In fanfiction, evidence could be things like Giovanni having a soft spot for Ash that other characters don't notice. The author might write that Giovanni has some knowledge about Ash's past or abilities that seem to suggest a closer relationship. But this is just for the purpose of the fanfiction. In the canonical Pokemon world, Ash's father has not been officially revealed as Giovanni.
Well, in the 'pokemon red is ash's father' fanfiction, the evidence might be quite tenuous. It could be something like Red's influence on Ash's journey in a very indirect way. Maybe the fanfic writer makes Red leave behind some sort of legacy or power that Ash unknowingly inherits. But this is all just speculation within the realm of fan - created stories and not based on the real Pokémon franchise.
Fanfictions often take creative liberties. In the case of 'madara is naruto's father fanfiction', the evidence might be as flimsy as a shared look or a similar power that the author forces to be a connection. But remember, this is all in the realm of fan - created stories and has no basis in the real Naruto lore.
Yes, in some of those fanfictions, the evidence could be things like Snape's long - standing protection of Harry. The idea is that this protection might be more than just a sense of duty to Lily. It could be a fatherly instinct. Also, some fanfics might play with the idea of a magical spell or potion that changed the apparent paternity. But remember, this is all part of the fanfiction world and has no basis in the official 'Harry Potter' canon which firmly states that James Potter is Harry's father.
Often, fanfictions that claim Hermione is Voldemort's heir will create some convoluted backstory. For example, they might say that there was a secret affair between a distant relative of Hermione's and one of Voldemort's ancestors. This would then be used as the basis for her being his heir. However, this is pure invention for the sake of the fanfiction and has no basis in the real Harry Potter story. The original story has no such indication, but fanfiction allows for these wild and imaginative ideas to be explored.
There is no evidence to support such a heinous claim in fanfiction. Fanfiction is often a work of wild imagination by fans, and making such false and serious accusations within it is unacceptable. It goes against the positive and creative nature of fan - created works.
There is no evidence at all. J.K. Rowling started writing Harry Potter on her own, with her own imagination. The series has a clear origin story, from her coming up with the idea of a boy wizard to building the entire wizarding world. Fanfiction usually builds on existing works, but Harry Potter is the original source, not the other way around, especially not related to something as unclear as 'belloch' fanfiction.
In Pokemon fanfiction, the claim that Sir Aaron is Ash's father is often a product of the creative minds of fans. Fanfiction allows for a lot of speculation and alternative storylines. There could be fanfictions where they base this on some kind of time - travel or reincarnation theory, or just a simple connection they make between the two characters' personalities or abilities. But the official Pokemon story has no connection between them, and these fan ideas are just for the enjoyment of those who like to explore different scenarios.
In most fanfictions, the evidence is often created within the unique narrative of the story. Maybe it could be things like similar chakra signatures, or shared memories in a dream - like state. However, in the original Naruto canon, there is no such connection, so it's all fictional speculation within the fanfiction.
There could be various types of evidence. For instance, if the fanfiction delves into the history of magic, there might be a family tree or some ancient texts that imply Harry's connection to Morgana. Also, the way Harry's magic behaves differently from others could be a sign. Maybe his spells have an unusual tint or effect that is related to Morgana's magic. However, without actually reading the specific fanfiction, it's hard to say exactly what evidence it presents.
Well, in some fanfictions, they might point to Harry's extraordinary magical abilities. Merlin was known as a very powerful wizard, and Harry's ability to defeat Voldemort and his various feats could be seen as similar to what Merlin might have done in his time. But it's all in the realm of fan interpretation and creativity.