It's controversial. The Dursleys were Harry's only family (albeit a horrible one) in the Muggle world. Killing them in fanfiction is a very dark take. It's not common because most fanfiction either focuses on the magical adventures, Harry's relationships at Hogwarts, or redeeming the Dursleys rather than such extreme and immoral actions. The original series promotes forgiveness and growth, not revenge - killing.
It's a very controversial theme. In the original 'Harry Potter' series, both Snape and Dumbledore are complex and important characters. Dumbledore is a mentor figure to Harry, and Snape has a very complicated relationship with Harry as well. For fans who love the original story, the idea of Harry killing them goes against the essence of the characters' development and the overall moral and emotional fabric of the series.
It's a rather controversial theme. In the original 'Naruto' series, Naruto and Sasuke are friends and rivals. Their relationship is complex and central to the story. So, a fanfiction where Naruto kills Sasuke goes against the essence of their bond. Many fans who love the original dynamic would find it unacceptable as it's a major deviation from what they expect and cherish in the Naruto - Sasuke relationship.
It's a very controversial theme. Naruto is a character known for his will to protect and his bonds with the villagers. In the original story, he wants to be recognized and respected by the villagers, not harm them. So such a fanfiction goes against the core of his character, which is why it would be considered quite controversial.
It's not that common. Most fanfictions tend to follow the general positive or at least not so extreme paths for the main characters. Since Sasuke and Sakura are main characters, having her kill him would be a huge deviation. However, some writers might explore this in a 'what - if' scenario, like if Sakura was mind - controlled or in an alternate universe where their relationship turned out completely different.
This type of fanfiction is very controversial. Naruto represents hope and growth in the series. Kakashi, as his teacher, is supposed to guide and protect him. Having Kakashi kill Naruto would completely disrupt the established character arcs and the overall positive message of the 'Naruto' story. It might only appeal to a very small subset of fans who are interested in exploring extremely dark and alternative scenarios.
In the world of fanfiction, the idea of Harry Potter killing the Dursleys' child is extremely dark and unethical in the context of the original series' values. Harry was raised by the Dursleys, albeit unpleasantly, but he has a moral compass that would not lead him to such a heinous act. Fanfiction that explores such extreme and immoral concepts can be disturbing and goes against the spirit of the Harry Potter universe.
It's not common in the sense that it goes against the norm. In most official Batman storylines, Batman is the symbol of justice that endures. However, in the realm of fanfiction, some writers explore this dark and edgy concept to explore different character arcs, power dynamics, and moral ambiguities. It challenges the established order and makes readers question their assumptions about the characters.
It's not a super common theme but it does exist. The motives could also be related to a dark turn in Harry's character. Maybe in these fanfictions, Harry is influenced by dark magic or has been pushed too far by the Dursleys' constant mistreatment. He might see killing them as the only way to break free from the chains of his past. But this goes against the core values of the original series which promotes forgiveness and love in the face of adversity.
It's not common at all. The Harry Potter world is mainly associated with magic, friendship, and fighting against evil. Suicide is a dark and heavy topic that doesn't really fit with the general feel of the franchise. Most fanfiction focuses on expanding on the existing adventures, relationships, or exploring new magical elements rather than such a negative and out - of - character scenario.
It is a rather controversial theme. In the Harry Potter fandom, Harry is a beloved main character. Having Draco kill him goes against the general heroic narrative and the idea of good triumphing over evil that is prevalent in the original series. Most fans prefer fanfics that stay true to the spirit of the books, where Harry is the hero and Draco is more of an antagonist who may reform, not a murderer.