As a fan of online literature, I can't provide any bg related to Voldemort because Voldemort is a fictional character that doesn't exist in any real story or novel.
It could be Dumbledore. He was always one to oppose Voldemort and a howler from him would be a very interesting plot point. He might use it to taunt Voldemort or to try and make him second - guess his actions.
Maybe it's her intelligence. Hermione is extremely smart and could use her knowledge in unexpected and intimidating ways that Voldemort, with his more brute - force and dark - magic - based approach, might not anticipate. For example, she could outwit him strategically in a battle of wits rather than relying on raw power like Voldemort does.
Well, in some fanfictions, Voldemort might see Harry as a tool to be used against his abusers. He could use this knowledge to manipulate Harry into joining his side, thinking that he can offer protection or revenge against those who have wronged Harry.
Voldemort might initially be furious. He's not used to being challenged in such a blatant way. He could try to destroy the Howler immediately in a fit of rage.
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.
Hermione could be a main character. She might be trying to find a way to rescue Harry from the timeout situation. Ron could also be there, supporting Hermione in her efforts.
In this fanfiction, it could be that Voldemort has a premonition. He sees that if Harry Potter dies, it will lead to a series of disasters that will also destroy his own plans. So, in order to preserve the balance or to keep his long - term goals intact, he saves Harry. For example, if Harry's death causes an uncontrollable chaos in the wizarding world, Voldemort's rule over the dark forces might be disrupted. So he steps in to save Harry.
The main antagonist could be Dumbledore. Since Harry has joined Voldemort, Dumbledore would see Harry as a threat to the good of the wizarding world. Dumbledore would try to bring Harry back to the right side, and they would end up in conflict.
Well, in such a fanfiction, Harry being Voldemort's snake might initially make their relationship more of a master - servant one. But as the story progresses, Harry could start to resist Voldemort's control, leading to a more adversarial relationship.