No, it's not really ethical. Harry, Parvati, and Ron are beloved characters from the Harry Potter series. Bashing them in fanfiction means creating stories that are often full of negative and untrue portrayals. It goes against the respect that fans should have for the original work and its characters.
Yes, it can be common in some fandoms. In the Harry Potter fandom, for example, there are quite a few 'ron bashing fanfiction' pieces. Since the series has such a large and diverse fan base, different interpretations of characters are bound to happen. Some fans may focus on characters like Harry or Hermione more and see Ron as a hindrance in their relationships or adventures, so they write fanfics bashing him.
Ron bashing fanfiction mainly involves creating fictional stories that are not so kind to Ron. Maybe the author doesn't like Ron's character traits in the original work and decides to rewrite scenarios where Ron is mean, stupid or just not a likable character. It could also be a way to create more drama or tension in a story, especially if it's a love triangle situation where Ron is the odd one out. For example, in some fanfics, Ron might be made out to be a jealous bully to make the other character look better.
Often, these fanfictions might also focus on the flaws of Ron that are exaggerated. This is done to contrast with Hermione's pureblood - associated positive traits. It could be about Ron's insecurities being blown out of proportion, like his jealousy issues, which are then used to make Hermione look better in comparison. And sometimes, it might be about exploring how Hermione's pureblood status could have changed the power dynamics in her relationships throughout the story.
It's hard to say for sure. Fanfiction can cover all kinds of wild and creative ideas. However, the combination of 'Ron bashing' and'mpreg' for Harry and Draco seems a bit extreme. Some fanfiction writers might be interested in exploring such unique and controversial ideas, but it might also be a turn - off for many readers. You might find it by using very specific search terms on fanfiction - dedicated search engines.
Some fics in 'ron weasley bashing fanfiction' have the theme of Ron being a bad boyfriend. They might show him as being neglectful or unfaithful to Hermione, which is a huge deviation from the canon where they had a loving relationship. There are also those that focus on his gluttony, making it seem like his love for food is a major character flaw rather than just a normal part of his personality. And then there are ones that paint him as a social outcast within the Gryffindor house, which is not true as he had many friends and was well - liked in the original story.
Themes in this type of fanfiction often revolve around changing power dynamics. In the original series, Ron was part of the main trio with Hermione and Harry. But in these fanfictions, with Ron being bashed, the power dynamic shifts. Hermione becomes more independent and forms a new alliance with Draco. There's also a theme of alternative Hogwarts. Some fanfictions create a different Hogwarts environment where the relationships between the characters can be explored differently. For instance, a more Slytherin - friendly Hogwarts where Draco has more influence and Hermione is drawn into that world, all while Ron is sidelined due to his negative traits.
One common theme is making Ron out to be a complete idiot rather than the complex character he is in the original. Another could be portraying Hermione as overly bossy and unlikable, which is a far cry from her positive traits in the books. Often, these fictions might also create contrived scenarios to show their relationship in a negative light.
One example could be fanfiction where Hermione is portrayed as overly power - hungry and Ron as completely useless. However, this kind of bashing fanfiction often goes against the original spirit of the characters in the 'Harry Potter' series.
Well, often there's a theme of over - exaggerating their negative traits. In the original stories, Ron has his moments of jealousy and Hermione can be a bit bossy at times, but in these fanfictions, those traits are blown way out of proportion. Also, some might use it as a way to introduce new plotlines that deviate from the canon, like creating conflict between Ron and Hermione that leads to a split in their friendship.