It would likely be a very different story. Harry might grow up with the pure - blood supremacist views of the Malfoys. He could be trained in dark magic - adjacent skills. His relationships would be flipped, for example, he might be enemies with Ron and Hermione who are seen as 'blood traitors' by the Malfoys.
Obviously, Harry Potter is one of the main characters. And the Malfoy family members, like Lucius, Narcissa, and Draco Malfoy are also main characters as Harry is raised by them.
He might be more reserved. The Malfoy upbringing would likely make him less impulsive compared to his canon self. He could also be more calculating in his actions.
One possible plotline could be Harry growing up with the Malfoy's pure - blood ideals clashing with his own sense of right and wrong. Another might be his relationship with Draco, which could be a complex mix of rivalry and brotherly - like bond.
Well, in this fanfiction, a significant plot point might be Harry's magical education. The Malfoys would likely have a different approach compared to the Dursleys. He might be taught more about the Dark Arts than he would at Hogwarts initially. Also, his relationship with the Malfoy family members, like Narcissa, could be complex. She might see him as a tool for the family's gain at first but then develop some motherly feelings towards him.
Harry would likely be more confident in his pure - blood status, at least on the surface. Since he's raised by the Malfoys' twins, he'd be exposed to the pure - blood elitist culture from a young age. He might be more calculating and less impulsive than in the original story, having learned from the Malfoy family's shrewd ways.
His personality would likely be more reserved and calculating. Growing up with the Malfoys, he'd be taught to keep his emotions in check and think before acting. He might be more aloof towards others outside of the pure - blood circle at first.
He might be more arrogant. Growing up with the Malfoys, he'd be used to thinking his family was superior. He'd lack the humility Harry in the original series has.
In Harry Potter fanfiction, the Malfoys are often portrayed in a more complex and sometimes positive light. Some fanfictions might explore Draco Malfoy's struggle between his family's beliefs and his own emerging sense of right and wrong. He could be shown as having a change of heart, perhaps influenced by his interactions with Harry and his friends. This gives a new dimension to his character that we don't fully see in the original books.
His character might develop in a more self - interested way. Growing up with the Malfoys, he may not have the same selfless hero complex as in the original. He could be more focused on protecting his family (the Malfoys) and their status in the wizarding world.