His sense of responsibility would grow exponentially. Since he's the only one left, he feels it's his duty to preserve the magic world. He could start to develop new magical abilities as he has all the resources and time to experiment. He might also struggle with his identity, as so much of who he was was tied to his relationships with others. Now that they're gone, he has to redefine himself and what it means to be Harry Potter in this new, lonely world.
Harry might become more introspective. He has all this time alone to think about his past, his family, and the things he's been through. He could also become a bit paranoid, always on the lookout for threats since he has no one to back him up. He might start seeing the magic world in a different light, now that he's the only one there to experience it.
His character would likely become more self - reliant. Without his friends and mentors around, he'd have to depend solely on himself. For example, he'd need to make all his own decisions without Hermione's advice or Ron's support.
One possible plotline could be that Harry Potter wakes up alone and at first he's in shock. He might then start exploring the empty world. He could visit Hogwarts which is now deserted. He might find himself reminiscing about his friends and the good times they had. He would have to figure out how to survive on his own, like growing his own food in the Hogwarts gardens which were once tended by the house - elves. He may also stumble upon some magic that was hidden when the world was full of people, and this new discovery could either give him hope of bringing others back or make him more resigned to his lonely existence.
If Harry wakes up with Fleur, it could be a bit of a shock for both of them. But then, they might find that they are drawn to each other's personalities. Fleur's elegance and confidence might attract Harry, and Harry's courage and kindness could win Fleur over. Their relationship could develop as they face challenges together. For example, they might have to fight off some dark wizards who are after a powerful magical artifact. Through these experiences, their bond could strengthen into a deep and loving relationship.
He would likely be more confident. Growing up with his grandparents, who presumably love and support him, he wouldn't have the self - doubt that came from living with the Dursleys. He would be more self - assured in his magical abilities from the start.
In such a fanfic, Harry would become more experimental. He would start to combine his traditional spell - casting with the new abilities of the sword - wand. For example, he might try to cast spells while swinging the sword, creating unique magical attacks. This would make him a more unpredictable and formidable opponent. His character would also grow in terms of his relationship with magic itself. He would no longer take his wand for granted and would have a deeper understanding of the fluid nature of magic, which could lead to him being more open - minded about different forms of magic and magical artifacts in the future.
He would become more adaptable. Middle - earth is so different from the wizarding world, so he'd have to learn new ways. His character might become more in tune with nature like the elves in Middle - earth.
His character could become very conflicted. On one hand, he is being taught by villains, so he might be cynical and distrustful. But on the other hand, he might have an innate goodness that fights against what he's being taught. He could develop a unique set of skills, like the ability to deceive and manipulate from the villains, but also a sense of honor that comes from within.
It would show Harry as a more intellectual and curious character. His love for math could lead him to explore areas of magic that others haven't. For instance, he might use math to predict the movements of magical creatures, making him seem more of a wizard - scientist.
His character might become more assertive and self - reliant. At Durmstrang, which has a different culture than Hogwarts, Harry would have to stand up for himself more often. He'd also learn different magical techniques, which could make him more versatile in his magic use.
He'd probably be more refined in his manners, as French culture often emphasizes politeness and etiquette. His accent would be different, of course. And he might be more confident in expressing his emotions, as the French are generally more open about feelings. Also, his view of magic might be more influenced by French magical aesthetics, which could be more about elegance and style.
She might be an old friend of Harry's from his childhood in the Muggle world that he didn't know was a witch. She had been suppressing her magic for a long time and fainted when it finally burst out uncontrollably. Harry wakes her up and helps her understand and control her new - found powers.