The plot could revolve around the daughter's relationships. She may have a difficult time making friends at Hogwarts because of her mother's reputation. However, she meets a group of outcasts who accept her for who she is. Together, they embark on a journey to rewrite the story of the Lestrange family. She might also have a love interest who helps her see the good in herself despite her family's dark history.
Well, the fanfic could be about how Bellatrix's daughter discovers her mother's true nature as she grows up. Maybe she was hidden away and raised by someone else. As she uncovers the truth, she has to decide whether to embrace her family heritage or reject it completely. She could also have unique magical abilities that set her apart from others in the story.
Bellatrix was extremely cruel and devoted to the Dark Lord. Her daughter could be the opposite. Maybe she has a kind heart and is repulsed by the dark magic her mother practiced. She could be more empathetic towards others, especially those who were victims of the Death Eaters.
Well, in a 'Harry impregnates Bellatrix' fanfic, it might explore the chaos that would ensue in the wizarding world. Harry's friends would be horrified and confused. Bellatrix, being who she is, might have her own dark motives for allowing or even causing such a situation. It would be a very complex and disturbing story that would likely rewrite many established character traits and relationships in the 'Harry Potter' universe.
The plot could involve the son trying to redeem his mother's name. He might go on a journey to find out more about her past, hoping to understand why she became so evil. Along the way, he meets various characters who knew his mother and has to deal with their mixed reactions towards him.
Redemption is also a frequent theme. Since Bellatrix was a Death Eater, the daughter might strive to make up for her mother's wrongdoings or at least prove that she is not like her. For example, she could be involved in helping the victims of the Death Eater attacks. This theme adds depth to the character and the story.
The plot could involve Bella being raised in the Twilight world without knowing her real mother. Then, through some magical event, she finds out she's Bellatrix's daughter. This could lead to a conflict as she tries to figure out where she truly belongs, between the two very different worlds of vampires and wizards. Also, there could be a plotline where she has to face the dark legacy of her mother and decide whether to embrace or reject it.
A plot might involve Harry being captured by Bellatrix. Instead of harming him immediately, she is intrigued by his power. She tries to break his spirit but Harry resists. Over time, through their power struggles and intense conversations, a strange connection forms between them that changes their relationship in unexpected ways.
Perhaps in the fanfic, Bellatrix is under the influence of some dark magic that forces her to curse herself in this way. It could be part of a larger plot where her enemies discover her in this state and use it to humiliate her. Since lactation is not a normal state for a witch like her, it would be a great source of embarrassment and vulnerability in a world full of rivalries and power struggles.
If Hermione were Bellatrix's daughter in the fanfic, it would make for a very interesting plot twist. Hermione might struggle with her identity, being raised in the wizarding world as a 'good' witch but having such an evil mother. It could lead to her being ostracized by the wizarding community. Also, her skills in magic could be different. She might have an innate understanding of the Dark Arts that she has to constantly fight against.
Another theme is redemption. Many fanfics explore the idea of the daughter trying to atone for her mother's sins or break free from the cycle of evil that her mother was a part of. For example, she might try to use her magic for good instead of following in Bellatrix's footsteps.
Maybe Harry is in a dire situation where he needs a powerful source of magic to defeat Voldemort, and Bellatrix's magic seems like a viable option.