There are fanfictions that explore Snape's relationship with Voldemort in a more psychological way. For example, delving into how Snape's past experiences with Voldemort shaped his actions throughout the series. Maybe Snape has to face some of his darkest memories related to Voldemort and overcomes them in a unique way in the fanfiction.
There might be a fanfiction where Voldemort discovers Snape's true loyalty is not fully with him. This could lead to a really tense showdown between them. Snape would have to use all his skills in magic and deception to survive. Maybe he has to convince Voldemort that he was only pretending to be against him to gain more information for the Dark Lord.
There could also be interesting developments for Harry Potter in such fanfictions. Harry might have a different reaction to Snape. Instead of the complex and often conflicted relationship they had in the original story, Harry could fully embrace Snape as a hero and perhaps learn more about Snape's past and his motives in a more positive light. This could lead to a much closer bond between them, with Harry seeing Snape as a mentor figure in a new way.
Another interesting plot could be a backstory about how Snape first got involved with Voldemort. Maybe it was out of a thirst for power initially, but then his views changed over time. This could be delved into in great detail, showing his transformation from a potential dark wizard follower to a hero in the fight against Voldemort.
One common theme is loyalty. Snape's loyalty to Dumbledore and the Order of the Phoenix is put to the test during the torture. It shows how he endures for the greater good.
There could be a fanfiction where Voldemort saves Harry from another dark wizard. In this scenario, Voldemort has his own motives. He might want to be the one to defeat Harry himself in a more 'honorable' duel later, so he doesn't want some other dark force to take Harry out before he has his chance.
One interesting 'harry goes to voldemort' fanfiction could be where Harry tries to understand Voldemort's motives and in the process, discovers a long - lost magic that could potentially end the war. Another might be a story where Harry is magically transported to Voldemort's side during a battle and has to pretend to be on his side to survive and gather intelligence.
Well, in some of these fanfictions, Harry's magical abilities might change when possessed. He could start using dark magic in ways he never would have before. It makes for a really interesting twist on his character. For example, he might struggle against Voldemort's will while still being forced to do some dark deeds, creating a complex internal battle.
One interesting fanfiction could be 'The Dark Captivity'. In it, Harry is held in a magically fortified dungeon by Voldemort. Voldemort's motives for capturing Harry are explored in depth, not just about killing him but also about breaking his spirit. Another could be 'Captive Potter'. Here, Harry endures various mental tortures while being Voldemort's captive, but he manages to secretly communicate with his friends using a very unique and magical way.
One interesting 'Harry and Voldemort are soulmates' fanfiction could be the one where they discover their soulmate bond during a magical duel. The intense energy of the duel somehow triggers a connection that neither expected.
One interesting fanfiction could be one where James Potter has a pre - battle encounter with Voldemort that changes the course of the First Wizarding War. Maybe in this fanfiction, James discovers a secret weakness of Voldemort that no one else knew about.