fulfill any tasks or goals that he might have hoped she would achieve. She would carry on his legacy in a positive way, even though she is heartbroken.
The other characters would be devastated. Annabeth, for instance, would be heartbroken. She has been through so much with Percy, and his death would leave a huge void in her life. She might become more withdrawn and less trusting. Grover would also be deeply affected. He has been Percy's friend since the beginning, and he would probably blame himself for not being able to protect Percy. The other demigods would lose their hero, and they might feel less confident in their ability to defend Olympus.
Well, sometimes in fanfiction, his brother might be a mortal who discovers his demigod heritage later. This could add an interesting twist to the story as he has to adapt to the world of gods and monsters. Or it could be a long - lost half - brother from a different camp, like a son of Poseidon from another part of the world who was hidden away for some reason.
A possible plot twist in a 'Percy Dies Saving Artemis' fanfic could be that his death was not in vain, but rather a strategic move by some greater power. Maybe the Fates had planned it so that his death would create a distraction for an even greater evil that was about to be unleashed. Artemis, in her grief, could then discover this truth and be the one to take on this new threat with a new - found determination. Additionally, Percy's death could cause a shift in the balance of power among the demigods. With Percy gone, other demigods might step up in unexpected ways, and this could also play into the overall story as Artemis tries to navigate the new power dynamics in the demigod world.