Given the nature of Nightmare Moon's domain, Harry's magic might become more defensive and protective in a different way. He could develop shields and barriers that are not just physical but also mental and emotional, as he faces new threats that are not like the Death Eaters or Voldemort. His magic would evolve to fit the unique challenges of his new life with Nightmare Moon.
Harry could also find that his magic is more attuned to the emotions and dreams of those around him, just like Nightmare Moon is. This could give him new abilities to manipulate or interact with the subconscious of others. He might have to learn to control this new aspect of his magic, which could be very different from controlling his wand - based magic.
Harry might become more isolated from his peers at Hogwarts. Since he was raised by a lich, he may have different values and a darker sense of humor. His views on life and death could be more complex compared to other students.
His magic might develop in a more practical and combat - oriented way. Instead of just using magic for spells in a classroom or dueling, he could learn to use it in the heat of battle at sea. For example, he might learn to quickly cast protective spells while on a ship during an enemy attack.
She might be more empathetic. Since being adopted, she would have a different understanding of family and belonging. This could make her more open - minded towards others, like the outcasts in the wizarding world. For example, she might befriend the werewolves more easily.
Harry's character would likely be a mix of confusion and determination. He'd be confused by Voldemort's teachings which go against his natural inclination towards good. But his determination to find his true self would remain. He might develop a sort of duality, acting one way around Voldemort and his followers, but secretly being someone else.
His personality would likely be a blend of his natural Gryffindor traits and the influence of the Malfoy family. He might become more guarded and calculating at times, due to the Malfoy's sly nature. But his underlying sense of justice and loyalty would still shine through. For example, he might be more hesitant to trust people initially compared to in the original story.
Harry's character would likely become more aware of different cultures. Growing up among the Cullens, he'd be exposed to vampire culture. This would make him more open - minded. He might also become more cautious, as vampires have different threats compared to the wizarding world.
He could develop new interests and skills. Since he's in a different family environment, he might be exposed to different hobbies or magical studies. For instance, if Dean's family has a tradition of potion - making in a unique way, Harry could pick up on that and become quite proficient, which would also boost his confidence.
His character would become more worldly. Since the Delacours are from France, Harry would be exposed to different values and ways of life. This could make him more open - minded. For example, he might be less rigid in his views on magic compared to when he was only in the British wizarding world.
His character would develop in multiple ways. Firstly, he'd become more resourceful. The Winchesters often find themselves in tight spots, and Harry would have to learn to use whatever he has at hand, including his magic, to get out of trouble. Emotionally, he might become more guarded as he realizes the harshness of the world they live in. But at the same time, he could also develop a stronger sense of loyalty towards the Winchesters, seeing them as his new family.
Harry's character would likely become more stoic. Byakuya's influence would make him more reserved in showing emotions. He might also become more strategic in his thinking, as Byakuya is known for his calculated moves.