There are fanfictions where the Dursleys are nice, often by giving them more backstory or different motivations. It could be that they are nice out of fear of the wizarding world's retaliation if they mistreat Harry. Or perhaps they start to see Harry's value over time. In these fanfictions, Dudley might become friends with Harry, which is a far cry from their relationship in the original books. This new dynamic can add a whole new layer to the Harry Potter universe in the fanfiction world.
Fanfiction allows for creative interpretations of characters like the Dursleys. A nice Dursleys scenario might involve Petunia having a change of heart due to some magic - related event that makes her realize she's been wrong all along. This could lead to a more harmonious household for Harry. He might even get proper support and love from them. These types of fanfictions often explore the 'what - if' scenarios that many readers are curious about regarding the Dursleys' behavior.
In some Harry Potter fanfictions, the Dursleys are depicted as nice. This could be a really interesting take. It might show how they could have been different if they hadn't been so influenced by their dislike for magic. Maybe they could have supported Harry more, or at least been less cruel. For example, a fanfiction could explore a scenario where Vernon Dursleys actually encourages Harry's academic achievements at school, instead of always putting him down.
One way the Dursleys can be good in fanfiction is if they are forced to face the consequences of their actions early on. For instance, they might receive a warning from the wizarding world that if they don't treat Harry well, there will be serious repercussions. So they start to be nicer to him. They could provide him with a proper room, better food, and allow him to have friends over.
It might show the constant power struggle between them. Harry, as a wizard, has an inner strength that the Dursleys try to suppress with their mundane and cruel ways. So it's a battle of wills.
A lot of fanfictions play around with the Dursleys' relationship with Harry. They could be depicted as having a sort of begrudging respect for Harry. For instance, when Harry starts to show real courage and power, the Dursleys might start to see him in a new light. This is different from the original story where they mostly just try to suppress Harry. Also, some fanfictions might give the Dursleys magical abilities of their own, which completely changes their dynamic with Harry and the wizarding world.
In some fanfictions, the Dursleys might be portrayed as having a change of heart. For example, they could start to secretly admire Harry's magical abilities instead of resenting them. This can add an interesting twist to the original story.
One factor that can make the Dursleys good in fanfiction is guilt. They might feel guilty for how they've treated Harry over the years. This guilt could drive them to change their ways and be more loving and accepting towards him.
Often, a good Dursley in fanfiction is the result of a different backstory. Maybe Petunia has a moment of reflection about her sister Lily and decides to treat Harry better. Vernon could also come around when he sees the power and influence that Harry might have one day and wants to be on his good side. So, in these fanfictions, they become more likeable and positive characters.
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.
A good Dursleys fanfiction often gives them more backstory. In the original books, we don't get much about their lives before Harry came to live with them. Fanfictions can fill in those gaps. For example, exploring how Vernon got his job and how Petunia managed the household finances. Also, a good fanfiction might change their relationship with Harry in a believable way. Maybe Harry discovers a family heirloom that makes the Dursleys see him as part of the family. It's all about adding depth and new perspectives to their characters.
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.
Well, in fanfiction, the idea of 'ridge ribs' and the Dursleys' abuse of Harry Potter could be a completely out - of - the - box concept. Maybe 'ridge ribs' are part of a spell or a magical object that the Dursleys get their hands on. And they use it to make Harry's life even more miserable. It could be that the 'ridge ribs' have some sort of power to cause pain or discomfort, and the Dursleys, being the horrible people they are in the story, take advantage of it to abuse Harry. But this is all just speculation based on the very unique combination of words in the fanfiction world.