Perhaps there are power dynamics at play. As a Black heir, Harry could be involved in complex family politics. For example, he may face different expectations compared to when he was just known as Harry Potter. There could be rivalries within the family for the inheritance or influence that comes with being the heir.
One interesting plot point could be how Harry discovers he is the heir of Black. Maybe it's through some hidden family artifacts or a revelation from an old family member. Another could be how this new identity affects his relationships at Hogwarts, like with his friends Hermione and Ron.
One interesting plot point could be how Harry's upbringing by Arcturus Black changes his perception of the wizarding world. Maybe he's taught different magic than what he would have learned at the Dursleys or Hogwarts. Another could be how his relationships with other characters, like Sirius, are altered. Since Arcturus is an older Black family member, he might have different views on family loyalty compared to Sirius.
Well, perhaps a major plot point is how Harry's relationship with the wizarding world changes. Since he is raised by Cassiopeia Black, he might have a different standing in the pure - blood society. He could be more involved in the Black family affairs and politics within the wizarding world from a young age, which would greatly influence his view of the world and his future actions.
A possible plot point is the reaction of the wizarding world to Harry being the heir of Merlin. Some might see him as a savior, someone who can bring about a new golden age of magic. Others, out of jealousy or fear of change, could try to undermine him. His friends, like Hermione and Ron, would likely support him but might also be in awe of his new status. And there could be a search for more knowledge about Merlin's legacy, which could take Harry on adventures to long - forgotten places in the wizarding world.
Well, one interesting plot point could be the discovery of new magical abilities. Maybe the heir has a unique power that has been lost in the wizarding world for centuries. Another could be the heir's relationship with the Hogwarts founders' legacies, like finding hidden chambers or secrets related to them.
Well, one interesting plot point could be the exploration of the dark magic heritage. Maybe the so - called 'Heir of Darkness' discovers ancient and forbidden spells that were long lost. Another could be the character's internal struggle between the allure of dark power and the loyalty to the good side like Harry Potter and his friends represent.
One interesting plot point could be how Fem Harry discovers she is the heir of Lefay. Maybe there are hidden magical artifacts or prophecies that lead to this discovery.
Well, one interesting plot point could be the discovery of the true nature of the Heir of Death. Maybe it involves a hidden power or a special connection to the wizarding world's ancient magic. Another could be how the main character, perhaps Harry, interacts with this newfound identity and how it changes his relationships with his friends like Ron and Hermione.
Well, obviously Harry Potter himself is a main character. Since he is being raised as a Black heir, Sirius Black could play a very important role. He could be the one guiding Harry in understanding his new identity as part of the Black family.
In such a fanfiction, a possible plot point is his social interactions. He might be more isolated at first because of his unusual upbringing. However, this could also lead to him making very strong and loyal friends later. Also, his skills in magic might be more focused on defensive and survival magic, given his snake - raised background.