There would be chaos. Snape is not one to let things slide easily. He'd probably start investigations, interrogate students, and this would disrupt the normal school life. The students involved in the DA or the fanfiction might have to find ways to cover up or face Snape's wrath.
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.
She might be initially defensive. Hermione is a proud and independent character. So, when Snape finds out about her arm, she could be worried that he'll use it against her in some way, like taking away house points or using it as an excuse to give her extra work.
Snape's view of Harry would likely become more complex. He might see Harry as more vulnerable than he previously thought. His initial disdain might turn into a sort of begrudging concern. He would realize that Harry is dealing with deeper issues than just being the 'Boy Who Lived'.
The story could develop in many ways. For one, Snape might lead a secret investigation. This could involve him using his Slytherin cunning to uncover the truth behind the rape. As he delves deeper, he might find out there are bigger conspiracies at play. Meanwhile, Hermione would be struggling with the trauma. Snape's actions towards her could gradually change from just a teacher - student relationship to a more protective and empathetic one.
Snape's reaction could be quite mixed. On one hand, he might be angry at Dumbledore for not doing more if he knew about the abuse. He may also feel a strange sort of empathy towards Harry. After all, Snape himself had a difficult childhood. So, he could start to be a bit more lenient with Harry in his classes and try to subtly offer support.
Snape's reaction could be multi - faceted. He might be angry at those who are abusing Draco, but also a bit conflicted because of Draco's family's ties to the Dark side. He could use his position as a teacher to give Draco some extra guidance and support, perhaps in the form of private tutoring sessions where he can also check on Draco's well - being more closely. He may also start to question his own views on the Malfoy family in general.
Well, if everyone found out Harry was Snape's son, it would completely shatter the existing relationships. For one, Harry's relationship with the Dursleys might be even more strained as they already dislike him, and this new revelation could make them feel even more threatened. His relationship with Ron and Hermione would also be tested. They might be confused and even a bit betrayed at first. Hermione, being the logical one, would probably try to find out how this could be possible. Ron, on the other hand, might have a more emotional reaction. And as for Snape himself, his whole attitude towards Harry would have to change drastically. He couldn't keep up the pretense of hating Harry when it turns out he's his son. It would also change the way the wizarding world views Harry. Some might be more sympathetic, while others might be suspicious of Snape's motives all along.
His confidence would probably soar. Knowing he has his parents, who are likely strong ninjas, supporting him would make him feel more secure. He might become a bit less reckless as he now has people who care about him deeply and he wouldn't want to worry them.
It would likely make him question his identity a great deal. He might start to wonder about his biological parents and what traits he got from them. This could lead to a whole new self - discovery journey in the fanfiction.
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.