One popular fanfic could be 'The Ultimate Sacrifice'. In it, Harry's self - sacrifice is a very emotional and heroic act. He does it out of deep love and friendship for Hermione.
In the fanfic, it could be that Fleur is in a situation where she has to perform a dangerous task to save the wizarding world, like going into an ancient and deadly magical place. Harry, realizing the importance of her mission and also having deep feelings for her (maybe a secret love), sacrifices his own safety by going with her and ultimately giving his life to ensure she can complete the task and save everyone.
In many fanfics, it's related to a powerful dark magic threat. Harry might sacrifice himself to protect Hermione from a dark spell or a powerful enemy. For example, he could jump in front of a killing curse meant for Hermione. His sacrifice is usually seen as an ultimate act of love and friendship, and it often has a big impact on the wizarding world in the fanfic. It might inspire others to be more selfless or it could change the balance of power between good and evil.
The Weasleys would be devastated. Bill, Fleur's husband, would feel a mix of gratitude towards Harry and intense guilt for not being able to save Fleur himself. Ginny would be heartbroken, having once had feelings for Harry. Hermione would be in shock and would probably spend a lot of time trying to figure out if there was any way they could have prevented it. Ron would be angry at first, angry at the situation and at the bad guys who put Fleur in danger, but also deeply sad for losing his friend.
Well, it could be that Naruto sacrifices himself to seal away a dark and ancient curse that is threatening to destroy not only the ninja world but all of existence. He realizes that his unique connection to the tailed beasts and his strong willpower make him the only one who can perform this self - sacrificing sealing jutsu. So, he says his goodbyes to his friends, family, and the village he loves and gives up his life to save everyone.
In some fanfictions, if Harry Potter sacrifices himself, it could lead to a dark and desolate wizarding world. His friends would be left to pick up the pieces, mourning his loss deeply. For example, Hermione might be driven to find a way to reverse his sacrifice through her vast knowledge, while Ron would be filled with a sense of vengeance towards the forces that led to Harry's death.
It could be a long - lost Uchiha with powers beyond that of Madara. This Uchiha could have been in hiding, gathering power and knowledge, and his ultimate goal is to reshape the world in his own dark image. Naruto realizes that the only way to stop him is by sacrificing himself.
I'm sorry I can't directly recommend a specific 'Percy sacrifices himself for Artemis' fanfic. But you can try searching on fanfic platforms like Archive of Our Own (AO3). There are tons of fanfics there, and by using relevant keywords in the search bar, you might be able to find one that suits your interest.
One key plot point could be the revelation that Snape is in some sort of danger that only Harry's sacrifice can prevent. Maybe it's a curse placed on Snape by Voldemort that can only be broken if Harry gives his life. Another point could be Harry's decision - making process. He would have to grapple with leaving his loved ones behind. And finally, the moment of sacrifice itself, which could be a very emotional and magical scene.
The immediate impact would likely be chaos. Criminals would feel emboldened, thinking that there's no one to stop them. The police force would be under a great deal of stress as they try to fill the void left by Batman. However, Batman's sacrifice could also inspire new heroes to rise up. People who were inspired by his selfless act might take it upon themselves to protect the city in their own ways.