Some fans might create it as a form of shock value. They want to stand out by presenting a very different and controversial take on the relationship between James Potter and Harry.
It could be a result of some fans' desire to break the mold of the typical 'Harry Potter' storylines. The original series has a set of well - established relationships and themes. By creating 'harry potter spanks draco fanfiction', they are trying to create a new and unique narrative that goes against the grain. Also, in some cases, it might be a form of wish - fulfillment for those who have very specific ideas about how they want to see the power balance and interactions between these two characters play out, albeit in a rather controversial way.
There are several possible reasons. Firstly, in the realm of fanfiction, there is a desire to push boundaries. Fans want to see how far they can deviate from the original story while still using the familiar characters. Secondly, it could be a way to express personal views on gender and sexuality. By creating a scenario where Harry Potter is a crossdresser, they are making a statement about the fluidity of gender roles. Additionally, it might be a form of artistic experimentation. Writers may be curious about how the story would change if such a significant alteration was made to the main character's appearance and identity.
One possible reason could be a dark magic influence on James Potter in the fanfiction. Maybe he's been cursed or possessed, causing him to act out of character and disown Harry.
Some people might be interested in exploring the darker side of the characters. In the original 'Harry Potter' series, there are already some difficult and dangerous situations, and these fanfic writers may want to take it to an extreme level. It could also be a way to show how strong the characters are by seeing how they would react to such extreme torture and insanity.
One reason could be a misinterpretation of the characters' struggles. In the original series, the characters face many difficulties, but they always find a way to persevere. However, some fanfiction writers may take those struggles too far and end up with the idea of suicide. Also, there might be a lack of understanding of the impact such content can have on the readers, especially the younger ones.
One reason could be that the author lost interest. Maybe they started with a great idea of a female Harry Potter but then got distracted by other things in life or new fanfiction ideas. Another reason might be that they received negative feedback which demotivated them from continuing.
Well, it might be because some fans feel that Slytherin has been somewhat demonized in the original books. So, they create fanfiction where Slytherin is the victim of abuse, perhaps as a way to give the house more depth and sympathy. Also, the idea of abuse can create a lot of drama and conflict, which are elements that make a story interesting. Fanfiction writers might be using this concept to attract readers who are interested in more complex and edgy storylines. Additionally, it could be a form of exploring the morality and ethics within the Harry Potter universe in a very extreme way.
One reason could be exploring dark themes in the Harry Potter universe in a more extreme way. Some fans might be interested in delving into the psychological struggles that could potentially exist in that world, even if they are very dark. Another reason could be a form of catharsis for the authors, who may be dealing with their own internal issues and using the fanfic as a way to express their feelings in a fictional context.
Some people might create such fanfiction for the shock value. It's a very different and unexpected take on the characters. They want to see how they can twist the traditional story.
One reason could be the complex relationship between them. Snape's mixed feelings of resentment and a strange sense of protectiveness towards Harry in the original series can be explored more deeply in fanfiction through fantasies. Another reason might be the popularity of both characters. Fans want to see different interactions between them that were not fully shown in the books.