This immunity can also protect Harry from potential manipulation. In the wizarding world, love potions can be misused. By being immune, he doesn't have to worry about someone using a love potion to make him do things against his will in a relationship. It gives him more control and allows him to build relationships based on mutual respect and true feelings.
Well, it could make his relationships more genuine. Since he's immune to love potions, any romantic feelings towards him are likely to be real and not magically induced. This means that the people who fall for him truly like him for who he is, not because of a potion's false allure.
In the fanfiction world, it could be a gift from a powerful being. There are many powerful wizards or magical creatures in the Harry Potter universe. Maybe one of them, seeing Harry's importance or just out of kindness, bestowed this immunity upon him to protect him from the potential chaos that love potions can cause.
Well, it could change the way other characters interact with Harry. For example, if there are Veela characters in the story, they might be frustrated or intrigued by his immunity. This could lead to new alliances or rivalries. Maybe it also makes Harry a bit of an outlier in magical society, as the Veela allure is usually quite powerful and his immunity sets him apart.
His potion - making skills might make him more respected by his classmates. They could come to him for help with their potions homework or for advice on how to improve their own skills.
In some fanfictions, Harry might develop immunity to mind magic through a powerful magical artifact. For example, he could find an ancient amulet that shields his mind from external mental intrusions.
He might be seen as a threat by some dark wizards. Since they can't use mind magic on him, they fear his potential to disrupt their plans. For example, Voldemort might target him more directly as he can't manipulate Harry's mind.
If Harry changes his look to seem more intimidating, it might make some of his enemies more cautious around him. For example, if he has a more severe look with a long beard and a scowl, the Death Eaters might think twice before attacking him. As for his friends, they might be a bit taken aback at first but would quickly accept the new look.
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.
Well, his potion skills might make Snape a bit more lenient towards him. Since Snape is the potions master, he might respect Harry's talent more, reducing the usual animosity. With his friends, Harry could share potion-making tips, strengthening their bond. For example, he could help Hermione with some tricky potion recipes, and she'd be impressed by his newfound skills.
His relationship with Ginny could also be affected. Ginny is a passionate Quidditch player herself. She might initially be sad that Harry is leaving the sport. But if she truly loves Harry, she will come to understand his reasons and support him. And Harry might feel guilty for disappointing Ginny, which could add some tension to their relationship at first.