Far more frustrating than anything Draco Malfoy could say or do, is his very absence over the next few days. I've kept my eyes peeled, certain I must be able to catch him in the great hall for dinner or walking between classes. But nothing. I don't even see any other students with the green and silver colours, as though Slytherin house doesn't really exist at all. When I try to bring this up with Ginny, she just shrugs, mutters something about it being a dead house. Neither she nor Harry have even heard of Professor Snape.

I struggle to hide my curiosity. It even slips out during my weekly phone call to my parents, as I lean against the panelled wall just outside the dorm room, wired receiver pressed to my ear.

"Do you remember the Malfoys?" I ask my mom.

I can picture her, lips thinning and shoulders tightening, in the moments' pause before she answers. "Yes, of course. Lucius and Narcissa. Why do you ask?"

"No reason," I lie. "I think their son's a student here. Draco?"

"That's not likely," Mom says. "The Malfoys send their children to Harvard. Have done for generations, since the school was first established."

"Oh," I mutter. "Maybe I got it wrong."

Surprisingly it's Luna, of all people, who delivers the missing piece of the puzzle that is Draco Malfoy.

We're sat around the small, wooden table in her house, stomachs full on the nourish bowls she's served up for dinner. Ordinarily, the combination of rice and edamame with orange chilli sauce is more than satisfying, but with the cold weather settling in I'm left feeling strangely empty. I try not to think too hard about the steak pies and French fries in the great hall, but wonder idly if there'll be any left by the time I return.

Luna's house is just at the edges of campus, owned by her father, editor of a highly popular holistic magazine. She and Rolf embody this lifestyle throughout their place — woven tapestries on the walls, thick, knitted blankets thrown carelessly across the sofas, jumbles of second-hand books on every surface, faded kitchen counters from fifty years ago. Their wine is homemade and they often pair it with a pipe full of a sweet, sticky herb they grow themselves. I down my glass of red but decline the smoking pipe, as does Harry.

"Is everything alright?" Ginny asks me, over the jazz record playing quietly in the background. "I don't mean to pry, but I've been worried since you were called into Professor McGonagall's office. She can be quite stern."

Of course Ginny would know. Like many of the other students here, her parents went to Hogwarts Academy, and had McGonagall and many of the other professors tutor them during their time, too. In Ginny's case, she also had three brothers graduate before she came, with an extra set of twin siblings who own a hugely successful novelty store and recently appeared on a list of richest young entrepreneurs.

"She just wanted a quick word," I mumble.

I glance down at my hands, terrified to see a table full of sympathetic gazing. I can't imagine it's much of a secret I'm here on scholarship, but none of us will ever say it aloud. Especially not me. The moment stretches out, no noise except the background music, and I decide to speak again, if only to change the subject.

"Although, the most peculiar thing did happen," I say. "There was another first year student waiting when I arrived. Green house colours, says he reports to a professor called Snape. He told me he was studying literature and alchemy, but I haven't seen him in a single class since."

"He must be one of Snape's private students," Luna says in her dreamy voice.

My brows knit together. "Private students?"

She glances at Rolf. "We had a roommate for a few days, at the start of term. It didn't last long, she ended up leaving to join Snape's class. Apparently it's a requirement to stay in the Slytherin dorm. He only accepts students into his house that he teaches privately."

"Multiple degrees at once," Rolf adds. "Plenty of his students graduate with qualifications in almost every subject you can take."

My mouth drops a little. "How is that even possible? Surely that would take years and years."

"He makes it easier for them, I think," Luna says. "Living in the dorm, pays them an allowance. They don't have much else to worry about besides their studies. People call them Salazar's Seven. After Salazar Slytherin, one of the school founders. Apparently he started the tradition."

I exchange a confused glance with Ginny.

"I've never heard of it," Ginny says. "None of my brothers have ever mentioned Snape. The only thing they've said about Slytherin is that it's a dead house, surprised it's even going still."

"It's a sort of… exclusive affair," Rolf says, eyes glazing over as he exhales a cloud of smoke. "Plenty of successful people started out in Salazar's Seven."

"A handful of presidents," Luna nods. "Famous scientists, authors, historians. There's quite a culture and mystery around them, if you know where to look."

