Well, Harry could sue Snape for discrimination. Snape always seemed to have a bias against Harry just because of who his father was. This unfair treatment over the years could be a strong motivation for Harry to sue in fanfictions. Additionally, if we consider the times Snape took points from Gryffindor unjustly from Harry, that could also be a reason. Harry might decide to sue to get those points back and also to make Snape accountable for his unfair behavior towards Gryffindor and Harry specifically.
In fanfictions, Harry might sue Snape because of false accusations. Snape sometimes wrongly accused Harry of things he didn't do, which could lead to Harry taking legal action to clear his name and get compensation for the damage to his reputation. Also, Snape's role in the whole prophecy business could be a reason. Harry could sue for the way Snape's actions affected his life, as he was always in the crosshairs because of the prophecy that Snape was involved in.
One reason could be the contrast between them. Snape is this brooding, complex character and Harry is the hero. Writers might be attracted to the idea of bringing these two opposites together as mates. It adds drama and a new kind of tension.
In some fanfics, Snape might punish Harry because of his perceived insolence in class. Harry has a rebellious streak, and Snape, being strict, wouldn't tolerate any behavior that he deems disrespectful to his authority as a teacher.
Another reason might be that Harry is suspected of sneaking around in areas where he's not supposed to be. Snape, as a vigilant teacher, may punish Harry to maintain discipline in the school. He may think Harry is up to something related to the ongoing dangerous situations in the wizarding world and wants to keep him in line.
One reason is the complex relationship between Snape and Harry in the original Harry Potter series. Writers are intrigued by this relationship and use the idea of Snape pinning something on Harry as a way to explore it further. It could be a symbol of protection, a sign of a hidden connection, or a device for plot development.
In these fanfictions, Snape might ignore Harry because of his past with Harry's father. James Potter bullied Snape when they were at school, so Snape could be projecting that hatred onto Harry. It's a simple yet powerful motivation for his behavior.
One common reason could be his love for Lily. Since Harry is Lily's son, Snape might feel an obligation to protect him out of his undying love for her. It's like he's trying to preserve a part of Lily that still exists in the world through Harry.
One possible reason could be Snape's long - standing grudge against James Potter, Harry's father. Since Snape had a difficult past with James, he might project that onto Harry. Another reason could be that Snape is trying to protect Harry in a very strange way. He may think that by rejecting Harry, he is keeping him at a distance from the dangerous wizarding world politics and plots that Snape is often involved in.
One possible reason could be that Snape shows a different side to Harry in the fanfiction. Maybe he protects Harry secretly from some hidden threats that others are unaware of, which makes Harry start to trust him.
One possible reason could be his lingering resentment towards James Potter, Harry's father. Snape and James had a long - standing feud during their school days. Since Harry looks a lot like James, Snape might be transferring his old grudges onto Harry.
He also influences her morally. Snape, with his own complex moral code, makes Fem Harry think about right and wrong in different ways. He might show her that there are gray areas in the wizarding world. For instance, when dealing with enemies, he might teach her that sometimes understanding their motives can be more important than immediate retaliation. Snape's own experiences, especially his relationship with Lily, might also make him instill in Fem Harry the importance of loyalty and sacrifice. In many fanfictions, we see Snape as a strict but fair figure in Fem Harry's life, guiding her through the often - treacherous waters of the Hogwarts social and magical environment.