In the fanfiction, Harry might have some magical encounters during his investigation. He could have a vision of Sirius's past, showing what really happened on the night of the crime. This vision could be triggered by a powerful magical object that he discovers. With this newfound knowledge, he then sets out to expose the truth and clear Sirius's name once and for all.
Harry could also team up with Hermione and Ron. Hermione would use her extensive research skills to dig into the Ministry's files on Sirius. They might find that there were some irregularities in the trial process. For example, crucial evidence was withheld or fabricated. Ron, on the other hand, could use his family's connections within the wizarding world to gather more information about the people who were involved in the case against Sirius.
Another aspect of this fanfiction could be that Harry uses his Parseltongue ability to communicate with the snakes in Azkaban (if there are any). The snakes might have some information about Sirius since they can sense the emotions and secrets of the prisoners. Through this unique method, Harry gets closer to proving Sirius's innocence.
One interesting plot is when Harry discovers a hidden prophecy about Sirius Black that leads him on a dangerous quest to uncover the truth. Another is when Harry suspects Sirius of being involved in a dark magic plot and has to spy on him secretly. There are also stories where Harry and Sirius team up to investigate an ancient mystery within the wizarding world that has been long forgotten.
You can start by looking on popular fanfiction websites like Fanfiction.net or Archive of Our Own (AO3). On Fanfiction.net, use the search bar and type in 'Harry investigates Sirius Black'. Sort the results by popularity or rating to find the well - liked ones. AO3 also has a great search function. You might also want to check out some Harry Potter - focused fan communities on platforms like Reddit, where fans often recommend their favorite fanfictions.
Well, Sirius would surely focus on making Harry as self - sufficient as possible given his blindness. He might train Harry to use his wand in a more instinctive way, relying on muscle memory and his other senses. Maybe Harry would learn to sense the presence of dark wizards through vibrations in the air or changes in temperature that normal wizards might not notice.
In a 'Harry and Sirius join Voldemort' fanfiction, it might start with Voldemort making a very tempting offer. For Harry, it could be something related to saving his friends or family. Sirius might be lured by the idea of protecting Harry in a different way. However, once they join, they would face a moral dilemma. They would have to pretend to be on Voldemort's side while still holding onto their own values. And there would be a lot of internal conflict as they see the evil deeds happening around them.
In this fanfiction, Sirius might find a new sense of family and belonging with the Potters. He could help James Potter in protecting Lily and Harry, adding an extra layer of defense. Maybe he'd also share some of his unique magical knowledge and skills with them.
In such a fanfiction, they could be on a quest and the car could be a magical vehicle that malfunctions. Hermione might use her intelligence to try and fix it while Sirius uses his experience to protect them from any threats that come their way during this situation.
Well, Sirius might see some of his own qualities in Harry's boyfriend. Maybe the boyfriend is brave like Sirius was, and Sirius would then start to warm up to him. He could share some of his old Hogwarts stories with the boyfriend, which would help the boyfriend understand Harry's world better.
In fanfiction, when Harry and Ginny meet Sirius, Sirius might offer them some sage advice on dealing with the dark forces. He could share his experiences about fighting Voldemort and his Death Eaters. Maybe he would see the potential in Ginny and encourage her to further develop her magical abilities, as he has always been supportive of Harry.
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.