Harry could face isolation. Other wizards might be afraid of him because of the Horcrux inside him. His friends might also be in danger just by being close to him. Moreover, Harry's own mental state could be affected. He might feel like a burden or an outcast, and struggle with the knowledge that he has a part of Voldemort's soul in him.
One possible consequence is that Harry becomes an even bigger target for Voldemort. Since a Horcrux is important to Voldemort's immortality, he'd be more determined to get to Harry. Also, Harry might start to experience some strange effects on his soul or magic due to being a Horcrux.
Well, Sirius is a very protective character. When he discovers that Harry is a Horcrux in the fanfic, he could initially be in denial. But once he accepts it, he'd likely start looking for ways to either protect Harry from Voldemort or find a way to remove the Horcrux part from Harry. He might also feel angry that Harry has been put in such a dangerous situation.
Sirius might be shocked. He'd probably feel a mix of horror and protectiveness. He'd be horrified that Voldemort has used Harry in such a way and would be even more determined to keep Harry safe from Voldemort's clutches.
One implication is that Harry's life is in even more danger. Voldemort might be more determined to keep him alive until he can fully use Harry for his own evil purposes.
He could lose his friends. In the original story, his friends stand for good and oppose black magic. If Harry starts learning it, they might turn their backs on him. Also, he could be ostracized by the wizarding community. The wizarding world has a clear stance against black magic, and Harry would become an outcast.
Well, if Sirius Black hates Harry Potter fanfiction, it could lead to a divide among fans. Some fans might respect his view and be more critical of fanfiction themselves, while others might disregard his feelings. Also, it could potentially limit the creativity within the fan community as people might be afraid to create content that could be seen as disrespectful to Sirius Black's character.
On the other hand, not competing might lead him to find alternative paths. He could start his own non - competitive projects or groups, which could have a big impact on the fanfic's community in a different way. For example, he could form a study group for magic that focuses on sharing knowledge rather than competing for grades or status.
There could be unforeseen magical consequences. Time - traveling is a tricky business in the wizarding world. By changing Sirius' fate, Harry might accidentally create new problems. For example, the balance of magic in certain areas could be disrupted. There might also be changes to the Hogwarts' community. Students and teachers who were affected by Sirius' situation in the original timeline might act differently.
Well, it could have all sorts of consequences. Maybe the ritual is meant to unlock some hidden power within Harry. If it goes wrong, it might put Harry in danger, like attracting dark forces. Or perhaps it's a ritual to communicate with the past, and if not done properly, it could mess with time and space.
One consequence could be a split in the friendship group. If Harry hates Ginny, Ron, being Ginny's brother, would be in a difficult position. It could lead to a divide between Harry and Ron as well.
Well, in the 'ginny cheats on harry fanfic', a consequence might be that Ginny loses the trust of those around her. Harry might become more guarded in future relationships. Their families would also be affected. For example, the Weasley family might have to deal with the fallout and try to understand why Ginny did such a thing. And Ginny herself could end up feeling very guilty and regretful.