You can start by looking on popular fanfiction websites such as Archive of Our Own (AO3). It has a large collection of Harry Potter fanfictions, and you can easily search for ones that involve Harry and Sirius Black in a time - travel scenario using the search bar.
One great fanfiction could be where Sirius Black travels back in time to prevent his own imprisonment in Azkaban. He might use his knowledge of the future to avoid being framed by Peter Pettigrew. This could change the entire course of the story, as Harry would then have a more stable and present godfather figure in his life from an earlier stage.
In some fanfictions, Sirius Black time travels to the past and teams up with his younger self. They work together to expose the Death Eaters' plans earlier. This creates a really cool dynamic as the older Sirius has more experience and the younger one has more energy and impulsiveness.
The theme of second chances is also prevalent. In time travel stories, both Harry and Sirius may get opportunities they missed in the original timeline. For example, Sirius could save his friends who died earlier. And also, the exploration of the past and how it shapes the future is a key theme. They go back and learn things that change their perspective on the present and future of the wizarding world.
One interesting story could be where Harry travels back in time and teams up with a young Sirius Black to prevent some of the tragedies that later befall the wizarding world. They might use their combined knowledge of the future and Sirius' skills as an Animagus to outwit dark wizards.
There's also 'Time's Twist' which delves deep into how time travel affects the relationship between Sirius Black and Harry Potter. The author does a wonderful job of exploring the emotional side of their connection as they navigate through different time periods together. It's full of interesting plot twists and character development.
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.
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.
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.