Well, perhaps in the fanfiction, Harry is suspected of stealing potion ingredients from Snape's stores. Snape, being the strict and no - nonsense professor he is, decides to spank Harry as a form of punishment. Or it could be that Harry is involved in some sort of prank that endangers other students, and Snape takes it upon himself to discipline Harry in this rather unorthodox way. These plotlines would likely be used to explore the characters' relationships and reactions in different, non - canon situations.
One possible plotline could be that Harry breaks a major Hogwarts rule, like sneaking into the Forbidden Forest. Snape catches him and decides that a severe punishment is in order, which in this case is spanking. Another could be that Harry fails a very important Potions test repeatedly, and Snape, frustrated with his lack of progress, resorts to this extreme form of discipline. However, these are all just fan - created ideas and not part of the official story.
There might be some fanfiction out there that deals with this in a non - inappropriate way. However, it's important to note that in the official Harry Potter series, such a situation is not part of the canon. Fanfiction often explores different scenarios, but it should still adhere to certain moral and ethical boundaries. Some fanfictions might use this as a form of discipline - themed story within the context of Hogwarts' strict rules and Snape's strict nature, but it's not very common.
One interpretation could be a form of extreme discipline. Snape has always been strict with Harry in the original series, and this could be an extreme version of that strictness. Another could be a comical take, where it's just a very absurd situation used for humor.
One possible plotline could be that Harry discovers a plot against Snape before it's too late. Maybe he overhears some Death Eaters planning to ambush Snape while he's on a solitary mission. Harry then uses his invisibility cloak and magic skills he's learned over the years to outwit the Death Eaters and save Snape. This would show Harry's growth as a wizard and his ability to set aside past differences with Snape.
There could be a plot where Snape's muteness is a secret that he tries to hide from everyone at Hogwarts. The story could be about how he manages to teach Potions and be a double agent for Dumbledore all while keeping this secret. Or perhaps a plot where his muteness is a magical experiment gone wrong, and the story is about his journey to reverse it. Along the way, he might discover new aspects of magic and his own identity that he never knew before.
One reason could be that he realizes Harry has a lot of potential and wants to nurture it. He sees that Harry is in a difficult position, being the target of Voldemort, and decides to help him despite their past differences.
One interesting plotline could be Snape and Harry having to work together on a secret project for Dumbledore. They start off distrusting each other but as they face challenges, they gradually become friends. For example, they might be researching a powerful dark magic spell that Voldemort is after, and in the process, they learn about each other's past traumas and start to empathize.
Some fanfictions have a plotline where Snape survives the Battle of Hogwarts and he and Harry have to deal with the aftermath together. They might have to face the wizarding community's reaction to Snape's past actions and also work on rebuilding Hogwarts. There are also stories where Harry, while still at school, starts to understand Snape's difficult position between Dumbledore and Voldemort and tries to help him in some way, which creates a whole new dynamic between them.
One interesting plotline could be Harry growing up with Snape's guidance and inheriting his potions skills at an early age. He might have a different dynamic with the other Hogwarts students, being more of an outcast due to his connection to the often - misunderstood Snape.
A plot could involve Snape's deaging being the result of a dark magic experiment gone wrong. Harry and Ginny initially suspect foul play but soon realize that Snape is truly a child in mind and body. They decide to protect him from those who might want to use his situation for their own gains. As they do so, Snape begins to form a bond with them, especially with Ginny, who he sees as a sister - like figure. Harry, meanwhile, has to deal with his own mixed feelings towards this new Snape, as he is constantly reminded of the old, often - hated Snape, yet also sees the potential for a new beginning.
One possible plotline could be that Harry travels back in time. In this scenario, he stumbles upon a young Severus Snape being bullied by some older kids. Harry, with his knowledge of Snape's future importance and his own sense of justice, steps in to save Snape. This could then lead to a change in their relationship dynamic. Instead of the animosity that exists in the original story, Snape might view Harry in a different light from the start, which could potentially change the whole course of events at Hogwarts in the future.