In some fanfiction, a possible plot could involve Harry using his time in the orphanage to study magic on his own. He might find some old, tattered magic books in the orphanage attic that were left behind by a former wizard who lived there secretly. The orphanage could also be a place where dark wizards are secretly observing Harry, waiting for the right moment to use him for their own evil purposes. Harry would then have to use his wits and the little magic he knows to outsmart them. Another aspect could be that the orphans' collective emotions create a unique magical force that Harry has to learn to control and use for good.
Well, a cool plot could be that Harry forms a strong bond with an old caretaker at the orphanage who turns out to have a mysterious past in the wizarding world. This caretaker could be the one to introduce Harry to some basic magic concepts before he even gets his Hogwarts letter. Also, there could be a rival orphan who is jealous of Harry's emerging magic and tries to sabotage him. And what if the orphanage is a gateway to a parallel wizarding world that has been cut off from the main one?
One plot idea could be that Harry discovers a hidden magic within the orphanage itself. Maybe there's a secret room that holds ancient spells or a connection to a long - forgotten wizarding family. Another idea is that the other orphans start to show signs of magic too, and Harry has to figure out how to protect them from the wrong kind of attention. Or perhaps the orphanage is under a curse, and Harry's presence there is the key to breaking it.
In the fanfiction, it could be interesting if Harry uses his magic to protect the other orphans from bullies. He might not fully understand his powers yet, but his instincts kick in. And then when he finally gets his Hogwarts letter, the other orphans are both sad to see him go but also excited for him, and he has to figure out how to leave the only home he's known while also being eager to enter the wizarding world.
One interesting plot idea could be that Snape, in raising Harry, teaches him advanced potions from a very young age. Harry becomes a prodigy in potions, much to the surprise of the other Hogwarts students. Another idea is that Snape's strict but fair upbringing makes Harry more reserved and less impulsive, which changes the way he interacts with his friends. He might be more cautious and calculating in his actions, especially when dealing with enemies like Voldemort.
One plot idea could be that Shield trains Harry in combat and espionage skills from a young age. This makes him a more physically and tactically adept wizard compared to the original story. He might use his new skills to uncover dark secrets within the wizarding world earlier.
One plot idea could be that Harry's grandparents are very strict about magic, so he has to secretly practice. Another could be that they are part of a secret wizarding society that has been in hiding, and Harry discovers their secrets. Or perhaps they have a special connection to Voldemort's past that Harry uncovers.
One idea could be that the orphanage is a hidden place for magical orphans with special powers. The orphans form a secret society within the orphanage to protect themselves from dark wizards who want to use their powers. They learn magic on their own, using old books they find in the attic of the orphanage.
One idea could be that Harry uses his fame and wealth to completely renovate the orphanage. He could introduce magic in a subtle way, like using magic to make the food taste better or the beds more comfortable for the kids. Another plot could involve Harry finding out that some of the orphans have latent magical abilities and he decides to mentor them privately before they are old enough to go to Hogwarts.
One interesting plot could be how Harry's magical abilities are perceived in a world of nations. Maybe he uses his magic to solve international disputes. Another idea is that different nations try to influence his upbringing, each adding their own cultural and magical elements to his training.
One idea could be that Harry grows up with cat - like reflexes and stealth. He might be able to move around Hogwarts unnoticed more easily, like a cat prowling in the shadows.
One idea could be Harry being raised by the Weasleys from a very young age. He'd grow up with their large family dynamic, learning magic in a more chaotic but loving environment. It might change his personality a bit, making him more outgoing and confident earlier. Another plot could be him being raised by Remus Lupin. Lupin would instill in him a deep understanding of the dark arts in a more academic way, and also teach him about acceptance of his own lycanthropy - like condition if he were to inherit it. And a third idea is Harry being raised by the centaurs in the Forbidden Forest. He'd learn their unique brand of magic, which is more in tune with nature, and have a different perspective on the wizarding world and its relationship with the natural world.
Well, he could be raised in a small, idyllic French village full of magic. The local wizards there might be more in tune with nature magic. So, Harry grows up learning how to communicate with magical creatures in the French forests in a way that's different from what he'd learn in Britain. Maybe there's a mystery about his parents in the French wizarding world too. Like, they were involved in some secret mission in France before they died, and as he grows up, he starts to uncover clues about it.