“Enter,” Snape called, putting down the stack of third-year papers. He folded his arms over his chest and watched impassively as Harry put down his bag and braced himself for what he had to say. Snape did not rise from his armchair.

“Er… don’t we have a lesson now, sir?”

“Yes. Or rather, we have an hour during which the Headmaster has ordained we carry on the farce that is Remedial Potions.” Snape’s eyes were cold, unfathomable.

“Look, Professor, I’m…” Harry took a deep breath. “I’m sorry for what I said last time. I think I trust you now. Could we have real Occlumency lessons, sir?” he said, very quickly, all at once.

Snape raised an eyebrow. “You mean to say, you trust the Headmaster, and so by proxy, you are willing to have some small measure of faith in myself. You went to see him, did you not?”

“He asked me to. We were talking about the war.”

“I did not ask you of the conversation, nor of the instigator. You spoke of Occlumency.”

Harry did not contradict him.

“The Headmaster trusts me,” said Snape. Harry nodded, slowly. “He… has no need of Occlumency lessons.”

 “Right... I know what you’re getting at, sir, but it’s not like that. Professor Dumbledore gave me some advice – he always does – but it’s my mind. My choice. I can’t say I trust you completely, but I’m ready to try.”

“I see.” Snape stood, then, studying Harry from behind his desk. “This is… quite a  development. You do not have any secrets to hide?”

“Don’t you?” Harry looked away; his mouth, it seemed, had again outrun his brain. “Sir?” he hastily added.

Snape’s eyes narrowed and seemed to lower the temperature between them by several degrees, like chips of ice radiating palpable hostility.

Harry got the message. “Sorry, sir,” he mumbled at his shoes. “I… guess not, then.”

“There can be no secrets between us,” said Snape, with a bitterness even Harry could perceive. Dumbledore’s words seemed to play in his ears: I cannot imagine he would want to trust you.

“I know,” he said, very softly.

“Very well.” Snape swished his wand at the chair in the corner; it floated across the room and landed on the other side of his desk. “Sit.”

Harry obeyed, and Snape returned to his armchair. He tucked away his wand and clasped his empty hands on the tabletop. “Look at me, Potter.”

Harry looked up.

“I will enter your mind now. I would cooperate, if I were you.”

The professor’s eyes looked like two dark tunnels, and as Harry stared at them, it felt as though he were tumbling headlong into the abyss. It was not like the previous times, where Snape’s Legilimency was either a very violent affair, or else a subtle, imperceptible probe. He could feel Snape dragging him like a tide out to sea. He tried his best not to resist, though his instincts screamed otherwise.

Harry had not expected his mind to look like this. He and Snape were standing, not in a blank white room, nor even a dark one, but rather, a shapeless, colorless void. He looked around, uneasy at the way the space seemed to be churning around them, and noticed that he held the image of Snape’s face in his eyes; it was almost as though the scene in his office – Snape behind his desk – was faintly etched into the inside of his glasses. He scrubbed them with the sleeve of his robe, surprised that he was able to do so in his mind, but the image stayed.

The professor regarded him calmly, arms folded. “It is natural,” he said. “You cannot make it go away, not would you want to.” Two fingers appeared in the image, and Harry knew that they were Snape’s, though the Snape standing before him did not move. “An awareness of the physical world, while you are immersed in the mental one, is crucial.” The fingers produced Snape’s wand and brought it closer, till it was the size of a broomstick in Harry’s vision, as if to make his point. “It may well preserve your sorry life.”

Harry nodded, paying only half a mind to the routine insult as he squinted at their surroundings. “It’s so… empty,” he said, gesturing around them at the void at large.

Snape smirked. “Surprised, are you?”

Harry scowled then, which only seemed to amuse the man further. “I meant it,” said Snape, “in more ways than just the obvious one. I speak of not only the… lack of substance, but also of the lack of furniture.”

“Furniture? What are you talking about?”

