Well, Snape is a complex character. If he discovers that Harry was raoed in a romance fanfiction, he would probably be filled with a mixture of emotions. First, there would be disgust at the very idea of such a thing happening to Harry. Then, he might feel some guilt, as if he should have been able to prevent this (even though it's in a fictional scenario). He would most likely want to confront the person responsible for writing it, and he would also be more vigilant about Harry's well - being. He might even start to see Harry in a new light, with a deeper understanding of the potential vulnerability that Harry could have.
Snape's view of Harry might become more sympathetic. He would see Harry as a victim rather than just an annoying student. This could lead to a softening of his attitude towards Harry in general.
In the fanfiction world, if Snape found out Hermione had been raped, he might first be filled with a cold rage. He could use his skills and influence to seek out the perpetrator. Given his complex character, he would likely take justice into his own hands in a very Snape - like way, perhaps using his knowledge of the Dark Arts to exact revenge while also trying to protect Hermione from further harm and the public eye.
In some fanfictions, Snape might be secretly sympathetic. He may see the scars as a reminder of all Harry has been through, which could soften his usually harsh attitude towards Harry, at least for a moment.
He would probably be very displeased. Snape has always been strict and traditional, and fanfiction about the DA, which was an unauthorized student group in his eyes, would seem like a frivolous and inappropriate thing to him.
Snape's initial reaction would be one of disbelief. He has his own set of prejudices and ideas, and gay romance fanfiction is far from his realm of understanding. He might snatch the fanfiction away from Harry in a fit of annoyance. But as he sees Harry crying, he might start to wonder what in this strange piece of writing has such an emotional impact on Harry. This could lead to a very awkward and tense moment between them, with Snape not knowing how to handle the situation properly.
Harry's reaction would be complex. He has so many emotions tied up with Snape already - dislike, confusion, and a bit of grudging respect in some ways. Discovering he's his father would bring all those emotions to the surface and more. He might go through a period of denial, not wanting to believe it at first. Then, as the truth sank in, he'd have to come to terms with a new family member. He might also feel a sense of betrayal from those who knew or suspected but didn't tell him. And he'd have to figure out how to fit this new relationship into his life, especially considering his role in the wizarding world and his ongoing battles.
In the fanfiction world, Snape might be initially shocked. He has a complex relationship with Harry. He could feel a sense of protectiveness that he rarely shows openly. He might use his skills and knowledge to find the perpetrator and seek justice for Harry.
Snape would likely be shocked and then enraged. Harry is supposed to be the hero of the wizarding world, and seeing him drunk would be a huge disappointment. He would most likely drag Harry to his office, lecture him about propriety and the expectations placed on him as a wizard, and probably assign some form of punishment like a long detention. But as he observes Harry more closely during this time, he might start to wonder what drove Harry to this and if there are deeper issues that need to be addressed.
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.