Hermione would probably be involved. She could help Harry research about the island, like its history and any magical properties it might have.
Obviously, Harry Potter himself is the most important. Then there could be some old villagers who know all the secrets of the village and guide Harry.
Hermione could be one. She might follow Harry to the island to help him out. Another could be Ron, his loyal friend. Or it could be some new characters created specifically for this fanfiction, like a wise old wizard who has been living on the island for centuries.
Maybe some of the Hogwarts professors could be involved. For example, Professor McGonagall could be concerned about Harry's new situation and offer her guidance. There could also be some descendants of previous island owners or caretakers who have their own interests in the island. They could either be friends or foes to Harry, adding more complexity to the story. Additionally, some magical creatures native to the island could be almost like characters themselves, interacting with Harry in unique ways.
Hermione could be important. She might be the one who encourages Harry to drop his mask, or she could be the first to notice the change when he does. Another could be Ron, as Harry's best friend, his reaction to Harry dropping his mask would be significant.
Hermione could be important. She might help Harry in his journey as a mage, using her intelligence to research and understand new magical concepts that Harry discovers. Ron could also be there, providing his loyalty and friendship, perhaps even joining Harry in some of his mage - related adventures. And then there could be a new character, a powerful mage who becomes Harry's mentor and teaches him the deeper secrets of magic.
Hermione would probably be one of the main characters. She's smart and resourceful, so she could help Harry with the administrative side of running the orphanage, like handling finances and paperwork. Ron might also be involved, perhaps teaching the orphans some practical magic skills. And of course, there could be some of the orphans themselves as main characters, like a young girl with a special magical ability that Harry discovers.
One possible plot could be that Harry discovers the island is a magical place filled with ancient spells and potions. He might use it as a sanctuary away from the wizarding world's chaos, perhaps to study magic in peace and develop new spells.
In this fanfiction, the island could be a place where Harry's family had some sort of connection in the past. There could be a hidden family legacy there. Harry might find old family artifacts, and through exploring the island, he uncovers more about his family's history and how it ties into the wizarding world as a whole.
Besides Harry, there could be a character who is a descendant of an ancient elemental magic family. This character might initially be a rival to Harry in mastering the magic but later becomes an ally. Also, Dumbledore could play an important role. He might be secretly guiding Harry in his journey of learning elemental magic, using his own deep knowledge of the wizarding world's secrets.
Ron might be there too. He could use his skills in handling magical creatures to populate the island with friendly ones. And he could also help with fishing in the surrounding waters using magic, providing food for those on the island.