It could be Bellatrix Lestrange. Since she is a Death Eater and has a personal vendetta against Sirius, she would be a great antagonist. She might try to kill Sirius again and also target Harry to please Voldemort.
In a 'Harry Potter meets Sirius Black fanfiction', it could be interesting if Sirius and Harry found a way to time - travel. They could go back to the time when James and Lily were alive. This would not only allow Harry to meet his parents but also give Sirius a chance to change some events that led to his downfall. They might also interfere with the actions of Voldemort in the past, creating a whole new timeline and a different future for the wizarding world.
Fanfiction about these three can take many forms. For example, there could be time - travel fics where Harry goes back in time and meets Regulus and Sirius when they were younger. This could lead to all sorts of interesting plot twists, like Harry trying to prevent Regulus from joining the Death Eaters in the first place. Or it could be a fic where Sirius survives and he and Harry explore the secrets of the Black family together, including things that Regulus left behind. There are also fics that focus on the emotional bonds between the characters, showing how the different personalities of Regulus, Sirius, and Harry interact and influence each other.
One possible reason could be a misunderstanding. Maybe some false information was spread about Harry that made Sirius believe he had done something unforgivable. For example, if there were rumors that Harry was involved with dark magic in some way, Sirius, who has a strong aversion to the dark side, might be quick to disown him.
One great 'Harry Potter Sirius Black fanfiction' is 'Padfoot Returns'. It really delves into Sirius's character and his relationships within the wizarding world. The story has a great plot that keeps you hooked from start to finish.
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.
In some fanfiction, yes. Fanfiction writers often like to play with the relationships in the Harry Potter universe. They might create a scenario where Sirius Black is Harry Potter's father, perhaps exploring how this would change the story's dynamics, the relationships between characters, and the overall plot.
Well, a popular one is 'Sirius and Harry: A Different Kind of Family'. In this fanfiction, Sirius actually gets a chance to be a proper father figure to Harry. It shows their relationship evolving in a very heartwarming way. There's also 'The Sirius - Harry Connection'. This one plays around with the idea of a magical bond between them that goes deeper than what was shown in the books. And 'Harry's Refuge with Sirius' where Sirius provides a safe haven for Harry during tough times at Hogwarts.
One great 'Harry Potter x Sirius Black fanfic' is 'The Marauders' Reunion'. It beautifully captures their relationship and the magic of the wizarding world. Another is 'Sirius' Redemption' which delves deep into Sirius' character in relation to Harry. And 'Bond Beyond Blood' shows a really interesting take on their bond that goes beyond the typical mentor - mentee relationship.