It depends on the specific context and the author's intentions. Sometimes, it might be considered canon, but without more details, it's hard to say for sure.
The main characters are clearly young Joseph and Dio. Joseph is a character with a strong will and unique abilities, especially his Hamon. Dio, on the other hand, is a powerful vampire with his own set of formidable powers.
I'm not entirely sure about the very specific 'real story' of Kars for Kids. But generally, it's an organization that is known for collecting car donations. It uses the funds from these donations for various children - related causes, like providing educational support or care for children in need.
I'm not entirely sure as I haven't read it specifically. But generally, a light novel often has a unique story line, perhaps with complex characters and an interesting world - building. It might involve the adventures of the characters, their growth, and the challenges they face in the world of 'ultimate kars'.
Perhaps a plot point where the power dynamic between them shifts unexpectedly. Maybe Joseph discovers a weakness of Dio that no one else knew, leading to a very tense and exciting confrontation. In fanfiction, this could be something completely new and creative that the author invents.
One idea could be a crossover with the 'Jojo's Bizarre Adventure' universe where Kars interacts with other Stand users. Maybe he forms an unlikely alliance with a hero to defeat a common enemy.
I'm not familiar with the 'ultimate kars light novel' in detail. However, in most light novels, there are usually a protagonist and antagonist. So, Kars is likely the protagonist. As for the other main characters, there could be someone who opposes Kars, perhaps a rival with a different ideology or goal. There may also be characters that are important to Kars's development, such as a family member or a love interest.
The clash of two very different universes makes 'naruto kars fanfiction' interesting. Naruto's world is full of ninjas, chakra, and complex village politics. Kars, on the other hand, comes from a world with his own set of powers and rules. When combined, it creates a unique and unpredictable story.
To start a Kars crossover fanfiction, think about the conflicts that will arise. Kars is used to a certain way of life in his original story. When he crosses over, he'll face new challenges. Maybe he'll have to adapt to a different moral code or a new power hierarchy. This can be the starting point for your story, as you explore how he copes with these changes.