Perhaps a family of powerful but reclusive wizards. They might have seen something special in Harry and decided to adopt him into their bloodline. This family could have their own unique magic and traditions that would influence Harry in different ways compared to the Dursleys.
It could be an old pure - blood family that has been in the background in the original series. Maybe the Blacks who have some complex family dynamics already and taking in Harry could add a whole new layer of drama.
Perhaps a family of magical scholars. They would expose Harry to all kinds of ancient magic texts and theories. This would make Harry not only a better wizard in terms of practical magic but also in understanding the deeper roots of magic. They could be the ones to finally unlock the full potential of Harry's magic, which was stunted by his difficult upbringing at the Dursleys.
The Weasleys could be potential adoptive parents. They already have a big, loving family, and they are very kind - hearted. They could take Harry in and he would fit right in with their rambunctious family dynamic. He would grow up with Ron as his brother in a more official sense, and Molly Weasley would surely dote on him.
The Grangers. Hermione's parents are Muggles, but if they were made aware of the wizarding world early on, they could adopt Harry. He'd have a stable, loving home environment and would also be exposed to Muggle knowledge, which could be really useful in his magical studies. For example, scientific methods could be applied to understanding some aspects of magic better.
One member could be an old, wise wizard who has been living in seclusion for years. He might have a deep knowledge of ancient magic and decides to share it with Harry. Another could be a young witch who is very talented in potions and charms. She could be like an older sister to Harry, helping him with his studies. And there could be a gruff but kind - hearted wizard who is an expert in defensive magic and teaches Harry how to protect himself.
Harry Potter himself can be a common character in such fanfiction. Maybe in these stories, he has an adopted sibling or a new family member through adoption, which changes the dynamics of his relationships. For example, if he has an adopted Muggle - born sister, he might have to protect her more fiercely from the Death Eaters.
A magical tutor for Harry's kids could be an interesting addition. This tutor could have some really unique magical abilities and a mysterious past. Maybe a young witch from a far - off land who brings new spells and cultural elements of magic to the story.
One potential villain could be Voldemort from the Harry Potter world. He might see Harry's new alliance with Erza as a threat and try to destroy it. Also, there could be villains from Erza's world who are jealous of the power that Harry and Erza together possess.
He could become friends with Jimmy Olsen. Jimmy is always curious and open - minded, so he would be likely to be interested in Harry's magical world. Harry could show Jimmy some simple magic tricks, and they could bond over their shared sense of adventure.
One potential new character could be an old hermit - like wizard who has been living in the woods near the manor. He has a deep connection with the land on which the manor stands and can communicate with the spirits of the forest. He could be a source of ancient wisdom for the main characters. Also, a young and adventurous witch who is on a quest to find a lost magical gem that is rumored to be hidden somewhere in the manor. She could bring a new dynamic to the group with her fearless and independent nature. There could also be a magical gardener who takes care of the manor's enchanted gardens and has some secrets of his own.
Obviously, Harry Potter himself would be a main character. Then, there would probably be members of the Potter family, like his adoptive parents. Also, characters like Dumbledore might still play important roles as he often has a hand in Harry's life.