Perhaps a plot where Voldemort discovers that Lucius has been having doubts about his leadership. He then tasks Snape with spying on Lucius. Meanwhile, Harry, through some magical accident, gets involved in this web of intrigue. The story could be about how Harry uses this situation to his advantage to try and bring down Voldemort's regime from within.
Well, perhaps in the fanfiction, they are all entered into a magical tournament. Harry, being the young and brave one, Snape with his vast knowledge of magic, and Lucius with his family's resources. At first, they are rivals in the tournament but then realize that there is an outside force trying to manipulate the outcome for evil purposes. So they join forces. Or it could be that a powerful dark magic spell has been cast over Hogwarts, and only the combined magic of Harry, Snape and Lucius can break it. They start off distrustful but as they work together, they form an unlikely alliance.
A plot could involve Ginny being the key to defeating Voldemort once and for all in a way that no one expected. Since she has a strong connection to Harry, and Harry was once a Horcrux of Voldemort, perhaps her magic has a unique ability to target and destroy the remaining essence of Voldemort. This could lead to a thrilling adventure where Harry and Ginny have to work together in a very different way than before to finally rid the wizarding world of Voldemort's threat.
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 idea could be a fanfiction where Voldemort gets a second chance at life but without his dark magic powers. He has to learn to live as a normal wizard in the wizarding world and Harry Potter has to decide whether to trust him or not.
One interesting plot idea could be that Snape discovers a hidden weakness of Voldemort. Maybe it's a long - forgotten spell that can counter Voldemort's most powerful dark magic. Snape, using his extensive knowledge of the dark arts and his own skills as a wizard, decides to face Voldemort alone to end the reign of terror. Another plot could involve Snape having to team up with some unexpected allies, like a group of students he has been secretly training, to take on Voldemort.
One plot idea could be that in a world where dark forces are targeting Hermione for her intelligence and her role in the fight against Voldemort. Snape, due to his complex relationship with the Order of the Phoenix, and Lucius, perhaps having a change of heart after seeing the true brutality of Voldemort's regime, team up to protect her. They could hide her in an old, magically protected manor that has been in Lucius's family for generations. Snape uses his skills in potions to create protective elixirs for her, while Lucius uses his knowledge of dark magic to set up wards that only they can pass through.
Yes, there could be. For example, in some fanfictions, the marriage might be a part of a complex magical plot to unite the different magical powers. It could also be a way to end the long - standing enmity between Harry and Voldemort. However, this is a very unorthodox concept compared to the original story.
One interesting fanfiction could be about Harry being forced into an uneasy alliance with Lucius in order to gain information about Voldemort's next move. Another might involve Lucius having a change of heart and trying to protect Harry from Voldemort's wrath. There are also stories where Harry uses his connection to Voldemort in unexpected ways, with Lucius caught in the middle of their power struggle.
Well, a possible plot could be that Harry is cursed in a way that slowly changes his values and beliefs. As he starts to side with Voldemort, he begins to enforce new, dark rules in Hogwarts. The other students are in shock and disbelief. Some of his friends like Hermione might try to break the curse, while others like Ron might be more quick to condemn him. Also, Voldemort could use Harry as a tool to gain more support from the wizarding community, as Harry was once seen as the 'Chosen One' to defeat him. So with Harry on his side, Voldemort could deceive many into thinking his ways are not so bad.
One idea could be that Snape endures the torture while secretly passing on vital information to the Order of the Phoenix through a magical link. Another could be that his past with Voldemort is explored during the torture, like how he first got involved with the Dark Lord and his internal struggle between loyalty to Voldemort in the past and his newfound loyalty to Dumbledore.