Another possibility is that Voldemort wants to convert her to his side. He might see Hermione's intelligence and magical abilities as valuable assets. He could try to persuade her with false promises or by showing her the so - called 'power' of the dark side.
Voldemort may also try to extract information from her. Given Hermione's vast knowledge, he might think she knows secrets about the Order of Phoenix or Dumbledore's plans. He could use various dark magic methods to force her to talk.
She might become more distrustful. After being betrayed, it's natural for her to question the motives of those around her, even her closest friends.
Mrs Black could be so offended that she starts to plot against Hermione. For example, she might try to get Hermione into trouble with the Hogwarts authorities by spreading false rumors about her.
Well, Snape is a rather strict and no - nonsense teacher. He might be initially shocked or appalled. He could give Hermione a stern lecture about focusing on proper academic work instead of fanfiction. Maybe he'd even deduct house points if he thought it was a waste of her time or inappropriate.
One consequence could be that she is forced to perform dark magic against her will. This would be a huge moral struggle for her, as Hermione is a firm believer in the light side of magic. It could also change her perception of herself and her magic abilities in a very negative way.
One consequence could be that the wizarding world falls back into chaos and fear. Voldemort would likely start his reign of terror again, targeting those who opposed him before. He might also try to seek revenge on Harry for initially defeating him.
She might gain some vampire - like abilities such as enhanced strength, speed, and senses. For example, she could be able to run faster than normal wizards and have better night vision.
She could use her intelligence to outwit Voldemort. Maybe find a loophole in the security around her and make her escape.
In the wizarding community at large, he could become an outcast. Other wizards and witches would likely look down on him, and he might find it difficult to get support or make alliances in the future. His actions could also lead to him being targeted by those who support Hermione and want justice for her.
One possible consequence could be that he is immediately sent to Azkaban. Since he's a known traitor, the wizarding world would want to punish him severely for his crimes, which include betraying the Potters and framing Sirius Black.
After Harry kills Voldemort in the graveyard in the fanfiction, the magical balance might shift. With Voldemort gone, some of the dark magic that was prevalent might start to fade away. The Hogwarts School of Witchcraft and Wizardry could see a new golden age. New spells and magical theories might be explored as the fear of Voldemort no longer holds back the wizarding scholars. Harry himself might start to travel around the world to spread the news of Voldemort's defeat and also to learn more about different types of magic. His friends would also have new opportunities, like Hermione might be able to further her studies without the constant threat of Voldemort and Ron could finally relax and enjoy a more peaceful life at the Burrow.