Her relationship with the Hogwarts professors could be interesting. Some, like Dumbledore, might have known about her all along but kept it a secret for her protection. So, she could feel a sense of betrayal at first but then understand his reasons. As for Snape, he might be particularly harsh on her because of her Black heritage, but she could prove him wrong with her kindness and courage. Among the students, she could form a clique with those who are outcasts or misfits, and together they could face the challenges of Hogwarts life.
In relation to the Order of the Phoenix members, some would welcome her with open arms as they were friends of her father. However, others might be wary as they don't know if she can be trusted. Her relationship with Sirius's old friends like Lupin would be complex. Lupin might see a lot of Sirius in her, which could be both a comfort and a pain for him. She could also have an unexpected bond with Kreacher. At first, Kreacher might resent her as another Black, but as she shows her different nature from the other Blacks he has known, he could become her ally.
One possible plotline could be the daughter's discovery of her true identity. Maybe she was raised in an ordinary Muggle family and suddenly strange things start to happen. She begins to show magical abilities and then discovers she is Sirius Black's daughter. Another plot could involve her search for her father's legacy within the wizarding world, facing both friends and foes along the way.
At first, they might be cautious around each other. Harry, having known Sirius, would be curious about his daughter but also a bit reserved. As they start to work together on small tasks in Hogwarts, like helping out in Dumbledore's Army - like activities, they'd begin to trust each other more. Eventually, they could become very close friends, sharing secrets and relying on one another in dangerous situations.
It could develop in a complex way. The spanking incident might initially create tension between them. Harry could be angry or resentful towards Sirius at first.
In this fanfiction, Harry would start to show his softer side more often. His love for Sirius' daughter would make him more open to emotions. Sirius' daughter would develop her magical skills further under Harry's guidance. She would also become more politically aware as she is now part of the Potter family. They would develop as a couple by supporting each other through tough times, like when dealing with old enemies or new threats to the wizarding world. Their development would be intertwined, and they would bring out the best in each other.
Obviously, the daughter of Sirius Black is the main character. She is often depicted as having some of her father's rebellious spirit. Her friends at Hogwarts also play important roles, like her best friend who might be from a different house, adding an element of inter - house friendship.
One idea could be that Sirius Black's daughter, who has been hidden away all this time, discovers her true identity while trying to break into Azkaban to clear her father's name. She could have some unique magical abilities that help her in this dangerous quest.
There probably is. The Harry Potter fandom is huge and full of diverse ideas. Writers might explore this idea to add new twists to the story, like how Harry's relationship with Sirius would be re - imagined if he were his daughter, and how it would change the overall plot dynamics.
At first, it might be a bit rocky. Harry is used to a more structured upbringing at the Dursleys', while Sirius is quite the free spirit. But as time passes, Sirius starts teaching Harry about his family heritage. They go on adventures together, like exploring the Forbidden Forest. Harry begins to see Sirius as a true father figure, and Sirius sees Harry as the son he never had. They also have arguments, like when Sirius is overprotective, but they always work through it, which deepens their relationship.
She could be seeking revenge against those who wronged her father. So she goes to Azkaban, using her father's old contacts and knowledge, to find the real culprits. She might be a powerful witch, with skills in Occlumency to protect her mind from the dark influences in Azkaban.
She might initially have a tense relationship with the Weasley family. Since Sirius was close to them and they are Gryffindors, they might be a bit wary of her. But as time goes on, she could prove herself to them. With Harry, she could be a bit of an enigma at first. Harry might be curious about her and they could form a friendship based on their shared connection to Sirius.