Harry could become more powerful in a magical sense. And this new power might make him a bit more arrogant at the start. However, as he realizes the responsibility that comes with this power and the potential danger of the Voldemort - part of him, he starts to grow and become a more complex and wiser character. He has to constantly balance his own good nature with the evil he has absorbed, which changes his decision - making process and how he interacts with others.
Well, it might make him more cynical at first. After all, he has just absorbed the essence of the most evil wizard. But then he could use this newfound darkness within him to better understand the bad in the wizarding world and fight it more effectively.
Harry could become more powerful in a way that scares his friends. Voldemort's training might focus on the Dark Arts, which are powerful but dangerous. This could change Harry's magic style. He may become more solitary as his new skills and knowledge set him apart from his Hogwarts friends who follow a more traditional path of magic.
Harry in this fanfiction is likely to be more ruthless. Voldemort's upbringing would make him less empathetic. He may value power above all else and be more willing to use dark magic to achieve his goals. His relationships would also be different. He wouldn't have the same close - knit group of friends as in the original story. Instead, he might be surrounded by Death Eaters or those who follow Voldemort's ideology.
In these fanfictions, Harry's character transformation is quite drastic. He loses his sense of morality. His loyalty, which was once towards his friends and the good side, now shifts to Voldemort. He becomes more power - hungry, willing to do whatever it takes to gain more power, including using dark magic without hesitation. He also becomes more secretive and manipulative, using his former relationships to further Voldemort's goals.
The relationship would become extremely complex. Harry would no longer be able to simply see Voldemort as pure evil. He would be in a state of confusion and moral dilemma. Voldemort, on the other hand, might start to view Harry as a more interesting pawn rather than just an enemy to be killed. They could develop a strange sort of respect for each other, at least on a surface level.
The relationship would become extremely complex. Harry would be confused and conflicted. He's been taught all his life that Voldemort is pure evil, but now he's been saved by him. Voldemort, on the other hand, might start to see Harry in a different light, perhaps as a tool or as someone with whom he can form an unusual bond. It would be a relationship full of mistrust on Harry's part and manipulative intentions on Voldemort's.
This statement is quite unusual. It could be that the fanfiction contains some sort of magical or emotional energy related to Voldemort, and Harry, being a powerful wizard himself, is able to absorb it. This absorption could have various effects on Harry, such as enhancing his own magic, or giving him new insights into the battle against Voldemort. It's a very imaginative concept that plays with the boundaries of the Harry Potter universe.
Often in fanfiction, their relationship can change drastically. They could end up as allies, which would require both of them to change. Harry would have to see past Voldemort's evil deeds, and Voldemort would have to let go of his hatred for Harry. This exploration of character change makes fanfiction so interesting.
Harry might become more cynical. Since Voldemort has seen a lot of dark and cruel things, those memories could taint Harry's view of the wizarding world. He could start to question the motives of people around him more, even those he once trusted, like Dumbledore.
He becomes more conflicted. Knowing he's Voldemort's son, he's constantly in turmoil about his true nature. His confidence might waver as he wonders if he's capable of the same evil as his father.
It changes the canon by introducing a new form of interaction between Voldemort and Harry. Instead of just the typical battles and mind - reading attempts we see in the original books, the 'plugging' concept adds a more invasive and direct connection. For example, Voldemort could directly influence Harry's thoughts and actions in ways that were not possible in the canon.