Hermione stays out of Snape's dungeon for a few days. She's feeling fine, physically, but she just feels like they both need some space after their emotional exchange. She is also conflicted out the ethics of the promise she extracted from Snape. She knows the difference between forbidding lies and asking for out right honesty, but still, she wonders if she has erred. Snape had seemed relieved, though he had tried to hide it. Considering she could have asked for anything- up to and including his own death, asking him not to lie to her seemed a small thing in the moment. Now, she isn't so sure. She hopes, someday soon, she can ask him about it. For now, she just wants to create a comfortable, professional distance between them.
Outside Hogwarts, a veritable political shit storm is brewing over the dissolution of House Slytherin. A huge scandal erupts when over half the board of governors is found to be under the influence of the imperious curse. The culprit, of course, is never identified.
To make matters worse, the remark that Hermione made to her fellow Gryffindors at the welcome feast somehow makes it onto the front page of the Daily Prophet, and of course, pandemonium ensues.
Hermione finds herself back in Snape's dungeon a few days earlier than she had planned just to escape from the ruckus caused by the article. Gryffindors slapping her on the back in the corridors in support, Slytherins hissing in green and silver packs and she passes them by- she finds herself running headlong into Snape's office and slamming the door behind her with a shout of frustration.
Snape looks up from grading papers. "That bad, Miss Granger?" he says conversationally.
Hermione groans and takes her seat in front of his desk. "Please let me brew some polyjuice potion, Professor," she says, "I just want to walk through this school without being cheered OR jeered."
"Perhaps being quoted in the Prophet wasn't the best idea?" he says.
"Idea?" Hermione says. "As if I had anything to do with this?"
"The quote did sound like you," he says.
"Oh, I definitely said it," Hermione says, "At the dinner table at the welcome feast. Not to the daily fucking prophet." A look of pure horror crosses her face. "I am so sorry sir. Truly I don't know what's come over me. Please forgive me."
"You're forgiven. I'm still taking twenty points. I'm glad you've grown more comfortable with me Miss Granger, but I am still your Professor."
"Of course sir, believe me, I'm mortified." And she is.
"I believe you. Now, are you here to relieve me of the tedium of grading?"
"Yes, sir," she says. "I'll have it done in no time."
"Good," he says, rising up out of his chair. "I've got a batch of blood replenishing potion to do for Poppy, You can come help me if you finish before ten."
"Yes, sir," Hermione says, and sits down quite cheerfully to the task of grading abysmal third year assignments.
A few minutes before ten, she still hasn't finished when Snape comes back into the office. Hermione looks up at him, her eyebrows raised. "I'm sorry, sir, but I haven't managed to finish yet."
He waves his hand dismissively, but he looks worried. "I'm concerned for your safety, Miss Granger. There has been some loose talk in the Slytherin common room."
"Really?" replies Hermione, "What kind of talk?"
"Threats made against you," he replies bluntly. "I have no doubt you can handle yourself, Miss Granger, but-" He trails off, as if uncertain how to broach something with her.
"Sir?" she asks, trying her best to look unconcerned when she is anything but.
"With your permission, Miss Granger, I would like to place a charm on you."
"What exactly would it do?"
"Two things. It will let me know where you are, and alert me if you are in real distress, or if someone attempts to use magic against you."
Hermione raises her eyebrows at this. "Let us set aside the privacy implications for now, professor, but purely from a practical standpoint - I'm a teenage girl who attends a school of magic. I am in distress, and my friends cast spells against me, every day. How are we going to explain you popping up every time Ginny casts her bat bogey hex, or every time I get a little emotional?"
Snape smirks at this. "The charm is one of my own devising, Miss Granger. It won't alert me every time you have a friendly duel in the hallway between classes. And it knows how to differentiate between an excitable adolescent and one whose life is being threatened."
"And the privacy implications?" asks Hermione. "Do you really feel entitled to the knowledge of my whereabouts when I'm not with you?"
"No, Miss Granger, I acknowledge the charm will be a gross violation of your privacy. But given the nature of the promise I've made you, I can give you my word that I will not attempt to locate or otherwise spy on you unless I believe you to be under immediate threat."
Hermione can't doubt the honesty of his intentions after a statement like that. "Is there truly a credible threat against me, Professor?"
"I believe so, Miss Granger. I am… deeply troubled by the threat and its implications. Please believe me when I tell you I will be working night and day on my end to remove it." Snape looks deadly serious, and Hermione believes him, of course.
"Then I consent to the Charm, Professor, but- I have to warn you- I still suffer some pretty serious aftereffects from the war. I have nightmares that could set the charm off. I'll need your assurance that you won't come barging into my dormitory."
"I'll set some extra protection wards on your dormitory, Miss Granger. If the charm alerts and you are in bed, I won't disturb you or your roommates."
"Roommate," Hermione says. "I live with Ginny in the Head Girl's room, sir."
Snape nods, and then, before she can think of any other objections, quickly casts the charm on her.