One interesting aspect could be the unique magical creatures that might be found there. In many fanfictions, authors create new species specific to the Hidden Island. For example, there could be flying serpents with the ability to change colors according to their mood. Another aspect is the potential for undiscovered magic. The island might hold ancient spells or magical artifacts that are long forgotten in the wizarding world. This could attract many adventurers and researchers in the fanfiction. Also, the social structure on the Hidden Island could be different from the mainstream wizarding society. It might have its own set of rules and traditions that make it a fascinating place to explore in the context of the Harry Potter universe.
In some fanfictions, it could be descendants of minor characters from the original Harry Potter series. For instance, the grandson of Hagrid might be drawn to the Hidden Island to continue Hagrid's love for magical creatures. He could be one of the main characters, trying to protect the unique and endangered species on the island. Also, there might be a group of students from Hogwarts who get lost during a field trip and end up on the Hidden Island. Among them, a character like Hermione - like girl, intelligent and resourceful, would take the lead in trying to figure out how to get back and in the process, uncover the island's secrets.
A hidden secret might also lie in the relationships between different wizarding families. There could be long - held grudges or alliances that are not fully explored in the official books. Fanfiction can unearth these secrets, like a feud between two families that has been going on for centuries but has been kept quiet from the general wizarding public.
He might have discovered the island during one of his adventures and claimed it as his own. Since there was no one else on the island at the time, and he was the first to set foot on it and recognize its potential, he decided to make it his property.
Perhaps he uses the island as a secret training ground. He could practice advanced spells away from the prying eyes of Hogwarts faculty and students. Harry might also build his own magical fortress on the island for protection and privacy.
Well, one hidden secret could be the true nature of some magical creatures. In fanfiction, we might find that thestrals have a deeper connection to the afterlife in the wizarding world than we thought. Maybe they are not just seen by those who have witnessed death, but they also play a role in guiding lost souls.
The 'hidden legacy' in Harry Potter fanfiction might be a variety of things. It could be a dormant magical gift that awakens under certain circumstances. For instance, a character might have a 'hidden legacy' of being able to communicate with ghosts in a way no one else can, because their great - great - grandmother was a powerful seer who had a special connection to the spirit realm. It could also be a physical object or a piece of knowledge that has been hidden away for centuries and is now emerging through the character's story.
There could be some of the house - elves that Harry has freed. They might choose to live on the island, using their magic to help with various tasks such as farming magical plants or taking care of the island's infrastructure. Also, some of the students from Hogwarts who were inspired by Harry could be there. They might be learning new forms of magic that are specific to the island or studying the unique magical ecosystem there.
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.
I'm not sure specifically as there could be many different takes in such a fanfiction. It might be about Harry Potter discovering or owning an island, perhaps with magical elements on it, like hidden magical creatures or ancient spells.