Yes, there are quite a few. Some explore scenarios where Voldemort uses underhanded tactics against Harry in really creative ways. For example, in one fanfic, Voldemort manipulates the magical laws to his advantage during a duel with Harry. It makes for an exciting read as you see Harry trying to counter these unexpected cheats.
One interesting concept is when Voldemort cheats by infiltrating Harry's dreams. He can manipulate the dream world to make Harry doubt himself or give away secrets. It adds a psychological aspect to their conflict. Another is when he cheats by using ancient magic that no one expects. This often leads to Harry having to research and learn new magic quickly to counter it.
One interesting fanfic could be where Voldemort cheats in a magical duel against Harry by using a forbidden spell that gives him an unfair advantage. In this kind of story, Harry might have to figure out a way to counter this cheating without breaking the rules himself.
Some writers create these fanfics because it allows them to explore different character dynamics. When Voldemort cheats, it shows his desperation or his devious nature in a new light. And it also gives Harry a different kind of challenge to overcome, not just a physical or magical one but also a moral and strategic one. For example, if Voldemort cheats by bribing people around Harry, Harry has to decide how to deal with those who have been turned against him, whether to forgive or fight back.
I'm not sure if there is such a fanfic. Fanfics cover a wide range of themes and scenarios, but this particular one might be quite rare or even violate some of the general guidelines of the Harry Potter fanfic community. Many fanfic platforms have rules against inappropriate or non - canon - compliant content.
There probably is. Fanfic communities are full of unique and unexpected plot ideas. This kind of plot would completely turn the original story on its head. It might involve some sort of alternate reality where Harry and Voldemort have a common goal or where they are forced to work together due to some external threat. It could be a really interesting read for those who like exploring different interpretations of the Harry Potter universe.
At first, it would be extremely tense and full of suspicion. Harry would be very wary of Voldemort's motives for protecting him. Voldemort, on the other hand, might be impatient with Harry's lack of trust.
Perhaps Voldemort discovers that there is a greater threat out there. In the fanfic, it could be that another dark force is emerging, and Voldemort sees Harry as an ally of sorts against this new threat. So, he decides to protect Harry in order to deal with this common enemy.
Snape could also be a character in such a fanfic. His complex relationship with both Harry and Voldemort makes him an interesting addition. He might be in a difficult position, having to keep his cover as a double - agent while also trying to find a way to save Harry without revealing his true intentions to Voldemort.
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.