In certain 'Harry Potter Reborn Fanfic' stories, Harry is reborn with enhanced magical abilities. He may discover new spells or magical techniques that were lost over time. This allows him to stand out even more than he did in the original series. These fanfics often focus on how he uses these new powers to combat the dark forces in the wizarding world in a more efficient way.
Well, you might find a plot where you're reborn into the Harry Potter fanfic as a muggle - born who has a unique ability. For example, you could have the power to communicate with magical creatures in a way no one else can. This would lead to all sorts of adventures, like helping Hagrid with some of his more dangerous or difficult creatures. Or perhaps you're reborn as a pure - blood who wants to break free from the traditional pure - blood elitism and fight for equality in the wizarding world. You could also be reborn as a character who discovers a hidden part of Hogwarts that no one else knows about and uncovers its secrets.
There are 'Harry Potter fanfic fanfic' that focus on time - travel scenarios. Imagine if a character from the later books travels back in time to the first year at Hogwarts. This can create a lot of interesting plot twists as they try to change or preserve the original story line. Also, some fanfic fanfic might center around magical creatures in a way that wasn't fully explored in the original books, like the life of a hippogriff in more detail.
A really interesting plot could be that the reborn character is actually a huge Harry Potter fan in their previous life, so they know all the secrets and prophecies. They use this knowledge to their advantage. For instance, they might be able to figure out how to defeat Voldemort more quickly by using a combination of things they remember from the books and their own new ideas. They could also change the relationships between characters. Instead of Harry and Hermione just being friends, the reborn character could nudge them towards a romantic relationship earlier on, which would then have a ripple effect on the whole story.
Some 'Harry Potter and Lily Potter fanfic' might focus on alternate universes. In one such story, Lily could have survived Voldemort's attack. She would then have to raise Harry in a world that is still recovering from the Dark Lord's first rise. This would change a lot of the dynamics in the story. Harry would grow up with his mother's love and protection, and Lily would have to deal with the knowledge that Voldemort could return at any time.
One interesting plot twist could be that Harry, now reborn as a Malfoy, uses his knowledge of the future to prevent certain dark events in the wizarding world that the original Malfoys were involved in. He might try to change the family's loyalty from Voldemort to the side of good.
One idea could be that the main character from Reborn is reborn into the Harry Potter world as a wizard with his unique skills. He could use his combat abilities from Reborn to face the dark wizards in the wizarding world. Another could be that a character from Harry Potter gets reborn in the Reborn universe and has to adapt to the different rules and powers there.
I'm not really in favor of the 'slaves' concept in fanfic as it can be a bit disturbing and against the positive spirit of the original 'Harry Potter' series. However, some fanfics might explore power dynamics in a more metaphorical way. But overall, the official 'Harry Potter' works focus on friendship, courage and magic, not slavery themes.
One interesting 'Harry Potter breed fanfic' story could be about the breeding of Hippogriffs in a more domesticated setting. Maybe it explores how wizards are trying to train them for various tasks like mail delivery in a different way than using owls.
One interesting 'Harry Potter Siren Fanfic' could be about a siren who uses her charm to influence the events at Hogwarts in a subtle way. Maybe she befriends Harry and tries to guide him through some challenges using her siren - like powers, which are different from magic but still effective.
There might be a fanfic where a MACUSA auror teams up with a Hogwarts student. They could be working together to stop a dark wizard who is causing chaos in both the American and British wizarding worlds. The story could explore how their different magical educations and approaches to magic come into play.