Perhaps a story where Bellatrix has a change of heart early on. She meets James Potter in a secret encounter and is impressed by his ideals. This encounter makes her question her loyalty to Voldemort. As they interact more, they develop a friendship that challenges the boundaries of the light and dark sides in the wizarding world. James has to decide if he can trust her and Bellatrix has to figure out how to break free from the dark path she's on.
A plot could revolve around a time - travel accident. James Potter is sent back in time and ends up in Bellatrix's era. Bellatrix, being intrigued by this strange wizard from the future, decides not to turn him in immediately. Instead, they start to learn from each other, with James trying to understand the roots of the dark side she represents and Bellatrix getting a glimpse of a different kind of magic and values.
Another plot could be a time - travel fanfiction. James Potter somehow travels to a time when Narcissa is young and in a difficult situation. He decides to help her, and in the process, they form an unexpected bond. This bond then has consequences for the future as James returns to his own time.
One idea could be that Harry discovers his true parentage and has to struggle with his identity. He might be torn between the side of good that he has known all his life and the dark legacy of Bellatrix. Another plot could involve him facing discrimination from both the wizarding world that hates Bellatrix and the Death Eaters who might see him as a tool or a threat. For example, he could try to use his knowledge of Bellatrix's magic, which might be more complex and dark - tinged, to fight against Voldemort in a different way than in the original story.
One plot idea could be that Bellatrix, in an alternate reality, has a change of heart and decides to protect Hermione from other dark forces. Maybe she sees a bit of herself in Hermione's fierce determination. Another could be that Hermione, while researching dark magic for a school project, accidentally stumbles upon a long - forgotten connection between her family and Bellatrix's, leading to a strange alliance. And a third idea might be that Bellatrix is cursed and Hermione is the only one who can break the curse, but in the process, they have to face their deep - seated prejudices about each other.
One idea could be a story where Bellatrix has a moment of doubt about Voldemort's methods. Maybe she starts to see the destruction he's causing and has to decide whether to stay loyal or turn against him. And Harry Potter could somehow be involved in this internal struggle of hers, perhaps by showing her a different path through his own actions and values.
One idea could be a time - travel plot where Hermione somehow gets sent back in time and has to deal with a younger Bellatrix. Maybe she tries to change Bellatrix's path to the dark side. Another could be a magical duel between Hermione and Bellatrix where Harry is caught in the middle, forced to choose which side to help. Or a plot where Bellatrix, under some sort of spell, has to team up with Hermione and Harry to fight a greater evil.
One idea could be exploring Bellatrix's backstory before she became a Death Eater. Maybe she had a complex relationship with her family that led her down the dark path. Another could be a story where she has a change of heart, perhaps due to an unexpected encounter with a character like Harry Potter. For example, she could see some of her own past self in Harry and start to question her loyalty to Voldemort.
A really interesting plot could be Bellatrix being given a chance at redemption. In this fanfiction, she could start to question Voldemort's motives after seeing the destruction he causes. She might then try to secretly help the Order of the Phoenix. Also, a plot about her teaching a young Death Eater the ways of the Dark Arts and having second thoughts about it mid - way through could be fascinating.
One idea could be a time - travel plot where Harry somehow travels back in time and has to interact with Bellatrix in her younger days. This could lead to him trying to change her path before she becomes a Death Eater.
Some fanfics explore Bellatrix's family relationships more deeply. Like her relationship with Narcissa. There could be a plot where Bellatrix has to choose between loyalty to Voldemort and protecting her sister, which adds a lot of emotional depth.
Well, it could be that Fem Harry Potter is actually a long - lost relative of Bellatrix's family. Bellatrix initially hates her because of her association with Dumbledore and the Order. But as the story progresses, they find out some dark family secrets that connect them. They then have to decide whether to keep fighting against each other or team up against a greater evil, like a new dark wizard who is more powerful than Voldemort and is threatening the wizarding world.