Snape had finally moved all his things into the headmaster's office. I stood before the stone gargoyle, trying to remember how to get in. I hadn't been here in a few years, when I first transferred to Hogwarts. Dumbledore and I had had met several times, as he wanted to be sure I was adjusting well. I wished that I'd known him better.
"I need to speak with Professor Snape," I finally told the gargoyle.
Everything was silent for a moment while my message was relayed, then the statue leapt aside, exposing a spiral staircase.
"Thank you," I said as I passed the gargoyle, even though it was probably unnecessary.
When I reached the top of the stairs, I knocked on the door. It was quite thick, made from dark wood, and had silver finishings. It was lighter with a golden knob the last time I was here.
"Enter," Snape said, and I obeyed. The office was quite similar to how I remembered- filled with books, lined with portraits of headmasters passed. The tinkering machines were gone, replaced with jars and bottles containing all sorts of specimens and potions. There was a slight chemical smell. I noticed the twinkling eyes of Dumbledore's portrait, and he smiled at me.
"I have Mr. Malfoy's reply, sir," I announced, brandishing the letter.
He held out his hand, and I gave him the reply.
"Loiter there a moment more, Miss Greengrass," he ordered as he unraveled the scroll.
I paused a moment, taking in the green and silver decor. The walls were filled with books. "Why me, sir?" I asked him, breaking the silence.
"You were so desperate to prove yourself, and as I said, my colleagues were preoccupied."
It didn't take a legilimens to know that he was lying. I waited patiently, more annoyed than nervous.
"Very well," he said as the parchment went up in flame. "I have another errand for you."
"Anything, sir," I said. So it was as I suspected. He sent me on a fool's errand just to see if I would read the very "important" letter. He was testing my loyalty.
"After dinner tonight, meet me in the west bell tower. I have a unique job for you."
"Yes sir," I replied.
"You may go."
"Yes sir."
I left his office feeling a twisted sense of pride. I'd been right all along, my double agency would pay if. It just took patience.
I asked myself if I would have done anything differently if Ginny hadn't of kicked me out. Maybe I would have brashly read the letter, and sent the DA into some kind of ambush. Or maybe I would've simply been too nervous, and someone would have noticed and deemed me untrustworthy. There was no way to know how things might have gone differently.
After classes, I ate my dinner quietly. When Snape rose from the staff table, I quickly finished up and followed. It felt like everything was happening so fast.
The Bell tower was just chiming 7 o'clock when I found Snape waiting, watching the school grounds. The sun had not-quite-started to set, so that the shadow of the forbidden forest stretched across the school grounds.
"Come over here, Miss Greengrass," Snape said waving me over. As I came closer, I had the intrusive thought that he was going to push me over the edge.
"Look across the grounds, towards the horizon," he instructed. "It is only during the twilight hours that it may be seen."
I strained my eyes, looking for something. "What is it I'm looking for, professor?"
"Something obscure. Not so much a thing, but a force."
I continued to look out, and noticed something in the air. Some sort of ripple, just barely glimmering.
"Is it some kind of… barrier?" I asked.
"Perceptive," he replied. "What you see is a shield that surrounds the entire school. It is a collection of dozens of ancient enchantments that protect the school from any who wish to harm it."
"Why are you showing me this, Sir?" I asked.
"The Dark Lord has ordered me to remove most of these enchantments," he replied. "He wishes to keep students inside, but for himself and his followers to be able to come and go freely."
My heart dropped. Disarm Hogwarts, which would protect its students to it's own ruin? How could I do anything to hurt this school? I had my issues with some students, certainly, but I loved Hogwarts. It was a home to me.
"What do you need me for?" I asked.
"You are going to undo some of the enchantments."
"But… why?" I was struggling to hide my panic. Snape seemed to notice, but it didn't give him pause.
"Some new enchantments can easily be undone, but the older ones are more difficult to break. They have conditions."
"Conditions?"
"Indeed. They can only be undone by someone who truly loves and wants what is best for the school and it's students, who removes the enchantments of their own true convictions and free will."
"So you need someone who thinks it's the right thing to do, who doesn't intend to hurt any students, and genuinely loves Hogwarts."
"Yes."
Obviously most the new staff couldn't do it, because they didn't care about protecting the students. The older staff couldn't either, because they wouldn't think it's the right thing to do. No students could be forced to do it, either. I wasn't sure why Snape couldn't. It might be a number of things.
"Sir, I do love Hogwarts," I said honestly, "But I can't say I think that's the best thing to do. What if I can't do it?"
"Greengrass, whatever happens on this roof will remain a complete secret," he said. "If you can't do it, that will simply be all."
"Okay," I said with a sigh, my stomach heavy. "How do I do it?"
"There are several runes, like this one here, around the castle. I will take you to the ones we must undo. Stand in the window here, point your wand towards where you saw the barrier."
I pulled my wand from my pocket, standing where he had indicated. It was quickly getting darker.
"Sometimes sacrifices must be made for the greater good, Miss Greengrass."
I took a deep breath and raised my wand. If I couldn't remove these spells, I could only imagine what kind of hell would be rained down on this school. Perhaps it truly was for the greater good, but I was scared. Maybe doing what Voldemort wanted was the only way I could keep the students safe. Death eaters would have better access to the castle, but so would the good guys. It would easier for the DA to come and go, to get supplies, to smuggle students outside.
I searched myself desperately, trying to justify what Snape wanted from me.
"Protego Exsolvio," said Snape.
"Protego Exsolvio," I repeated.
A beam a white light shot from the tip of my wand and crashed into the barrier, creating a just visible ripple. The rune on the wall beside me flashed red.
A single tear ran down my face. I could somehow feel the castle's trust in me, it's rarely given obedience. Part of me still felt like I'd committed a betrayal.
"Well done," Snape said as I roughly wiped away the tear. "Come with me, there are several more."
By the end of the night, I was emotionally and physically exhausted, but I couldn't rest yet. I needed more information. I went to the library and read everything I could get my hands on, until Madam Prince shooed me out. Finally, I knew what to do.