There are fanfictions where Harry gets captured by Bellatrix and Narcissa is caught in the middle. She has to decide whether to side with her sister or help Harry. This creates a really tense and interesting plot. For example, in some stories, Narcissa's maternal instincts towards Draco play a role in how she treats Harry.
A lot of fanfictions explore the idea of Harry being able to redeem Bellatrix through some magical means. Narcissa might be involved as she has her own complex relationship with her sister. These stories often delve into the darker aspects of magic and the characters' psyches, showing how they can be changed or influenced.
There's also 'Bellatrix, Narcissa and the Unseen Alliances'. This fanfic explores how the two sisters might have formed secret alliances or had different agendas during the wizarding war. It really brings out their individual personalities and how they interact with other characters from the series.
A popular 'Dark Harry and Bellatrix' fanfiction is 'The Dark Convergence'. This story starts with Harry being disillusioned with the light side and gradually being drawn to Bellatrix's brand of dark magic. Their alliance is shaky at first but then grows stronger as they face common enemies. The fic is really good at exploring the moral gray areas that both characters inhabit when they step into the dark.
One common theme is redemption. Sometimes Narcissa or Bellatrix are given a chance at redemption through their interactions with Harry. For example, Narcissa might start to question the Dark Lord's ways after getting to know Harry better.
There's a fanfiction called 'Bellatrix: The Young Enigma'. In this, the author delves into Bellatrix's family life as a young witch. It shows how her family's pure - blood mania influenced her. It also includes her early encounters with the Dark Lord's ideas, which gradually lead her down the path of becoming one of his most loyal followers. This fanfiction really helps in understanding her complex character better.
I really like 'Time's Ripple: Harry and Narcissa'. In this fanfiction, time travel is used as a device to explore the relationship between Harry and Narcissa in a different era. It delves deep into their characters and how they might have interacted given the different circumstances. The writing style is engaging and it's a great read for those interested in this particular pairing and time travel concept.
One common theme is loyalty. Bellatrix's loyalty to Voldemort and Narcissa's more complex loyalty to her family and sometimes self - preservation create interesting dynamics. For example, in many fanfictions, Narcissa will try to protect her family from Bellatrix's more extreme actions.
I'm not sure there are a lot of such fanfictions that are well - known. However, you could start by looking on platforms like FanFiction.net or Archive of Our Own. Search for the key terms 'Harry Potter', 'Bellatrix', and'slave'. Maybe you'll find some hidden gems that explore this rather dark and unorthodox concept within the wizarding world.
One interesting fanfic could be 'The Unexpected Swap'. In this story, Harry and Bellatrix find themselves in each other's bodies and have to navigate the challenges. Harry, in Bellatrix's body, has to deal with the Death Eaters' expectations, while Bellatrix in Harry's body has to face the Order of the Phoenix. It's a thrilling read as it explores the two very different characters' reactions to this strange situation.
In some fanfictions, the lemon could be used as a metaphor for something in Bellatrix's life. For instance, it could represent something sour or bitter in her past that she is constantly trying to overcome while still being her menacing self in the world of Harry Potter. Writers often use such symbols to add depth to characters, and Bellatrix is a character with a lot of potential for this kind of exploration.
One interesting fanfiction could be 'Narcissa's Time - Twist'. In this fic, Narcissa travels back in time and tries to change the fate of the Black family. It's a really engaging read as it delves deep into Narcissa's character and her motives.