Maybe someone who is very creative and looks at the broad concept of magic in both. They could see the heroic aspects of Harry Potter and compare them to Arthur Pendragon's heroism. But really, it's a stretch. Harry Potter has a very different set of rules for magic and a different kind of society compared to the Arthurian world.
Well, some people might be a bit confused or just thinking very outside the box. They could be focusing on the idea of a chosen one in both stories. Harry Potter is the 'Chosen One' to defeat Voldemort, and Arthur Pendragon was sort of a chosen king. But that's about the only tenuous link. The overall worlds, characters, and plots are so distinct that it's a strange idea to consider Harry Potter as Arthur Pendragon fanfiction.
Some people might think this because of the common theme of a young hero on a journey. In both, there is a central character who has to face great challenges and grow throughout the story. Also, the use of magic or some form of special powers is present in both. In Pendragon, there are powers related to the different worlds and in Harry Potter, there are spells and magical abilities. This similarity in the basic structure of the story could lead to such a thought.
It could be that they've seen some really out - there fan theories or crossovers that made them misinterpret things. Some people like to create wild combinations of different fictional elements, and this might have led them to this strange idea. However, in reality, the two are completely separate entities with their own identities and storylines.
Well, maybe someone who doesn't really understand the essence of either could make such a strange claim. They might be confusing the elements of magic in both concepts. But really, it's a very far - fetched idea.
The main characters could include the heir's family members from the Pendragon side, even if they are long - dead, they might appear in memories or visions. Dumbledore could also be a main character as he is a very important figure in the Harry Potter world. He might guide the heir, knowing about their special heritage and seeing how it could be beneficial in the fight against evil. Another possible main character could be a villain who wants to use the heir's power for their own dark purposes.
In this fanfiction, Harry's character development would be a long and interesting journey. At first, he may be in denial about his new heritage. But as he starts to explore it, he'll grow. He'll learn about the values that Arthur Pendragon represented, like honor and courage. These values will be integrated into his own character. His magical abilities will expand as he discovers new powers related to his Pendragon blood. He'll also face new challenges that test his new - found qualities, and through these challenges, he'll become a more well - rounded and powerful character, both in terms of magic and in terms of his personality.
Saber from Fate/Stay Night would be an obvious choice. Since she is also related to the Arthurian legend, there could be a lot of interesting interactions between them. They could compare their experiences as king, or even fight side by side against a common enemy.
Maybe it's just a really out - there and misinformed idea. Some people might be so used to mashing up different concepts in their minds that they make this odd connection, but it has no basis in fact.
Well, it might be a very strange and misinformed idea. Maybe someone who doesn't really understand either franchise very well just made a wild connection in their head. But as we know, Harry Potter is about magic and wizards, and Sonic is about a speedy hedgehog. There's no logical basis for such a claim.
They might be very confused. Maybe they haven't actually read either the Harry Potter books or Greek goddess fanfiction properly.
It could be due to a misinterpretation of some common elements that they think are shared but are actually not. For example, both series have characters with special powers. But the nature of those powers is completely different. In Harry Potter, magic is more about spells and potions, while in Naruto, the Uchiha's power like the Sharingan is a ninja - related ability. People who don't fully understand these differences might wrongly think Harry Potter is an Uchiha fanfiction.