An amputee character can bring a new perspective. They can use magic to create prostheses or aids. For example, they might use a spell to make a magical limb that can do things normal prostheses can't. This adds a unique element to the magical world.
In fanfiction, an amputee can be a part of the story by showing how the wizarding world is inclusive or not. They could face discrimination from some pure - blood families who think a disabled wizard is weak. But then they can prove them wrong by their skills in magic, like in dueling or potion - making. It also allows for exploring themes of acceptance and friendship. For instance, Harry and his friends could befriend the amputee character and help them overcome difficulties. This would show the positive side of the Hogwarts community.
Well, in fanfiction, Merlin might be reincarnated in the Harry Potter era. He could retain some of his past memories and powers. As a character, he would bring a different style of magic, one that is more in tune with nature and less structured compared to what the wizards in Harry's world are used to. His arrival could cause a stir among the magical community, with some seeing him as a savior and others as a threat, all while having a special connection with Harry, perhaps as a mentor or a long - lost relative in the magical sense.
The Kitsune can also be a mysterious figure in the Harry Potter universe of fanfictions. It could be a being that has been around for a long time, but has stayed hidden until Harry's time. It might have its own motives for getting involved with Harry, such as a prophecy that ties its fate to Harry's fight against Voldemort.
In fanfiction, umbramancy can fit in by being a long - lost or forgotten magic. It could be something that was once used by ancient wizards but lost over time. For example, it might be rediscovered in the Forbidden Forest by a curious student.
Nyarlathotep could be a new, powerful and malevolent force that disrupts the balance of the Harry Potter universe. He might be an entity from a different dimension that finds its way into the wizarding world, causing chaos.
Cortana might be seen as a powerful magical tool in the Harry Potter fanfiction world. Some might write that she has the power to enhance a wizard's magic. Imagine a wizard using Cortana to boost the power of their spells. She could also be used to store magical knowledge, like a magical hard drive, and wizards could access this knowledge to learn new spells or techniques.
Mithril might be incorporated into the fanfiction as a material that has a special connection to certain magical creatures. Maybe unicorns are attracted to Mithril, and a plot could revolve around a group of students trying to use Mithril to lure a unicorn to safety from a poacher. Along the way, they learn more about the magical properties of Mithril and how it interacts with the magic of the unicorn, which in turn could have implications for other areas of magic within the 'Harry Potter' universe.
Freerunning can fit into the Harry Potter universe by adding a new dimension to movement. For example, it can be used for escaping from dark wizards in the narrow alleys of Diagon Alley or Hogsmeade. The characters can use their parkour skills to quickly jump over obstacles and get to safety.
Illumi can fit in as an outsider with unique skills. His combat and stealth abilities are not like anything in the wizarding world, so he could be a wildcard. For instance, in some fanfictions, he might be seen as a new kind of threat or an unexpected ally to the Order of the Phoenix.
Astoria Greengrass often serves as a bridge between different storylines. She can be used to explore the post - war Slytherin perspective. For example, in some fanfictions, she helps to heal the rift between Slytherin and the other houses.
The Sharingan can fit by enhancing a character's perception. In fanfiction, it could make a wizard like Harry more aware of his surroundings during duels. He could see the flow of magic more clearly, similar to how in the Naruto universe, Sharingan users can see chakra.