One way it could be justified is through a dark magic plot. Maybe Voldemort uses some powerful and ancient magic to bind Hermione to him against her will at first. But as time goes on, she starts to understand his past traumas which led him to become so evil, and in a twisted way, tries to reform him. However, this goes completely against the original good - evil divide in the Harry Potter series.
Perhaps in the fanfiction, an alternate universe is created where the prophecy was misinterpreted. Instead of Harry being the one to face Voldemort, it's Hermione. And through a series of events, Voldemort becomes obsessed with her power and intelligence and tries to make her his mate. But this is a huge deviation from the canonical story where Voldemort is only interested in power and domination.
Well, in fanfiction, the author has the liberty to play with the lore. There could be a scenario where a powerful dark magic spell in the past had some unforeseen consequences. This spell could have somehow intertwined the bloodlines of Voldemort and Hermione's family. Maybe a curse was placed on a family that later branched out to both Voldemort and Hermione's ancestors, creating this strange connection.
Well, in fanfiction, some authors might come up with the idea that there was some hidden connection or a secret affair in the past. Perhaps Voldemort had a relationship with Hermione's mother before he fully embraced the dark side. This would completely change the dynamics of Hermione's character and her place in the wizarding world. It could lead to her having to deal with the stigma of being related to the most evil wizard ever while still trying to uphold her values.
Well, in fanfiction, the idea of Hermione being Voldemort's niece might stem from some sort of magical tampering with family lines in the past. It could be that a powerful spell was cast long ago that altered the relationships in a way that made Hermione related to Voldemort. Or it could be a completely different take on the lore where the wizarding world has a whole other layer of hidden family connections that JK Rowling didn't explore in the original series.
In fanfiction, anything can be possible. It could be due to some dark magic or a convoluted plot twist. Maybe a spell was cast long ago that altered Hermione's true parentage, or Voldemort could have used some form of mind control on her real parents to make them believe she was theirs when in fact she was his. However, this goes completely against the original lore of the series.
Well, in fanfiction, anything can be made possible. Maybe a long - lost family connection was revealed. It could be that there was some sort of secret adoption or a hidden family tree branch that ties them together. Writers of fanfiction often take creative liberties to explore such unique relationships that were not part of the original story.
Well, in fanfiction authors often take creative liberties. It could be part of an alternate universe scenario. For example, if there was a different timeline where the wizarding families were arranged differently. Hermione might have been adopted into the Black family (Narcissa's family) through some complex set of circumstances, like a deal between two powerful wizards to protect her from some dark force.
In fanfiction, the idea of Hermione being Draco's mother can be made possible through alternate timelines or magical interventions. For example, a powerful spell could have altered their family relationships. It allows writers to explore different character dynamics and how it would change the story.
Well, in fanfiction, anything can happen. It could be that a spell or some magical accident in the past led to Hermione and Pansy being sisters. Maybe a time - traveling wizard messed with the past, causing their family trees to merge in a way that made them related. It's a really interesting concept that allows for a whole new set of character dynamics and storylines to be explored.
Well, in fanfiction, the author has the freedom to twist the original story. For McGonagall to be Hermione's mother, perhaps there was a powerful charm placed on Hermione as a baby to hide her true parentage. And McGonagall, being a powerful witch, had reasons to keep this a secret, like protecting Hermione from some dark forces that were after her because of her heritage.
In fanfiction, anything can be possible. Writers often bend the rules of the original universe. Maybe it could be through some sort of time - travel magic that Hermione goes back in time and meets Salazar. Or perhaps there's a magical spell that binds their fates together in an alternate reality created by the fanfic writer.