One plot idea could be that the house - elf imparts unique magical knowledge to Harry that he doesn't get at Hogwarts. For example, teaching him ancient spells passed down in the house - elf community. Another could be that the house - elf protects Harry from threats in a very different way than Dumbledore or his friends. Maybe the house - elf uses its own brand of magic, which is more instinctive and less rule - bound.
Well, it could be that the house - elf, while raising Harry, accidentally gives him some of its own traits. So Harry becomes extremely loyal to those he cares about, almost in a house - elf - like way. And in terms of his magic, it might be more focused on domestic magic at first. For instance, he can magically clean and organize things with great ease, which is something he learns from the house - elf. This could lead to some interesting situations at Hogwarts when he discovers that most wizards don't have this skill set.
A possible plot idea is that the house - elf raises Harry in a secret location away from the wizarding world's prying eyes. This makes Harry grow up with a different perspective on magic and the world around him. He might develop a closer bond with magical creatures because of the house - elf's influence. Also, the house - elf could have its own reasons for hiding Harry, like protecting a prophecy that only it knows about.
A plot might involve Harry Potter as a house - elf being magically bound to serve Draco Malfoy. This would create a really tense situation as Harry has to resist Draco's cruel orders while still trying to figure out how to break the spell. He could also discover that there are secrets in Malfoy Manor that are related to the Dark Arts and the rise of Voldemort. As he tries to expose these secrets, he uses his wits and the skills he has as Harry Potter, even in his house - elf form, to outsmart the Death Eaters and the Malfoys.
A plot could revolve around a house - elf who gets accidentally mixed up in a dark wizard's plan. Maybe the dark wizard forces the house - elf to steal important magical artifacts from Hogwarts. But the house - elf, having a good heart, tries to find a way to alert the teachers and students without getting caught. Or, there could be a story about a house - elf who befriends a non - magical creature like a Kneazle and they go on an adventure together, exploring the Forbidden Forest and uncovering secrets that are beneficial to the wizarding world.
Well, in some fanfictions, a house elf might gain the power to time - travel through some ancient magic. This could lead to them changing the course of events in the wizarding world, like preventing certain dark wizards from rising to power. Also, there could be a story where a house elf uses their magic to communicate with magical creatures that no one else can, and they team up with these creatures to save Hogwarts from a mysterious threat. And then there's the idea of a house elf's magic being misinterpreted as dark magic, and they have to prove their innocence.
One idea could be that Harry grows up with a very different set of values. House elves are known for their loyalty and hard work. So, Harry might be more in tune with serving others selflessly. For example, he could be more eager to help his classmates with their problems without expecting anything in return.
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 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.
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.