It could be part of a larger plan to change the wizarding world's view of werewolves. By having a child with Remus, Hermione could be trying to show that werewolves are not to be feared or shunned. She might also be motivated by a personal growth aspect, wanting to step out of her comfort zone and do something radical to make a difference. Also, she may have a strong maternal instinct that she wants to direct towards Remus' situation.
One reason could be her sense of justice and compassion. Remus is a werewolf and faces discrimination, and Hermione might see having a child with him as a way to give him a family and some normalcy in his life.
In fanfiction, Sirius and Remus could fight over Hermione because of their different relationships with Harry. Since Hermione is Harry's close friend, Sirius might think that he should have more influence over Hermione to help Harry better, as he is Harry's godfather. On the other hand, Remus, being Harry's former teacher and friend, also feels a sense of responsibility towards Hermione because of her connection to Harry. This clash of responsibilities and their own personal feelings for Hermione can spark a fight.
One reason could be Remus' wisdom. He is well - read and has a depth of knowledge, which Hermione might find very appealing. Also, his kind and gentle nature, despite his lycanthropy, could draw Hermione towards him. In fanfictions, authors often explore the idea of the underdog, and Remus being a werewolf is an 'underdog' in many ways, and Hermione might be attracted to that vulnerability and his ability to still be a good person in spite of it.
Well, it could lead to a plot where they face opposition from the wizarding community. Some might see it as inappropriate or dangerous considering Remus' lycanthropy. However, they could also find support from unexpected places. The story might then focus on their journey to prove that they can be good parents despite the odds. And perhaps, Hermione's magical abilities could play a crucial role in protecting the child from any threats related to Remus' condition.
Maybe in this fanfiction, Remus and Hermione have shared some deep intellectual conversations that Tonks couldn't engage in as much. Hermione's knowledge of magic, both theoretical and practical, might have drawn Remus to her. Also, Hermione's determination and loyalty could be factors. She is fiercely loyal to her friends and would go to great lengths to protect them, which Remus might value highly.
In the fanfic, it might be due to some sort of magic gone wrong. There could be a spell that made her act out of character. It's not unheard of in the wizarding world for spells to have unexpected effects on a person's behavior and relationships.
Well, perhaps Remus, in his werewolf form, accidentally bites Hermione during a full moon. Then he feels an overwhelming sense of guilt. He might isolate himself from Hermione and the others, fearing that he has put her in danger or turned her into a werewolf too. Hermione, on the other hand, could be in shock and dealing with the physical and emotional pain, but also trying to convince Remus that it's not his fault.
One reason is that it can distort the original characters' personalities. Hermione is known for her intelligence and strong moral compass, and Remus is a complex and somewhat tragic figure. Inappropriate fanfiction might make them act out of character, which can be off - putting for fans who love the original portrayals. Another reason is that it may not be suitable for all audiences, especially younger fans of the Harry Potter series.
Perhaps in this fanfic, the Weasleys have some actions that conflict with Harry and Hermione's values. For example, if the Weasleys were to make a deal with a dark wizard for the sake of their family's safety and Harry and Hermione found out. This could lead to a rift and hatred. Also, it could be related to a love triangle situation in a very convoluted way. Maybe one of the Weasleys unknowingly gets in the way of Harry and Hermione's relationship, or vice versa, which causes animosity.
It could be that they lied to Harry about something really significant. In the wizarding world, trust is built on truth - telling. If they told a big lie, like about the true nature of a magical object that was putting Harry in danger, he would be very angry. And if their actions led to the death of someone Harry cared about. For instance, if they made a wrong move during a fight that caused an ally to die, Harry would find it very hard to forgive them.
One reason could be her thirst for knowledge. Hermione is known for her love of learning, so she might have decided to learn Bulgarian just for the sake of it. Another reason could be related to a relationship, like with Viktor Krum, which gives her an incentive to learn his native language.