I haven't actually come across a 'Dursleys kills Harry Potter' fanfiction. It's a rather disturbing concept considering how the story of Harry Potter is centered around his survival against Voldemort. The Dursleys are just part of his Muggle upbringing with their own brand of meanness. If there were such a fanfiction, it would probably change the whole trajectory of the story. For example, the wizarding world would lose its Boy Who Lived, and it would be interesting to see how the characters like Dumbledore or Hermione would react to such a tragic event.
In some interpretations, it could be that Harry finally snaps after years of abuse from the Dursleys. Maybe they pushed him too far one day and in a fit of rage, he uses his magic to end their lives. It's a very dark and extreme take on the Harry Potter universe.
There are likely 'Harry Potter Kills Dursleys' fanfictions. Fanfic writers often like to explore extreme scenarios. In this case, it could be a way to show how far Harry could be pushed. It might also be a commentary on the Dursleys' horrible treatment of Harry. But this goes against the somewhat forgiving nature of Harry in the original books.
It could start with a build - up of small incidents. For example, the Dursleys constantly belittling him even after he has proven himself in the wizarding world. Then, one major event, like the Dursleys trying to sell his magic items or preventing him from going back to Hogwarts, causes Harry to snap. His killing of the Dursleys could then lead to a search for redemption or a fight against those who want to punish him unjustly, as he was pushed to his limits by their cruelty.
Well, if we consider this in the context of fanfiction, it might be a very extreme exploration of the 'dark!Harry' trope. However, it goes against everything Harry represents in the original series. Firstly, the Dursleys, despite their mistreatment of Harry, are Muggles and killing and eating them is an inhumane act. This would cause a huge uproar in both the Muggle and wizarding worlds. Harry would be seen as a monster.
Some authors might create it as an exercise in 'what - if' scenarios. They want to break the established narrative and see how different characters would react if Harry was killed so early. Also, it could be a way to explore the Dursleys' characters more deeply, showing just how far their hatred for Harry could go.
The wizarding world's reaction would be complex. On one hand, Harry's friends like Hermione and Ron might be conflicted. They know the Dursleys were awful to Harry, but they also believe in the value of life. Wizards who have a strong sense of justice might understand Harry's actions, especially those who have also faced prejudice or abuse. But the more traditional and law - abiding members of the wizarding community would condemn Harry, and the Ministry would likely try to arrest him, leading to a possible conflict between those who support Harry and those who don't.
The original Harry Potter series promotes forgiveness and the power of love. Harry is shown to be a kind - hearted character who believes in the good in people. But in the 'harry kills the dursleys fanfiction', it goes against this. It shows a more vengeful and darker side of Harry that is not in line with his character in the books. It also changes the family dynamic aspect which is an important part of the original story.
In the 'the dursleys abuse harry fanfiction', the abuse can be multi - faceted. Physically, Harry could be pushed around or hit by Vernon. Emotionally, Petunia might constantly compare him unfavorably to Dudley, which is really damaging to Harry's self - esteem. And socially, they might prevent him from having any friends over, making him feel completely alone in the world.