Dumbledore could also be an interesting side character in these fanfictions. He has so much knowledge and power. He might be guiding Hermione from the shadows, giving her hints on how to deal with Greyback. His wisdom could play a crucial role in Hermione's survival or in turning the tables on Greyback.
Luna Lovegood can be a really interesting side character. Her unique perspective on the world and her rather unorthodox magic might help Hermione in unexpected ways. Maybe she can sense Greyback's presence in a way others can't or provide some sort of charm or spell that gives Hermione an edge.
Neville Longbottom could be an interesting addition. He's come a long way in terms of his courage and magical abilities. He might stand by Hermione and fight alongside her against Greyback. His connection to plants and herbology could also be used in creative ways to fend off Greyback, like using some sort of enchanted plant to trap or repel him.
One common plotline could be Hermione finding ways to outwit Fenrir Greyback. For example, she might use her intelligence and knowledge of magic to set traps or create diversions. Another could be other characters coming to Hermione's rescue, like Harry and Ron realizing she's in danger and using their skills to protect her from Greyback.
Another storyline might involve a time - travel scenario where Hermione goes back in time and encounters a younger Fenrir Greyback. She attempts to change his path, to prevent him from becoming the cruel werewolf he is known to be in the future. This could involve her using her knowledge and magic to offer him a different future, but facing many challenges along the way.
There's a fanfiction called 'Greyback's Redemption Arc'. In it, Fenrir Greyback saves Hermione from a group of Death Eaters. The author might have written it to explore the idea of redemption for a character like Greyback. Maybe he saves Hermione because he sees her as a symbol of the good in the wizarding world that he has lost touch with, and this act of saving her could be the start of his journey towards redemption.
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.
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).
A possible plot is that Hermione, in her pursuit of equal rights for magical creatures, decides to reach out to Fenrir Greyback. At first, he is hostile, but Hermione's determination and her ability to see beyond his monstrous side start to change him. They could end up in a situation where they have to work together to stop a greater evil that is targeting werewolves and other marginalized magical beings. This would involve Hermione using her logical thinking and Fenrir using his knowledge of the werewolf underworld.
One interesting plot could be Hermione trying to use her intelligence to outwit Fenrir Greyback. Maybe she's on a mission to rescue someone he's captured, and she has to use her magic skills in new and creative ways. For example, she could use a combination of transfiguration and charms to create distractions while she sneaks around his lair.
One interesting storyline could be Hermione using her intelligence to outwit Fenrir Greyback. For example, she could create a spell or potion that repels werewolves like him. Another could be a scenario where Fenrir tries to capture Hermione for some dark purpose, but she manages to turn the tables on him with the help of her friends. Maybe she could also find a way to cure Fenrir's lycanthropy, leading to a change in his character.
I'm not sure if there is such a specific fanfiction. It seems like a rather dark and unusual pairing considering Fenrir Greyback is a werewolf known for his brutality. However, the world of fanfiction is vast, and there might be some out there that explore this concept, but it's not a common or mainstream idea in the Harry Potter fanfiction community.
One popular fanfiction in this vein might be 'The Greyback Incident' which delves into the dark encounter between Fenrir Greyback and Hermione. In this story, it shows how Hermione uses her wits to try and escape the clutches of Greyback. However, the overall tone is quite tense and filled with a sense of danger as Hermione is in a very perilous situation.