Well, it could be that when Harry is released from Azkaban, he discovers new magical powers or abilities that he developed during his time there. He might then use these powers to fight against the dark forces that once put him in Azkaban. And he would surely have to deal with the psychological trauma of being in that awful place as he tries to move forward in his life.
It could be Hermione. She's always been smart and resourceful, and she might have found evidence to prove Harry's innocence and get him released.
One possibility is that Dumbledore discovers new evidence that clears Harry's name. Maybe there was a misused spell by the Ministry that made it seem like Harry was guilty. Dumbledore then uses his influence and magic to break Harry out of Azkaban and they begin to expose the real culprits behind the false accusations.
One possible scenario could be that new evidence is found to prove Harry's innocence. Maybe a powerful magical object reveals the truth about what really happened, leading to his release.
Obviously, Harry himself is a key character. His own strength, both physical and mental, could play a role in his release. For instance, he might have developed some new magical abilities during his time in Azkaban that help him break free.
Obviously, Harry Potter himself is a key character as the story is about his release from Azkaban. Dumbledore is likely to be important too. He has the power and influence within the wizarding world to potentially free Harry. His wisdom and knowledge of the situation would play a big role.
One possible plot could be that Harry was wrongly imprisoned. Once released, he'd be on a quest to find out who framed him. He might start by gathering his old friends like Hermione and Ron. They would then dig into the dark secrets of the wizarding world that led to his false incarceration.
He might use the invisibility cloak. Harry could sneak into Azkaban unnoticed and then use magic to break Draco out of his cell. The cloak has served him well in the past, and it would be a simple yet effective way to get past the guards.
There could be some new characters introduced in the fanfic. Maybe a powerful wizard from a far - off land who has heard of Harry's plight and decides to help. Or perhaps a group of outcasts in the wizarding world who see Harry as a symbol of their own struggle against the unjust system and come to his aid.
One possible motivation could be guilt. Snape has always had a complicated relationship with Harry. Maybe he feels guilty for not preventing Harry from being wrongly accused and sent to Azkaban. So, he decides to make it right by rescuing him.
One possible fanfiction could involve Harry finding out that Draco was wrongly imprisoned in Azkaban. Harry might use his influence and his skills as an Auror to dig deeper into Draco's case. He could discover evidence that clears Draco's name, like finding out that Draco was framed by some dark wizards who wanted to get rid of the Malfoy family's influence. Then, Harry would have to fight against the bureaucratic system of the Ministry of Magic to get Draco released.