Well, in fanfiction, when Snape discovers Harry's secret, it's like a bomb going off in their already complex relationship. Snape's entire perception of Harry could change. He might see Harry in a new light, perhaps as more of a kindred spirit than he initially thought. On the other hand, he could feel betrayed if the secret was something that he thought Harry should have shared with him earlier, considering Snape's position in the wizarding world and his role in Harry's life.
Snape's behavior could change drastically. He might become more protective of Harry if the secret was something that made Harry vulnerable. Or he could become more distant if the secret was something he disapproved of.
Well, it depends on how the author writes it. Maybe Voldemort would initially be in disbelief. But once he accepts it, he could start to manipulate Harry in different ways. He might think that by controlling Harry, he can control the Horcrux within him. This could create some really interesting plot twists where Harry has to resist Voldemort's attempts at a much deeper level than just physical attacks.
In such a fanfiction, one possibility is that Snape would initially struggle with his new role as an adoptive father. He has a complex personality, but over time he might start to show his protective side towards Harry and Hermione. He could teach them advanced magic, especially his own areas of expertise like Potions, in a more personalized way.
Well, Harry might become a much more serious student. Snape, being strict, could push Harry to excel in Potions and Defence Against the Dark Arts even more. He might also instill in Harry a sense of discipline that he didn't have before. And Harry could gain a different perspective on Snape, perhaps seeing him as a father figure over time.
In fanfiction, if Snape were to curse Harry with Imperio, it could lead to a complete change in Harry's actions. Harry might be forced to do things against his will, like revealing secrets or even harming his friends. This would create a huge conflict, especially considering his role as the hero. It would also add a dark and complex layer to the relationship between Snape and Harry, which is already full of tension in the original story.
In this kind of fanfiction, perhaps Harry discovers some serious misdeeds by Snape that lead to his dismissal. For example, Snape might be caught unfairly favoring Slytherin students in a major way, like giving them unearned high marks in exams while unduly punishing Gryffindors. Harry, being the observant and just character he is, would report this to the proper authorities at Hogwarts, which could be Dumbledore or the school board. And this could start the process of Snape getting fired.
In this kind of fanfiction, perhaps Severus Snape and Tom (presumably Voldemort in his Tom Riddle form) would have a very different dynamic with Harry. Maybe they would try to shape Harry's magical abilities in their own ways. Snape might use his knowledge of potions and dark magic to train Harry, while Tom could introduce Harry to some of the more complex and dangerous aspects of magic from a different perspective.
If Snape finds Harry Potter fanfiction, he'd probably be quite irritated. He has a rather stern and no - nonsense personality. He might see it as a frivolous waste of time and be disdainful of the creative liberties often taken in fanfiction. He'd likely scoff at the idea of people writing about his students and the wizarding world in such unregulated ways.
In the fanfiction world, if Snape finds Harry cutting, he might be initially shocked and angry. He could see it as a sign of Harry's inner turmoil. Snape, despite his complex relationship with Harry, might feel a sense of responsibility. He might immediately take steps to stop Harry from further harming himself, perhaps using his magic to heal the cuts. And then he would likely question Harry about why he was doing such a thing, trying to get to the root of the problem.
Well, it could be a really interesting story. Snape, being the one to adopt Harry, would have to deal with his own complex feelings towards James Potter while raising Harry. He might initially be strict, but gradually, as he sees Harry's own personality develop, he'd grow to have a very deep and loving bond with him. He could also introduce Harry to a different side of the wizarding world, one that is more influenced by his own Slytherin roots.