“Your… parlor, if you will, is rather unadorned.”

“My parlor! What does that have to do with anything? You’re having me on, aren’t you!”

“Everyone has a sort of receiving area in the front of their mind. Of course, I mean ‘front’ in the most figurative sense; there is no corresponding physical location. When you think about something, it appears in this space.” Snape looked as though even this short explanation tried his patience. More irritably, he added, “Try it; it should work, even for you.”

Harry thought of Dumbledore, and the headmaster walked out of the swirling edges of the void, ambling easily towards them. It was like a Pensieved memory, but less solid.

Dumbledore produced a bag of lemon drops from within his wide sleeves, and popped one into his mouth.  

“Hello, Professor Dumbledore,” said Harry.

The old man smiled at him, and replied, “Hello, Harry.”

“You can talk to me? In my thoughts?”

“No, he cannot,” Snape interrupted. “You are creating his reaction, Potter.”

“Right. Of course,” said Harry, feeling vaguely disappointed. “So what am I supposed to do now?”

“Recall my remark regarding furniture. Try imagining a chair or two.”

Harry thought of chairs, and his thoughts wandered to the big red armchairs in his corner of the Gryffindor common room. Three of them appeared, followed by the large circular table where he usually did his homework. When he glanced up, Dumbledore had disappeared.

“Professor Dumbledore?” he called. The headmaster slowly materialized next to the far chair, but when Harry moved to take a seat, he found that the table and the other two armchairs had faded mostly out of sight.

“It appears that you can only actively think about one thing at a time,” said Snape, “though I should have expected as much.”

Harry crossed his arms, but found that it did not rile him as much as it should have. The longer Snape stayed in his mind, the easier it seemed for him to ignore the man's insults. Perhaps it was a consequence of playing host, even if in an admittedly unadorned mental parlor.

“Takes practice, right?” Harry asked. He glanced at the spot where Dumbledore had been, but both he and the chair were gone. “I guess that to Occlude, I need to imagine walls around this place all the time?”

“It’s not nearly that simple. Firstly, barriers and shields are not walls in the conventional sense. Secondly, this is but one portion of your mind, and a relatively small one, I should hope. Barricading one room does not protect the entire house.”

“But I thought you said this was the front door or something?”

“Has a house – a fortress, even – no back doors, or windows? That we are in your mind does not excuse you from using it, Potter.”

“I have to seal off all of them, you mean.”

“No. You are far too attached to this analogy of a house. I assume you are aware that your mind is not actually a house.” Snape tilted his head, his lips curling in a vaguely self-satisfied smirk. “You must seal off your entire mind, even – or perhaps especially – the areas you cannot see.”

“Well how do I do that? Sir?”

“Perhaps you require a different analogy. Imagine a city – and do try not to make London sprout up amongst us. Now, were your mind a city, we would be standing in one small park or square, from which it is impossible to see your mind in its entirety. You must build the city wall. But not only around the perimeter – it must also protect your mind above and below.”

“From here? I know I have to imagine walls, but how am I supposed to know where to put them?”

“That I cannot tell you. It is rather intuitive; it is your own mind, after all, so you should be able to sense where it begins and ends.”

“It was intuitive for you, wasn't it? Dumbledore said you're one of those naturals. Well, I'm not, so I can't feel a thing.”

“He told you that, did he?” There was a trace of... something... behind those words, but Harry could not discern precisely what it was. He might have imagined it, though, for it was gone before he could blink. “I suppose it's just as well,” Snape said heavily. “There can be no secrets between us.”

They stood a while, Snape studying Harry as though he were inspecting some particularly complex potion. Harry fidgeted, waiting for the man to say something, and attempted to imagine the red armchairs into existence again, but he could not help glancing in Snape's direction and being unnerved by the man's steady gaze. Finally, Snape said, “I can show you where the boundaries of your mind lie, though the perspective is... less than ideal.”