A hunger grows in the pit of my stomach. I imagine what it would be like, to graduate Hogwarts with a degree in every subject imaginable, doors open to me in every industry, free for me to pick at my own discretion. Scientists, authors, historians… a chance to learn. To succeed. An opportunity most people in the world could never even dream of.

And then I get mad. Mad that Draco's shaken a fistful of gold at this Professor Snape, some old family friend, and glided on in. Mad that he's getting what sounds like the best tutorage in the country, with no need to worry about a job, or food, or going without a new pair of shoes when the old pair break so that he can afford the required textbooks that week. I feel like McGonagall's put me in competition against a thoroughbred, when I'm no more than a country pony for grazing.

"This roommate," I say, trying to sound less interested than I really am. "How did she transfer across?"

"We don't know," says Luna. "But they all seem to know each other. Through their families, I think."

Harry claps his hands together, eager to change the subject. "So, are you all going to tomorrow night's warm-up game? First string against second string?"

Ginny rolls her eyes. "We wouldn't miss watching you play for the world," she reassures him.

"It's the decider," he continues, growing more animated. "Whoever wins will be the team that represents us against the other colleges all year."

Harry continues to nudge us all through the next day of classes, growing more agitated and, presumably, more nervous as the game draws closer. I'm still distracted, still getting my head around the existence of this Salazar's Seven. I spend most of the day battling myself, fantasising about asking for a transfer, too cowardly to actually so. I think it over and over, finally making a decision during my French class. The first line of my translation paper: Profiter du présent. I take it as a sign. What have I got to lose?

The final bell trills and I take a deep breath, gathering my textbooks and dictionary, clutching them to my chest like a shield. I retrace my steps from just a few days prior, through the halls and up the stairs and along to McGonagall's office where my courage begins to waver. What if I'm interrupting something important? What if she's not even here, but teaching a class? I lift a shaking fist to knock on the door, knowing if I don't do it now, I never will.

"Come in."

Now familiar with the door, I enter slightly more gracefully than last time. Thankfully, the room is empty of anyone but McGonagall, who peers at me atop her spectacles.

"Miss Greengrass. How may I help you?"

I hesitate before answering, searching for the right words. Long seconds are marked by the ticking of the grandfather clock.

McGonagall seems to sense my reluctance. "A toffee?" she offers me.

I shake my head, fidgeting on my feet. "No, thank you. I was actually just hoping to… to ask for a transfer."

A flash of surprise spreads across her face, before rearranging her features into an expression that's almost caring, almost maternal.

"If this is about the scholarship funding," she says slowly, "rest assured that I have absolutely no doubt in my mind, you are more than capable. All your submitted work so far has been of a high quality, higher in fact than some of my third-year students."

"It's not that." I suppress a shudder. "Professor, I'd like to transfer to Professor Snape's class."

At mention of Snape, her lips twitch back into their usual severe placement. "And why is that?"

"Academic opportunities," I mumble.

McGonagall sighs. "I'm afraid that's quite impossible. Admittance to Professor Snape's class is by invitation only."

"Oh." I think for a moment. "Could you maybe recommend me?"

I don't imagine the irritation in her voice. "Even if I wanted to, Miss Greengrass, I doubt it would make much difference. As far as I am aware, Professor Snape has already filled his class for the year, and is happy with his students." Her eyes soften a little. "I encourage you to stick with the literature program. Rest assured, Mr Malfoy's classes with Professor Snape place him at more of a disadvantage than anything. How on earth that young man will manage to earn six degrees concurrently is beyond me."

"Six degrees?!" I feel my eyes widen, my face flush with possibilities.

McGonagall's face pinches even tighter. "I don't know what you have heard, Miss Greengrass, but Professor Snape's classes are nothing short of brutal. Of the seven students in each intake, only two or three will graduate, and as many more will fall ill from the severe pressure involved."

I sigh, with no option but to admit defeat. "I understand."

"Work hard at your literature," she tells me. "And your French. And believe me, when the time comes to evaluate your performance for next year, you will be more than thankful to have far less on your plate than Mr Malfoy."

I nod politely. I shuffle back towards the door, trying to hide my dampened spirits.

"I hope to see you at the deciding game tonight," McGonagall says before I leave. "As patron of the second-string team, I trust you'll be supporting our red and yellow players."

I glance down awkwardly at my navy blazer. "I'm in Ravenclaw, Professor."

"Ah. Yes. Well," she shuffles parchment on her desk, "best of luck to us both."