Their relationship could develop as a sort of teacher - student dynamic in a way. Fenrir has a lot of knowledge about the dark side of the wizarding world that Hermione doesn't. He could share some of that knowledge with her, while Hermione could teach him about the values of the good side, like compassion and equality. Over time, they could form an unlikely friendship based on mutual learning.
Their relationship could start with Hermione being a captive of Fenrir. But instead of harming her immediately, he becomes intrigued by her intelligence. As time passes, Hermione might start to see some humanity in Fenrir that others don't, and they could form an unlikely alliance against a common enemy.
Well, it could start with Harry trying to understand the werewolf situation better. He might reach out to Greyback not as an enemy but as someone who wants to help the werewolves. Greyback, initially suspicious, could gradually come to see that Harry is sincere. This could lead to them having conversations about the discrimination werewolves face, and a relationship based on mutual understanding could develop.
Hermione's character could develop in terms of her understanding of the grey areas between good and evil. Saving Fenrir goes against the common perception of him as a monster. This could make her more open - minded and less judgmental. She might start to see that even the most feared creatures can have a chance at redemption.
At the start, Hermione would be appalled by Fenrir's cruelty. She would be enraged that he has caused so much harm to innocent people. But as she delves deeper into getting to know him, she would start to see the complex web of factors that contributed to his behavior. She might see the neglect and discrimination he faced as a werewolf, which could make her feel a bit of pity. However, she would still firmly oppose his cruel actions and try to find a way to either contain or reform him, all while being acutely aware of the danger he poses.
There could be a whole new plotline involving the werewolf packs. Maybe Fenrir Greyback had a specific reason for biting Hermione, and his pack might be involved in some grander scheme. Hermione could be caught in the middle of a werewolf power struggle, having to decide which side to take or how to use her new position within the werewolf community to bring about peace or change.
Maybe Fenrir saves Harry from a werewolf attack one night. Harry, being the empathetic person he is, doesn't immediately condemn Fenrir for his past actions. This small act of kindness from Fenrir plants the seed of a different relationship. They could start to exchange knowledge about magic and the dark forces in the wizarding world. As they get to know each other better, their relationship could evolve from a simple acquaintance to a friendship of sorts, with each learning from the other's experiences.
The relationship could be depicted as a reluctant partnership. Maybe they are forced to work together to solve a mystery that involves werewolf lore and some ancient magic. Hermione is initially disgusted by Fenrir but as they spend more time together, she discovers that he has a tragic past that led to his current state. Fenrir, on the other hand, respects Hermione's power and intelligence. This mutual discovery forms a complex and unique bond between them.
Their relationship might develop through a series of tense encounters. Fenrir might be initially attracted to Hermione's magic and her strong will. As they interact more, Hermione could start to see a glimmer of humanity in Fenrir, despite his monstrous actions. This could lead to a complex relationship where she tries to reform him in some way, while he struggles with his dark nature and his growing feelings for her.
Perhaps it's the allure of the 'forbidden'. Fenrir Greyback is a dark and dangerous character, and exploring his relationship with Hermione in fanfiction might be an exploration of the contrast between light (Hermione) and dark (Greyback).
In one fanfiction concept, Greyback saves Hermione when she is trapped in a magical maze created by dark wizards. Greyback, being a cunning and experienced dark creature, is able to navigate the maze and get to Hermione before the maze collapses or she is killed by the various traps inside. He might save her because he senses that she has a great potential that could be useful to him in the future.