One common plotline is Hermione being captured by Bellatrix and forced into a situation where she has to act like a pet. For instance, Bellatrix might use a spell to make Hermione obey her every command.
Another plotline could be Hermione trying to infiltrate Bellatrix's lair in the guise of a pet. She might transform herself or be magically altered to look like an animal, and then she has to navigate Bellatrix's world while in this form. It could be a very dangerous and exciting adventure as she tries to gather information or find a way to defeat Bellatrix from the inside. There are also fanfictions where Hermione is trying to rescue someone who has been turned into a pet by Bellatrix, and she has to face Bellatrix directly to do so.
There are plotlines where Bellatrix discovers Hermione's potential as a powerful witch and decides to keep her as a pet - like captive to study her magic. Hermione then has to find a way to escape while also dealing with Bellatrix's unpredictable and often cruel behavior. In some fanfictions, this situation also leads to an exploration of Hermione's darker side as she has to fight for her freedom in a very hostile environment created by Bellatrix.
One of the main themes is transformation. Hermione, who is usually a strong - willed and independent character, is transformed into a 'pet' in this fanfiction concept. This shows how characters can be changed by extreme circumstances. There's also the theme of captivity and freedom. Hermione is in a form of captivity, and the fanfictions may explore her attempts to gain freedom or how she copes with the lack of it. And of course, the theme of the relationship between good and evil is also present, as Bellatrix represents evil and Hermione is a symbol of good in the original series.
One common theme is power imbalance. Bellatrix has the power as a Death Eater, and Hermione is in a submissive position as a 'pet'. Another theme could be the exploration of Hermione's resilience. Despite being in such a demeaning situation, she tries to resist and find a way out.
Often, Hermione's intelligence is pitted against Bellatrix's madness. The fanfiction might show Hermione trying to outwit Bellatrix while Bellatrix uses her dark magic to keep Hermione under her thumb, like a pet in a way. For example, Bellatrix could be using some dark spell to control Hermione's actions, and Hermione has to use her wits to break free.
A great plotline is the redemption arc. Bellatrix, known for her extreme cruelty, could be influenced by Dark Hermione. Hermione might be on a path to use dark magic for what she believes is a greater good, and Bellatrix could see this as a way to redeem herself. This could lead to a lot of internal conflict for Bellatrix as she struggles with her past actions and tries to follow Hermione's lead. There could also be a plotline where they explore the limits of dark magic together. They experiment with spells and incantations that no one has dared to try before, and this exploration could either lead them to great power or their downfall.
Survival is a prevalent theme. Given Bellatrix's murderous and unpredictable nature, Hermione often has to fight for her survival in these fanfictions. It could be a physical fight, or a mental battle as she tries to outmaneuver Bellatrix in a dangerous situation.
A common theme is power struggle. Bellatrix is a powerful and dark witch, and Hermione is also very powerful in her own way with her intelligence and magic skills. So, there's often a back - and - forth as they try to assert their influence over situations or each other.
One possible plotline could be that Bellatrix captures Harry during one of his adventures and decides to keep him as a pet for her own amusement. She might use dark magic to bind him and make him obey her commands. Another could be that in an alternate reality, Harry is somehow magically enslaved to Bellatrix from the start, and the story follows his attempts to break free from her control while she uses him for various dark purposes, like spying on the Order of the Phoenix.
A possible plotline could start with Bellatrix having a strange fascination with Harry from the start. She manages to get him in her clutches and treats him like a pet. Harry, on the other hand, uses his wits and the limited magic he can access in this state to outsmart Bellatrix. There could be a lot of psychological battles between them, with Harry trying to understand Bellatrix's twisted mind while she tries to break his spirit. And all this could be set against the backdrop of the ongoing war between the good and the evil in the wizarding world.
One possible plotline could be that Bellatrix, in a moment of unexpected self - reflection, decides to save Hermione from a dangerous dark magic experiment that the other Death Eaters are planning. Maybe she has a change of heart because she sees a bit of herself in Hermione's intelligence and determination.
Redemption is also a theme. There are fanfictions where Bellatrix has a chance at redemption through her relationship with Hermione. Maybe Hermione sees something in Bellatrix that others don't and tries to bring out the good in her. It's an interesting way to explore the character of Bellatrix beyond her villainous role in the original books.