The plot could develop with Harry secretly studying dark magic texts in the restricted section of the library. He might start to have strange dreams or experiences related to the dark magic he's exploring, and he has to be very careful not to get caught by Filch or the teachers.
In the 'Harry Potter Hides He Is Dark' fanfic, Harry could be hiding his dark side by carefully choosing his words. He wouldn't let slip any thoughts or opinions that might hint at his darker tendencies. He might also avoid certain places or people that could trigger his dark side, like staying away from dark magic artifacts or those who practice dark magic openly. And, of course, he could be using Occlumency not just to keep his thoughts private from Voldemort but also to hide his own dark nature from others.
The revelation of Harry being 'dark' would cause chaos in the wizarding world. People who once idolized him would feel betrayed. The Order of the Phoenix might question their support for him. Enemies could use this as an opportunity to turn the public against Harry. His relationship with Ginny would also be severely strained. She fell in love with the 'good' Harry, and this new side of him could be too much for her to handle. Also, it could potentially put Neville or Luna in danger if they continued to support Harry, as they might be seen as associated with his 'darkness'.
He might hide it because he doesn't fully understand his own fascination. Harry has always been on the side of good, but perhaps there are elements of the dark side that seem alluring in a strange way. He could be afraid that exploring these feelings would lead him down a dangerous path, so he keeps it a secret.
Maybe in this fanfic, Harry discovers a prophecy that is related to her gender. To avoid fulfilling a part of it that could lead to disaster, she hides her gender. In the process, she could form new alliances with female students who are more in tune with her new 'female identity'. She might also face challenges in classes like Defense Against the Dark Arts because the teaching methods are sometimes more tailored to male students in the original Hogwarts setup.
Perhaps some traditional pure - blood families who have strict ideas about gender roles in the wizarding world. They might not approve of Harry's actions of hiding her gender and try to force her to conform to the traditional male identity. They could use their influence in the Ministry of Magic or within Hogwarts to make things difficult for Harry.
Dark creatures in Harry Potter fanfic can serve as antagonists. They create conflict and danger for the main characters. For instance, a group of Acromantulas could attack the Hogwarts Express, leading to a thrilling chase and battle.
In Harry Potter fanfics, dark creatures can be really fascinating. Some common ones are Dementors. Fanfic writers often explore their origin more deeply or create new powers for them. For example, a fanfic might describe a Dementor with the ability to transform into a shadow and move undetected in Hogwarts.
In a Harry Potter fanfic, 'the dark dragon' could be a unique creation by the author. It might be a powerful and menacing magical creature that plays a significant role in the story, perhaps being used by dark wizards or having some mysterious connection to the dark arts.
The idea of 'dark desires' in Harry Potter fanfic can also be related to relationships. There could be a character who has a 'dark desire' for someone they shouldn't be with, perhaps due to family feuds or different social standings in the wizarding world. This creates complex and often dramatic relationship dynamics within the fanfic.