Well, in many Harry Potter AU fanfictions, travel to an alternate universe can happen due to a disruption in time. If a time - turner is misused or there's a major magical event that messes with the time - space continuum, it can lead to an AU. Also, some fanfictions depict that a character's strong emotions and desires can trigger a journey to an AU. Say a character has a deep longing to see how things could have been different, and their magic responds by sending them to an AU. It's all very creative and varies from one fanfiction to another.
Well, in AU Harry Potter fanfiction related to traveling, you might encounter unique magical creatures that don't exist in the original universe. These could range from friendly, helpful beasts to terrifying and dangerous ones. The social structure of the wizarding world could also be different. There could be new political systems or different ways that pure - bloods, half - bloods, and Muggle - borns interact. And don't forget about the magic items. There could be new, powerful artifacts that drive the story forward, or existing ones with different properties or backstories.
He may be confused at first. Fanfics can be very different from his real experiences. He might wonder why people write such things about him and his world.
Well, Harry Potter is a rather humble character. He might initially feel a bit embarrassed to see himself as the center of so many fictional stories created by fans. If the fanfic portrays him as a hero in new adventures, he would probably be honored. However, if it misrepresents his friends or the values he holds dear, he could be a bit indignant. He would likely approach it with an open mind but also with a sense of protectiveness towards his own story and those he loves.
A great antagonist could be a corrupted teacher. For instance, a teacher who is secretly working for Voldemort but has been hiding in plain sight at Hogwarts for years. They could manipulate the Triwizard Tournament to their own ends, causing all sorts of trouble for Harry and his friends.
As time goes on, Harry could start to explore what it means to 'please' Sirius. He might recall their past relationship, the things Sirius likes and dislikes, and try to use that knowledge to his advantage. He may also feel a sense of loyalty towards Sirius that, despite the odd circumstances, makes him more accepting of the situation. For example, he might remember Sirius' love for adventure and try to engage in some magical adventures with him in a way that 'pleases' him.
There's a chance he'd be inspired. The stories of the Naruto characters' determination and growth in the fanfiction could stir something in him. He might think about his own journey as a wizard and how he can further develop his skills and character, taking cues from the Naruto characters' tenacity.
A great plot twist could be that the Dementors are being controlled by someone other than the Ministry. They start attacking students more frequently and specifically target Harry because they are being used to find something that Harry unknowingly has. This would make the already dangerous situation in the third year even more intense.