One common theme is redemption. Draco, with his past actions during the war, often goes through a process of redeeming himself, and Fleur can be a part of that journey. For example, in some fanfics, she helps him come to terms with his mistakes.
The theme of cultural differences also often appears. Fleur being part - Veela and from a different wizarding culture than Harry adds a layer of complexity. Their interactions can involve misunderstandings at first but then growth as they learn about each other's cultures.
The theme of unexpected love also pops up a lot. Given that in the original series, there's no real indication of a relationship between them, fanfiction writers like to explore how they might fall in love. It could start from a simple friendship or a shared experience that suddenly makes them see each other in a new way.
One common theme is their love story. How they met, fell in love, and overcame challenges to be together.
One common theme is acceptance. Hermione being a werewolf is not an easy thing in the wizarding world, and Fleur's acceptance of her is a big part of these stories. For example, in many fics, Fleur has to defend Hermione from those who would shun her.
One common theme is the exploration of their relationship. Since they don't have a major relationship in the original books, fanfiction often delves into how they could get closer, whether it's through shared magical interests or facing a common enemy.
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.
Love at first sight is a common theme. Their initial meeting often sparks an immediate attraction that is both physical and emotional.
One common theme is the idea of unexpected relationships. Given that Harry and Fleur don't interact much in the original series during the Triwizard Tournament, fanfictions often explore the possibility of a closer bond between them, whether it be friendship or something more romantic.
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.
One common theme is the anticipation of a new life. It often shows Bill and Fleur excited and a bit nervous about becoming parents.