In some fanfictions, Harry might use powerful magic he's learned secretly. For example, he could discover a new spell that can break the Azkaban's defenses. He then sneaks into Azkaban, locates Sirius, and uses this spell to free him from his cell. Maybe he also has to fight off some Dementors on the way out.
There are fanfictions where Harry uses his connection with his parents. He might have a vision or some sort of spiritual guidance from them. This leads him to find a hidden passage into Azkaban. Once inside, he uses his Patronus, which has grown extremely powerful, to ward off the Dementors. Then he locates Sirius and uses a combination of magic and his own courage to break Sirius free from whatever is holding him in his cell and they escape together.
Well, in certain fanfiction scenarios, Harry might enlist the help of his friends. They could all work together to create a diversion outside Azkaban. While the guards are distracted, Harry, who has somehow managed to get a hold of the keys or a way to unlock cells, enters and rescues Sirius. It could involve Hermione using her intelligence to figure out the prison's layout and Ron being brave in the face of danger during the diversion.
In most fanfictions, Harry was around 13 years old when Sirius broke out of Azkaban.
It varies in different fanfictions. Some have Harry at 12, while others might depict him as 14 when this event occurs. It depends on the author's imagination and the story's plot.
One major challenge is the Dementors. They are extremely dangerous and can suck out a person's soul. Harry has to find a way to either avoid them or defeat them. Another challenge could be the security measures in Azkaban. There might be magical locks, guards, and other barriers that he needs to overcome.
Yes, it's possible. Sirius is a popular character in the Harry Potter series, and many fans like to imagine him in different scenarios in fanfiction. He has a complex personality and a lot of untold stories, so fanfiction about him in the context of 'Prisoner of Azkaban' can be very interesting.
One interesting plot point could be how Harry devises the plan to break Sirius out. Maybe he uses his invisibility cloak and some clever spells. Another could be the reactions of the other characters when they find out, like Hermione's concerns about the legality and consequences.
Obviously, Harry and Sirius are the main characters. Harry is the one trying to break Sirius out, and Sirius is the one being broken out.
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.
One great fanfiction could be 'Sirius's Redemption'. In this fic, Sirius, after escaping from Azkaban, tries to reintegrate into the wizarding world while dealing with his past traumas. It delves deep into his relationships with Harry and his old friends. The author does an amazing job of portraying Sirius's struggle with his sanity after years in that dark prison. Another interesting one is 'Sirius: A New Beginning'. It focuses on Sirius starting a new life outside of the shadow of Azkaban, exploring new magic and forming new alliances. It's a really engaging read if you like seeing the character grow in different directions.
In many fanfictions about Sirius Black in Prisoner of Azkaban, he is often given a chance for a new adventure. Writers might imagine him escaping Azkaban in more elaborate ways, or having different interactions with Harry Potter and his friends. For example, some fanfictions have him forming a secret alliance with other prisoners to break out together.
One could also write a fanfiction about Sirius Black's impact on Hogwarts during the events of Prisoner of Azkaban. For instance, his presence, even though he's on the run, could have a big influence on the students. Some students might start to question the Ministry of Magic's actions, and Sirius could inspire them to fight for justice.