A possible plotline could also be the Black sisters' own personal growth and development. They might start off with certain beliefs and values influenced by their family's dark reputation, but as the fanfiction progresses, they could change and become more independent thinkers, perhaps even turning against some of the family's more evil traditions.
One interesting plotline could be the exploration of the Black sisters' relationships before and during the events of the Harry Potter series. For example, how Bellatrix's loyalty to Voldemort affected her relationships with Narcissa and Andromeda. Another could be a story where the sisters have to team up to protect a family secret related to the Black family heritage. Maybe a plot where they interact with Harry Potter in a way that wasn't shown in the original books, like helping him uncover some dark magic that has a connection to the Black family.
Another possible plotline is that the Sisters Black are outsiders in the wizarding world due to their family's reputation. But they meet Harry, who also has a bit of an outsider status in some ways. Together, they try to change the perception of their families in the wizarding community while also dealing with the normal Hogwarts adventures like Quidditch, classes, and the Forbidden Forest.
Another plotline could be their connection to the wider wizarding war. Maybe they have some secret knowledge or a role to play that was not fully explored in the original books. They could be involved in some behind - the - scenes operations during the war, either on the side of the Order of the Phoenix or Voldemort's forces in a more complex way than just being simple followers.
Perhaps a plot where Orion Black and Harry Potter team up to fight against a new dark threat in the wizarding world. Orion's experience and Harry's unique skills could make for an exciting adventure.
One interesting plotline could be a secret mission to uncover a hidden dark magic artifact that the Ministry of Magic has been covering up. The characters might have to use their stealth and unique skills to navigate through dangerous areas.
One common plotline is Sirius Black escaping from Azkaban earlier and secretly training Harry in advanced magic. Another could be Sirius and Harry going on a hidden adventure to uncover more about Harry's parents. There are also stories where Sirius plays a more active role in the fight against Voldemort at Hogwarts, using his knowledge of the Dark Arts and his Animagus form to their advantage.
In some Black Phoenix Harry Potter fanfiction, the Black Phoenix might be a symbol of a long - lost prophecy. This could lead to Harry having to go on a quest to uncover the meaning of the prophecy and how it relates to his battle against Voldemort. It could involve him delving into ancient magic that has been forgotten for centuries.
One interesting plotline could be the discovery of a long - lost Black family heirloom that holds great power. The heir might find it and have to learn how to use it while also dealing with the expectations of the Black family legacy. Another could be the heir's struggle to balance their loyalty to the Blacks with their friendships at Hogwarts, like with Harry and his friends.
Perhaps in the fanfiction, Harry as Lord Potter - Black has to deal with the dark secrets of the Black family while also maintaining his own moral compass as a Potter. This could involve unearthing old family feuds and trying to make amends, all while fighting against the ever - present threat of Voldemort or other dark forces.
In some 'Harry Potter Heir Black fanfiction', a possible plotline is the heir's struggle to reclaim the Black family's honor. After all the dark deeds associated with some members of the family, the heir tries to rewrite the family's story. They might use their inheritance, whether it's a powerful magical artifact or a special spell, to do good deeds and change how the wizarding community views the Black family.