Without any further warning, the ground beneath Harry's feet lurched and disappeared as he was pulled upwards and sideways and out – until he was hovering next to Snape above what seemed to be a massive lightning storm. It crackled blue and white, emanating what Harry could perceive as thoughts and emotions; it felt like he was eavesdropping on a thousand conversations at once – all of them his own, he realized. He fervently hoped that Snape wasn't listening in.

“There,” Snape said, drawing Harry from his thoughts. “That is your mind. I assume you can hear the thoughts and memories within. This is what the Dark Lord will see when he enters, and unless you manage to construct a complete barrier, the Dark Lord will have access to everything you see before you now, and more.”

“I have to imagine walls around all of that?” He might as well have been asked to stuff a tornado into a box.

“Yes. It is usually done from the inside, of course.”
“All right then. Here goes.” Harry took a deep breath. You're a Gryffindor, he told himself.

Harry narrowed his eyes, as if to stare down the writhing, flashing mass before him. A mottled grey boulder appeared, sitting innocently in midair at eye level. Harry pushed against it with what seemed like pure force of will, shoving it inch by inch towards his mind.

“We don't have all day,” Snape snapped. Harry chanced a sidelong glance in the professor's direction; the man's irritation was apparent in his scowl. Harry supposed that their current suspended state must be rather difficult to maintain; he had trouble with physical hover charms of any prolonged duration, himself. When he looked to where the boulder had been, it was gone.

“Dammit!” he swore under his breath, as he hastily tried to conjure another rock.

“Language, Potter. And just how many of those do you think you will need to build a wall? Are mountains made of stacked boulders?”

“No,” Harry realized, “They're just sheets of rock, aren't they?”

Snape snorted beside him, but Harry ignored it, and bent his will to imagining a sheet of solid marble this time, encasing his whole mind. It was a gargantuan feat, he though, but there was no helping it.

A glimmer of stone materialized, tendrils of white snaking around – even through – the lightning storm. The image grew clearer and clearer in his mind's eye, the force of will leaving him feeling dizzy and disoriented, the massive egg-shaped thing spinning in his vision...

Harry found himself sprawled back in his chair, staring up at the dimly-lit ceiling. Blinking back the fog in his eyes, he tried to sit up but fell back with a groan, a splitting headache pounding in his temples. He slumped forwards, head in his arms, and squeezed his eyes shut. “Sweet Merlin,” he mumbled, “what happened?”

“You attempted to cast your entire mind in stone, idiot boy,” said Snape from somewhere above him. The professor placed a vial of potion by Harry's hand. “Drink this.”

Harry fumbled for it without opening his eyes, nearly knocking it from the desk before managing to close his fingers around it. He pried the stopper from the phial, hands slick with sweat, and brought it almost unthinkingly to his mouth before he stopped and asked, with effort, “What is this?”

“Something you have likely never heard of,” Snape replied curtly. “I would like the vial back, if you manage not to break it.”

Harry wavered a moment before the lancing pain in his head flared once more, and he gave in. He sucked greedily at the potion, cool liquid soothing his dry mouth and scratchy throat. The effect was almost instantaneous. He opened his eyes and picked his head up from the desk. “Thank you, sir,” he said, replacing the stopper in its phial.

Snape said nothing, but banished the empty phial with a flick of his wand. “You are not dead, are you?” he snapped. Gone was the tentative rapport, however uneasy, that had existed between them in Harry's mind.

“Er... no, sir.” He blinked at the professor, confused, but as Snape turned to fix him with an icy glare, it dawned on him. “Oh. Right, I get it. Trust. I know you wouldn't have poisoned me or anything, sir,” he said, though from Snape's expression, he wasn't so sure – but he wisely kept that thought to himself.

“Quite.” The professor looked him up and down, lips curled in apparent distaste, and gave a perfunctory nod. “You are dismissed for the night, Mr. Potter.”

Harry could feel Snape's eyes on his retreating back as he left. It made him uneasy, but then again, he supposed, the man always did.