In such a fanfic, it would be a very strange and dark twist. Voldemort might use Harry and Hermione to gain more power in a different way. Maybe he wants to corrupt them and turn them against Dumbledore and the Order. He could also try to use their knowledge, especially Hermione's vast magical knowledge, for his own evil plans.
Harry would probably become more conflicted. His views on good and evil would be severely tested. Hermione might become more cunning as she tries to outwit Voldemort while living under his roof. Voldemort himself might develop a strange sort of attachment to them, which could make his actions even more unpredictable.
At first, it would probably be very tense. Harry would be suspicious of Voldemort's motives, and Voldemort would be cautious of Harry's potential to rebel. But as time goes on, they might develop a strange sort of understanding. Harry could start to see Voldemort as more than just a pure evil figure, and Voldemort might start to view Harry as something more than an enemy.
Well, one possibility could be that Voldemort adopts Harry as a way to control the wizarding world. He might think that by having Harry on his side, the resistance against him will crumble. Another could be that Voldemort discovers some sort of connection between him and Harry that makes him want to take Harry under his wing, perhaps related to some long - forgotten prophecy.
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.
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.
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.
A frequent theme is the re - imagining of the magical world. With Voldemort in a different role as an adoptive father, the power dynamics in the wizarding world change. Also, the theme of identity is prominent. Fem Harry has to figure out who she is in this new situation where she is associated with Voldemort. And there's often the theme of moral ambiguity as she may be exposed to dark magic yet still hold on to her own sense of right and wrong.
A possible plot could be that Voldemort adopts Harry after seeing a prophecy that Harry is the key to saving the wizarding world in a different way than just defeating him. So, Voldemort decides to raise Harry in a way that will make him a powerful ally. They go on adventures together, facing ancient magical threats that neither could face alone, and along the way, they form an unlikely bond.
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.