Hermione's character would likely become more complex. She might start off as a broken and fearful person due to the abuse. But with Voldemort's influence, she could gain a new sense of power and confidence. Maybe she would become bolder in her use of magic, not just relying on traditional spells but exploring darker or more unorthodox magic under Voldemort's guidance.
Yes, there are some fanfictions with this concept. It's an interesting take on the Harry Potter universe as it flips the typical relationship between Harry and Voldemort. In these fanfictions, the story often explores how Voldemort's actions change when he takes on the role of an adoptive figure to Harry, who has been abused. It can lead to some really unique character developments and plot twists.
Perhaps Voldemort adopts Hermione with an ulterior motive at first, like using her intelligence to further his own dark plans. But as he spends time with her, he starts to develop a strange sort of paternal feeling. Hermione, on her part, could try to subtly change Voldemort's views. She might introduce him to the value of Muggle - born magic and the importance of equality, which could gradually make Voldemort question his own pure - blood supremacist ideology.
A fanfiction titled 'Hermione's Refuge' has Remus adopting an abused Hermione. This story is unique as it not only focuses on Hermione's recovery but also on how Remus has to face the wizarding community's reactions. It shows that their relationship is not without challenges, but through it all, they support each other.
In such a fanfiction, Sirius might have to face various challenges while adopting Hermione. For example, there could be opposition from some parts of the wizarding community who might question his motives or his ability to take care of her. However, Sirius, with his strong will and love for Hermione, overcomes these obstacles. He might also help Hermione develop her magic skills further and give her the confidence she lacks due to the abuse she has endured.
One great fanfiction with this concept is 'A New Beginning'. In it, Narcissa discovers Hermione's situation and decides to take her in. It beautifully shows Hermione's adjustment to living with the Malfoys and how Narcissa protects her from further harm. It also delves into the complex relationships within the wizarding world and how Hermione's presence changes things for the better in the Malfoy household.
Often, Voldemort starts as this purely evil figure. But when he adopts Harry, he begins to show some unexpected softness. For example, he might start to protect Harry from other threats, which is very different from his usual self.
In this type of fanfiction, usually Minerva McGonagall discovers Hermione's situation of being abused. She takes Hermione under her wing. Hermione might then start to heal and grow in a more positive environment. Minerva could offer her protection, guidance, and a mother - like figure that Hermione might be lacking. This often leads to Hermione becoming more confident and showing more of her true potential at Hogwarts, away from the abuse.
One popular one might be 'Voldemort's New Heir' where Voldemort discovers Harry's abused situation and decides to take him in for his own purposes. He starts to train Harry in dark magic, but an unexpected bond forms between them.
One common trope is the redemption arc of Voldemort. In these fanfics, he goes from being the evil Dark Lord to a more caring figure. Another is Harry's struggle with his past abuse and how he slowly heals with Voldemort's new - found kindness.