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.
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.
He'd probably be more sophisticated. The Delacour family is known for their elegance and grace. Harry might have a more refined way of speaking and acting compared to his canon self. For instance, he would be more likely to use formal French wizarding greetings.
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.
He might be more feral. Growing up with a monster, he could lack some of the social graces that a normal upbringing in the wizarding world would provide. He may be more direct and less concerned with propriety.
He might be more laid - back. Canadian culture is often seen as more relaxed, so Harry could have a calmer demeanor. He wouldn't be as quick to get into arguments or be as impulsive as he sometimes was in the original story.
Harry might be more confident in his pure - blood heritage. Since Dorea Black would likely educate him about it, he wouldn't feel as out of place among the pure - blood families as he did in the original story. He may carry himself with more pride, but not in an arrogant way.
If Harry was raised by his grandparents in fanfiction, his personality would change in several ways. For starters, he would be more self - assured because he'd grow up in a loving environment. He wouldn't have the same insecurities that came from being treated as an outcast at the Dursleys. He'd be more extroverted, as he wouldn't be afraid to show his true self. His sense of humor might be different too, perhaps more light - hearted and less sarcastic as a defense mechanism. He'd also have a stronger sense of family and heritage, which would influence his actions and decisions.
He'd be more likely to be initially haughty. Since the Malfoys are known for their pride in their pure - blood status. But he might also grow to be more cunning as he'd be in an environment where manipulation is sometimes used.
His sense of humor would likely be different. Sirius has a bit of a mischievous streak, and Harry would pick up on that. He might be more prone to making jokes and playing pranks in a more light - hearted way compared to the somewhat more reserved Harry we know from the original story. Also, Harry would be more trusting of others in general, especially those in the wizarding world, as Sirius would introduce him to a more positive side of it from the start.
Harry would likely be more fearless and brash. Kenpachi is a bold and fearless fighter, and his influence would make Harry less hesitant. For example, when facing a bully like Draco, Harry might immediately react with physical force rather than just trading barbs. He would be more upfront and direct in his approach to problems.