One great example could be a fanfiction where Sirius Black arrives just in time to save Harry from a group of Death Eaters. He uses his Animagus form to surprise the attackers and whisks Harry away to safety. Another might involve Sirius rescuing Harry from a dangerous situation in the Forbidden Forest, using his knowledge of the area and his magical abilities.
There are fanfictions where Sirius Black rescues Harry Potter from a situation within Hogwarts itself. For instance, when Harry is wrongly accused of something by the school authorities or is in danger from a dark magic experiment gone wrong in the castle. Sirius, with his loyalty to Harry, manages to break into the school (using his skills and determination) and gets Harry out of harm's way. In some fanfictions, he also provides Harry with important information during the rescue, which helps Harry in future adventures.
In some fanfictions, after Sirius escapes Azkaban, he and Harry start to bond through their shared love for James Potter. Sirius tells Harry stories about his father that no one else knew, which brings them closer. There are also fanfictions where they bond during the time when Sirius is in hiding at Grimmauld Place. They have heart - to - heart talks and Sirius gives Harry advice on dealing with the pressure of being 'The Chosen One'.
In some fanfictions, Sirius' character develops a greater sense of responsibility. When he rescues Harry, he realizes how important it is to be there for him, not just in times of physical danger but also for his emotional growth. So he becomes more of a mentor figure.
Sirius' character development could involve him coming to terms with his own past traumas while rescuing Harry. He may have to face his fear of Azkaban and the dark magic that he has encountered in his life. As he rescues Harry time and time again, he becomes more confident in his own abilities and his place in the fight against Voldemort. He also starts to see Harry as more than just James' son, but as an important part of the wizarding world's future, which makes him more committed to protecting Harry at all costs.
One example could be a fanfic where Sirius uses his magic and his bond with Harry to heal Harry from a dark curse. Maybe after a battle with Death Eaters, Harry is badly injured, and Sirius, with his extensive knowledge of magic, finds a way to reverse the curse's effects.
There could be an OC who is a descendant of an ancient dark wizarding family. This character might be initially drawn to the dark side because of their family heritage. However, as the story progresses, they start to question their loyalties. Their black OC traits could include having a natural affinity for dark spells and a brooding personality. In fanfiction, they could interact with the main characters in different ways, such as being a rival to Draco Malfoy or an unexpected ally to Hermione in her research on dark magic.
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.
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.
A unique idea could be a fanfic where Sirius Black time - travels. He could go back to his school days and try to change certain events that led to his future troubles. This would be an interesting way to explore his character development in a different timeline.
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.