It could develop with Harry having to choose between the two worlds he now belongs to. He might start using Lucifer's power to solve problems in the wizarding world, but that would lead to unforeseen consequences. For instance, if he uses dark magic to defeat Voldemort, the wizarding world might not accept him as a hero. And as he gets more involved with Lucifer, he could lose touch with his friends and the values he held dear at Hogwarts.
In such a fanfiction, Harry's life would take a very different turn. Since Lucifer is a powerful and often mischievous or evil figure in many stories. He could introduce Harry to a world full of demons and other supernatural beings. Harry would have to struggle with his own identity and values. For example, he might be tempted to use Lucifer's power to get revenge on those who wronged him at Hogwarts, like the Dursleys or Draco Malfoy. But he also has the good nature that he got from his parents and friends at Hogwarts. It would be a constant battle between the good in him and the dark influence of Lucifer.
Harry would likely become more complex. He might start to have a darker edge to his personality as he is exposed to the occultist's ways. Hermione and Ron would be very concerned about him. They might try to rescue him from the occultist. Hermione could become more determined to study about the occult to understand what Harry is going through.
Harry's character would likely become more independent and self - reliant. Alduin may not coddle Harry like some of his Hogwarts mentors did. He'd have to learn to fend for himself in a strange new world. His sense of adventure would be heightened as he explores Alduin's domain. Also, his view of magic would expand greatly, which could make him more confident in his abilities.
His character would probably become more humble. Elves are not as prideful as some wizards, so Harry might adopt that trait.
He could become more shrewd in his dealings. Goblins are known for their business acumen, and living with them, Harry would be exposed to their ways of negotiation and deal - making. This would make him more cautious and calculating in his interactions with others.
His character would likely become more conflicted. Harry was always a symbol of good in the original series, but under Grindelwald's influence, he'd be exposed to different ideas of power and control. He might start to question his own beliefs.
Harry's character would likely become more open - minded. Since the OC family is different from the Dursleys and even Hogwarts, he'd be exposed to new ideas. For example, if the family is very laid - back about magic use, Harry might become more experimental with his spells.
He would become more street - smart. Growing up with Bruce Wayne, he'd learn about the darker side of the world much earlier. His magical abilities would still be there, but he might use them more discreetly.
In this fanfiction scenario, Harry Potter's character development would be a significant departure from the original. Initially, he would be confused and a bit scared in this new environment. But as he grows up with Vlad Plasmius, he would start to adapt. His confidence might grow in a different way, not based on his status as 'the boy who lived' but on his own abilities and what he has learned from Vlad. His moral compass would be challenged as Vlad may have different ideas about justice and power. Harry might become more of an outlier in the wizarding world when he does interact with it again, as his values and behavior have been shaped by his upbringing with Vlad. He could also develop a sense of loyalty to Vlad that conflicts with his loyalty to the wizarding world, leading to a complex internal struggle as he tries to figure out who he truly wants to be.
Harry's magical abilities might develop differently. Amelia Bones could provide him with different types of magical education. He might focus more on defensive magic and legal aspects of magic, given Bones' role. His sense of justice could be shaped by Amelia Bones' own sense of right and wrong. This could lead to a Harry who is more methodical in his approach to fighting evil, rather than the sometimes impulsive Harry in the original series. Also, his social skills could be enhanced as he would be around Bones' circle of friends and colleagues, making him a more well - rounded wizard.