Naruto's character development would be a fascinating journey. He would start to see the world from a different perspective. Alucard's influence could make Naruto more cautious, as he realizes the true nature of power and danger. His relationships with others in the ninja world would also change. He might be seen as an outsider, or he could use his new knowledge and abilities to bridge the gap between his two worlds. Naruto would have to balance his old ninja self with the new self influenced by Alucard. He could develop a more nuanced view of good and evil, as Alucard's actions are not always clearly defined in terms of morality. This would make Naruto a more complex and interesting character in the fanfiction.
Naruto's character could become more brooding. Growing up with Alucard, he might be exposed to darker aspects of life earlier. But he could also become more confident in his power, as Alucard is extremely powerful. His sense of justice might be influenced by Alucard's own moral code, which is different from the ninja code.