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.
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 interesting fanfiction could be about Bellatrix's early years at Hogwarts. It might explore her friendship or rivalry with other Slytherins. Another could be a story where Bellatrix has a change of heart after a magical encounter and tries to redeem herself. And there could also be a fanfic that focuses on her relationship with Voldemort in a more in - depth way, showing the power dynamics and her unwavering loyalty.
One interesting fanfiction could be about Bellatrix's early years at Hogwarts and her first encounter with a young Harry Potter in a magically altered scenario. It might explore how their paths could have crossed in a different way than in the original books.
One interesting fanfiction could be where Bellatrix has a change of heart due to some magical accident and ends up helping Harry Potter secretly. In this type of story, there could be a lot of internal conflict for Bellatrix as she battles her loyalty to Voldemort and her newfound sense of morality. Another might be a time - travel fanfic where Harry goes back in time and has to deal with a younger Bellatrix, trying to prevent her from becoming the dark witch she is in the original timeline. There are also fanfictions that explore a more complex relationship between them, perhaps a forbidden friendship that develops against all odds.
Perhaps a plotline where Harry discovers the truth about his parentage later in life. He has been raised believing Bellatrix is his mother, but then uncovers evidence that it's all a complex web of dark magic and deception. This could lead to a journey of self - discovery as he tries to figure out who he really is and where he belongs in the wizarding world, all while dealing with the stigma of being associated with Bellatrix Lestrange.
One idea could be exploring how Bellatrix's pregnancy affects her loyalty to Voldemort. Maybe she starts to question some of his more extreme actions as she thinks about the future for her unborn child.
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.
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.
A possible plot could be that Rodolphus Lestrange, having some remorse after Voldemort's defeat, tries to make amends by approaching Harry Potter. Harry is initially skeptical but then realizes that Rodolphus has some valuable knowledge about dark magic artifacts that could be a threat if they fall into the wrong hands. So they form an uneasy alliance. Also, there could be a plot where a spell gone wrong during a fight between Harry and Rodolphus causes them to swap minds for a short time, leading to humorous and also tense situations as they have to navigate each other's lives.
One plot idea could be that Rabastan, in an alternate universe, is forced to team up with Harry Potter to fight a common dark magic threat that endangers both the wizarding world and the Death Eaters' own interests. This would create a lot of tension as they have to overcome their natural enmity.