In the original series, Harry uses magic that is generally within the bounds of what is considered acceptable in the wizarding world. But in this fanfiction, the use of demonic magic is a huge departure. It changes the whole moral landscape of the story.
The original series focuses on Harry's fight against Voldemort using traditional magic. However, in the fanfiction, Harry's use of demonic magic could potentially make him a more ambiguous character. He may not be the clear - cut hero anymore, and this can lead to a very different kind of story arc compared to the original books.
The relationships in the original series are based on the shared values of the characters. But in the fanfiction where Harry uses demonic magic, his relationships are likely to be strained. His friends may be divided in their opinions about him, and some may turn against him, which is a big contrast to the strong bonds we see in the original Harry Potter books.
Well, in the original series, Harry mainly uses the magic he learns at Hogwarts. But in this fanfic, with the ancient magic, he has access to much older and more powerful forms of magic. This can make his actions and solutions to problems quite different.
In the original series, Parselmagic is mainly associated with the Dark Arts and Voldemort. But in the fanfiction where Harry uses it, it flips that perception. Harry becomes the one using this 'dark' magic for good.
The tone can also be different. While the original Harry Potter series has a certain charm and tone that is aimed at a wide audience, including children, fanfiction can be more targeted towards older fans. It might explore darker themes or more complex relationships between characters. Also, the fanfiction may not be bound by the same level of consistency as the official series, allowing for more creative and sometimes wild interpretations.
One common theme could be the exploration of the consequences of using such dark magic in the wizarding world. It might show how Harry's character changes, perhaps becoming more isolated as other characters fear his newfound power.
In the 'Harry King of Magic' fanfiction, Harry often has enhanced powers compared to the original series. For instance, he might be able to control all elements of magic effortlessly while in the original he had to learn and struggle with many spells.
In the original series, black magic is mostly straightforwardly bad. But in fanfiction, it can be more ambiguous. For example, a character might use black magic to save a loved one from a worse fate.
In the original Harry Potter series, Harry has normal, albeit powerful, magic for a wizard. But in 'Harry Potter Godlike Magic' fanfiction, his magic is often on a whole other level. For example, he might be able to control the elements in a way not seen in the books, like summoning a tsunami with a wave of his hand.
Fanfiction often explores different perspectives. In the original 'Harry Potter' series, we mainly follow Harry's point of view. But in 'Harry Potter and the Fanfiction', we can get inside the heads of other characters like Draco Malfoy or Severus Snape. Also, fanfiction can change the plot. For example, some fanfictions might have Voldemort winning in the end. Another difference is that fanfiction can explore relationships in more depth, such as Hermione and Ron's relationship from a different angle.
The most obvious difference is Harry's identity. In the original, he is a Potter, which shapes his story in many ways. In this fanfiction, not being a Potter means different relationships and a different standing in the wizarding world.
In these fanfictions, it expands the universe by introducing a new form of magic. Rune magic adds a layer of depth and mystery. For example, Harry might use rune magic to access hidden areas in Hogwarts that were previously unknown. It also changes the power dynamics. If Harry can use rune magic, it gives him an edge over his enemies and creates new storylines where he has to keep his new - found magic a secret.