Well, perhaps they form a secret society within Hogwarts that promotes dark magic. They recruit students who feel left out or who have a thirst for more power. Dark Hermione could use her knowledge of spells and Dark Fleur her charm and allure to draw in followers. And then there could be a conflict when the other students and teachers start to suspect something and try to stop them.
A possible plot could involve Dark Hermione and Dark Fleur being sent on a mission by a powerful dark wizard. They have to retrieve a powerful dark artifact. Along the way, they face various challenges and obstacles, and their relationship is tested. They might also have to fight against other dark wizards who also want the artifact, and in the end, they either succeed together or one of them betrays the other for the power of the artifact.
Another plot could involve them facing opposition from the traditional good side, like Dumbledore's Army remnants. They have to use their newfound dark powers and cunning to outwit their opponents. Maybe they start to realize that the line between good and evil isn't as clear as they once thought. As they fight, they also discover secrets about the wizarding world's past that make them question everything they knew.
One plot idea could be Snape having to protect Hermione from a dark magic threat that is targeting her specifically. Maybe he initially resists the idea but gradually realizes her importance. Another could be a time - travel plot where Hermione goes back in time and has to work with a younger, even darker Snape to change some crucial events in the wizarding world. And a third idea might be that Snape and Hermione are forced to team up in a dangerous underground magical tournament where they have to rely on each other's skills to survive.
Another plot could be set in an alternate universe where Sirius never went to Azkaban. He and Hermione meet when she is a young, brilliant witch just starting at Hogwarts. Sirius, being a bit of a rebel, takes Hermione under his wing and they embark on adventures outside of the school rules, exploring the Forbidden Forest together and uncovering secrets about the wizarding world that are not taught in classes.
One interesting fanfiction could be 'The Dark Alliances' where Dark Hermione teams up with Fleur in a world full of magic and mystery. It delves into their complex relationship as they face various challenges.
One plot idea could be that Draco discovers Hermione has a connection to the Dark Mark against her will. Maybe she was cursed with it during an encounter with Death Eaters. Draco, having some knowledge of the Dark Arts, decides to help her get rid of it secretly, which would lead to many tense and secretive meetings between them as they try to figure out how to break the curse without getting caught by either side.
One plot idea could be that Draco, as the Dark Lord, has a change of heart when he realizes Hermione's intelligence and compassion. He starts to question his dark ways and secretly tries to protect her from the other dark forces. Another could be a time - travel plot where Hermione goes back in time and tries to prevent Draco from becoming the Dark Lord. Or perhaps they are forced to work together on a dangerous magical mission, and along the way, they develop an unexpected bond.
One plot idea could be that Dark Naruto forms an alliance with Dark Kyuubi to take over the Hidden Leaf Village. They use their combined dark powers to manipulate the villagers and turn them against each other. Another idea is that they embark on a journey to find a powerful, ancient artifact that can enhance their dark abilities even further. Maybe they face off against the original Naruto and Kyuubi in a final battle of good versus evil.
Often, Dark Hermione's character is developed by showing her descent into the dark side. Maybe she starts to question the limitations of the 'good' magic she has been taught and becomes frustrated. For Dark Fleur, it could be through her desire for more power and recognition. Her beauty and confidence could be turned into tools for her dark pursuits.
One common theme is the exploration of power. In a dark setting, both Hermione and Fleur might seek power in different ways, and their relationship can be shaped by this pursuit. For example, they could be vying for a position in a dark wizarding order.
One common theme could be competition. Since both Hermione and Fleur are strong - willed characters, in dark fanfiction, this could be turned into a cut - throat competition that goes beyond the normal rivalry. For example, they might compete for a powerful magical object in a way that involves underhanded tactics.