I haven't come across a 'pikachu kills ash fanfiction' myself. But in the world of fanfiction, people sometimes create very extreme and unexpected scenarios. If such a fanfiction exists, it may be written by someone who wants to explore the darker side of the Pokémon universe or perhaps is trying to make a statement about the relationship between Pikachu and Ash. It might shock and intrigue readers who are used to the positive and heroic portrayals of the characters in the official Pokémon media.
I'm not sure if there are extremely popular ones specifically with this plot. However, in the vast world of fanfiction, there might be some that have gained a bit of a following among a niche group of Pokémon fans who are interested in darker and more alternative storylines.
It's doubtful that it's a popular fanfic. Popular fanfics usually tend to build on the positive aspects of the source material, like the friendship or adventure between characters. A concept where Ash kills Misty is so out of the ordinary and negative that it probably doesn't appeal to a wide audience. However, there might be a small niche of readers who are interested in very dark and alternative fanfics, but overall it's not likely to be popular.
I'm not sure specifically what this 'ash kills misty fanfic' is about as there could be many different interpretations. It might be a very specific and perhaps dark or alternative take on the relationship between Ash and Misty in a fan - created story.
Well, a 'May kills Ash' fanfiction might involve a plot twist where May has been brainwashed by a villain. She could be made to believe that Ash is a threat to the world they live in, and so she takes it upon herself to eliminate him. This could lead to a very intense and emotional story as their friends try to figure out what happened and stop May.
One possible motive could be that Mewtwo sees Ash as a threat to its own power or freedom. Ash is constantly on a journey to catch and train Pokémon, and Mewtwo, being a powerful and intelligent Pokémon, might view Ash's actions as a potential danger to its kind or its own existence.
One possible motive could be that Team Rocket has constantly been causing trouble for Ash and his friends. They've been trying to steal his Pokémon time and time again, which might have finally pushed Ash over the edge.
Maybe the creator wants to explore a different side of Pikachu's character. In the official story, Pikachu is loyal and friendly, but in this fanfiction, it could be a way to show a corrupted or influenced Pikachu. Also, it could be a way to deconstruct the typical hero - sidekick dynamic between Ash and Pikachu and make readers think about their relationship in a new way.
The normal Pokémon storyline is about friendship, growth, and adventure. But in this fanfiction, it takes a dark turn with Mewtwo killing Ash. It completely changes the dynamic between humans and Pokémon. In the regular story, humans like Ash are seen as Pokémon trainers and friends, but here it shows a more violent and unexpected side of the Pokémon - human relationship.
I recommend the two novels, Naruto Noshi Village's Counterattack and Muye's Murder of Blood, to you. The main character of Naruto no Shimura Danzou's Counterattack was Shimura Danzou. He was from Kiba, but in the story, he betrayed Kiba and possessed great strength. Zhang Dingyu, the main character of "Muye's Murder of Blood", was also Muye's. However, he accidentally transmigrated to the Naruto World and was dissatisfied with the current system. He became someone who walked his own path. He could be considered to have betrayed Muye and was very powerful. These two novels were completed. I hope you like my recommendation. Muah ~