His magical abilities would be used in a different context. Instead of using magic mainly for school competitions or fighting Voldemort's Death Eaters, he'd be using it to combat vampires, ghouls, and other supernatural beings that Hellsing faces. His view of good and evil might also change. In the wizarding world, there were clear lines between good wizards and bad wizards. But in Hellsing, the lines between what is acceptable in the fight against evil can be blurred.
If Harry was adopted by Hellsing, his education would be very different. He wouldn't be going to Hogwarts to learn magic in the traditional way. Instead, he'd be learning from Hellsing's experts on how to deal with the undead. His social circle would change completely. He'd be surrounded by people like Integra, Seras, and the rest of the Hellsing crew. Their values and goals would influence him, and he might develop a more militaristic approach to dealing with problems compared to his more diplomatic style in the wizarding world.
Well, he might become a really powerful vampire hunter. With his magical skills from the wizarding world combined with Hellsing's training and resources, he could be a force to be reckoned with against supernatural threats.
His story would be radically different. He'd be part of a vampire hierarchy instead of the wizarding world's social structure. His goals might shift from defeating Voldemort to dealing with vampire - related issues, like vampire - human relations or power struggles within the vampire clans.
His story would change drastically. For one, his view of family would be different. Ashoka could provide a more loving and nurturing family environment compared to the Dursleys. His magical education might also be influenced. Maybe he would learn to combine magic with Ashoka's combat skills. His character development would be shaped by Ashoka's teachings on morality and leadership.
His living conditions would change drastically. Instead of living with the Dursleys, he'd be in a palace. He'd have servants and a much more luxurious life.
If Harry Potter is adopted by the Autobots in fanfiction, the story would take on a whole new dimension. Harry would be exposed to a completely different way of life and technology. His understanding of the world would expand beyond the magical realm. He might use the Autobots' technology to improve his magical devices. And the Autobots could use Harry's knowledge of magic to their advantage in their own battles. This would also introduce a new element of mystery and excitement to the story as the two different worlds collide.
He would probably be more in tune with nature. The Inuzuka's lifestyle would make him more aware of the natural world around him. He might be less bookish than in the original and more hands - on with physical activities like running and training with the clan.
His view of heroism would change. Hellboy is a very different kind of hero compared to the wizards in Harry's world. He's more of a brawler and has a darker, more gritty approach to fighting evil.
His life would change drastically. He'd be surrounded by Death Eaters and the dark side of magic. His values would be challenged, and he might not have the same friends. He could become more feared in the wizarding world.
He'd probably become more brooding. Growing up with Dracula would expose him to a darker side of magic and life. He might not be as quick to trust others as he was before. His sense of humor might also change, becoming a bit more sarcastic and dry, like the typical Dracula - like characters.
He'd probably have a different accent. And his diet might change too, more burgers and fries perhaps. His view of the wizarding world could be more influenced by American values like equality and freedom.