Well, his relationship with the professors could be affected too. Professor McGonagall might be a bit surprised but ultimately respect his choice as long as it doesn't disrupt the learning environment. Snape, on the other hand, might use it as an excuse to give him a hard time. But with Dumbledore, Dumbledore would probably see it as just another aspect of Harry's growth and individuality. And it could also make Harry more relatable to the younger students who are often trying to find their own identities.
One possible reason could be for a magical disguise. Maybe he needs to blend in with a group where wearing nail polish is a common part of their appearance. Another reason could be as a form of self - expression. Harry has been through a lot and this could be his way of showing a different side of himself, a more rebellious or creative side. It could also be part of a spell or potion gone wrong. For example, he accidentally gets some magical substance on his nails that turns into colorful nail polish.
In this fanfiction scenario, Harry's relationship with Dumbledore could be very interesting. Dumbledore would surely be aware of the significance of Excalibur. He might take Harry under his wing even more, guiding him on how to use the sword's power for good. Harry's relationship with the other Hogwarts students could also change. Some might look up to him even more, while others might fear him because of the great power he now wields.
If Harry is sleepwalking, it might worry his friends. For example, Hermione would probably be very concerned and try to find a way to stop it. This could strengthen their friendship as she devotes time to helping him. Ron, on the other hand, might initially find it funny but then also realize the seriousness. It could also make some of his classmates more curious about him, which could either bring them closer or create some distance depending on how they react to his sleepwalking episodes.
It might make his relationships more interesting. If he reads fanfiction that has unique takes on his friendships, like a story that shows a deeper bond between him and Hermione, he could be more conscious of those relationships in real life and try to strengthen them further.
With his friends, it could initially cause confusion. They are so used to calling him Harry that the new name might be a bit of a shock. But if they understand his reasons, they would likely support him. For example, Hermione might be the first to adapt and help others adjust, using her logical thinking to see the benefits of the name change.
If Harry absorbs the memories of his enemies, it could make his relationships with other characters more complicated. For instance, if he absorbs the memories of Draco Malfoy, he might understand Draco's family pressures better. This could lead to a more complex relationship where Harry has both sympathy and still some animosity towards Draco.
His relationship with Ginny might be affected. Ginny could be very protective of him and worry a great deal. This could lead to some sweet, tender moments between them as she takes care of him during his seizures.
Hermione would probably be very interested in studying how the void - controlling ability works. She'd want to understand the magic behind it, and this could lead to a lot of discussions between her and Harry. Their relationship could become even closer as they explore this new aspect of magic together. Also, his other friends in Dumbledore's Army might look up to him more and be more eager to follow his lead in their fight against the dark forces.
If he transfers, his relationships with his Hogwarts friends would be greatly affected. Hermione and Ron might feel betrayed or worried about him. They might try to convince him to come back. His relationships with his teachers would also change. Some teachers might be sad to see him go, while others might think it's for the best.
His lack of trust would surely strain his friendships. His friends might feel hurt and rejected by his constant suspicion. For example, Hermione, who has always been loyal to him, might be deeply disappointed if Harry doesn't trust her.