Whoever scheduled Double Potions for first thing on a Monday morning had to be a complete sadist. Harry decided that Snape must have arranged the time-tables. He took a desk at the back of the class and tried to look inconspicuous. From the minute he had woken up he had been steeling himself for this moment: if he could just get through the first Potions lesson without cracking and giving the game away, then he knew he’d be able to keep himself in check.

The thought of being in the same room as Snape, breathing the same foul air contaminated by his mere presence, let alone speaking to him, gripped Harry with a sick fury. Just the sight of the man made him want to spit in his smug, supercilious face, to hit him, to smash him, break him, hurt him - really hurt him - and make him pay for all those years of cupboards, hunger, locked doors, bruises; pain and grief and loneliness and lies...

He clenched his fists, tightly squeezing imaginary lemons, then relaxed his fingers to release the tension. ‘Not this, not this, not this…’ he repeated to himself, ‘let it go, let it go, let it all go…’. As the Occlumency training kicked in, Harry felt his hatred subside; mirror-smooth cliff walls encircled his mind.

The dungeon door opened and Professor Snape swept into the room, in a swirl of black fabric. His boots made no sound whatsoever on the flagstone floor as he strode to the front of the class.

“Abbot, Boot, Brocklehurst, Granger, Malfoy, Parkinson, Potter. All present?”

“Yes, Sir.”

“Potter!”

“Sir?” Harry couldn’t believe he was being singled-out already. He hadn’t done anything - yet.

“Front, Potter. This is a NEWT class. Students do not skulk at the back.” With a minimal movement of his finger he indicated the empty seat on the front row next to Draco Malfoy. Then he turned to the class:

“If any of you are having second thoughts about your choice of Potions as a NEWT subject, kindly leave the room now.”

Nobody moved; they barely dared breathe.

“Some of you,” Snape continued menacingly, his gaze focussed directly on Harry, “are here on sufferance, against my better judgement, and are on probation. Any lapse in standards - of work or behaviour - will result in instant dismissal from the class. Is that understood?”

“Yes, Sir.”

While Harry was moving his bag and equipment, Snape had picked up an official looking letter from his own desk. He now read it, frowning.

“Very well.” They heard him mutter.

Turning to the seven students he addressed them in tones of undisguised contempt:

“The Ministry of Education has, in its wisdom, instructed that the first lesson of the term shall take the form of a ‘revision of principles, procedure, and best practice relevant to the subject in question, making appropriate use of visual aids and mnemonic material wherever possible’.” He paused for a moment, thinking, then continued with disdain,

“Loath as I am to reduce your education to the level of a parlour game, we shall therefore re-cap. Thus…”

He flicked his wand at the black-board and three large flamingo-pink letter ‘P’s appeared.

“The three keys to successful Potion making: Preparation, Precision, Patience.” As he spoke, the words wrote themselves up on the board in Snape’s own impeccable script. He continued smoothly:

“Potion making is an exact science. It requires attention to fine detail, a high level of concentration, meticulous documentation and…” he referred to the Ministry letter with a snort of disgust, “… observance of Health and Safety Guidelines (p325, #5, para. 4b).

“Long hair – if you have it - ” he directed a malicious smirk at Harry, “is to be tied back and jewellery removed. Cauldrons will be maintained in perfect brewing order at all times. They are, under no circumstances, to be used as flowerpots, planters, receptacles for unspeakably unhygienic items of Quidditch equipment, or…” his glance now rested coldly on Hermione, “…cat baskets.”

As he spoke he glided silently between the desks, critically checking their scales, their slicing implements, pestles and mortars. Harry flinched as the man passed behind his desk.

“Correct terminology can be vital to the success of a potion,” Snape went on. He sounded bored now - this part of the spiel was evidently a stock routine - but Harry could tell that beneath it all he was passionate about his subject. He really gets off on this garbage, Harry thought.

“If the recipe requires an ingredient to be powdered, it is not to be crushed; ground does not equal grated; a solution is not the equivalent of a dilution; boiling is not necessarily synonymous with bubbling; simmering may or may not involve steaming; one strains a sediment but skims a scum; a whisked Potion will differ from one that is whipped.”

With another deft twitch of his wand, he replaced the pink Ps with a silvery green acrostic:

Sequence

Timing

Utensils

Direction

Ingredients

Origin

Utilization

Safety

The words shimmered in list formation for a moment, then one by one marched across the board and dived into a graphic of an empty cauldron.

Unamused, Snape concluded his resumé:

“The essential elements to consider in the preparation of a potion are, as you see, the sequence in which the ingredients are added, the timing of such (also referred to as the ‘interval’), the utensils i.e. copper or gold cauldron, wooden or metallic spoon, the direction of stirring, the origin of the ingredients - that can make an incalculable difference to the final result – the use to which you intend to put the eventual product, and, of course, the safety aspects which we have already covered. Are there any questions?”

To say Harry was flabbergasted was an understatement. He chanced a quick grin at Hermione and raised his eyebrows. Looking equally stunned she gave him a ‘thumbs up’. In five years of lessons he had never heard Snape say anything even remotely helpful, constructive or explanatory about the brewing of potions. Why hadn’t he told them all this at the beginning, when they needed to know it, not when they had spent five years painstakingly finding out the hard way by trial and error, learning by their mistakes and earning themselves innumerable detentions in the process? Survival of the fittest? He knows his stuff, Harry grudgingly conceded, but he’s still a bastard.

The ‘bastard’ gave a final, dismissive glance at the Ministry letter then touched it with the tip of his wand. For a second the paper hovered, then began to crease and crumple and curl at the edges, ripping itself into uneven fragments which jerked a few times in mid-air then crumbled to dust and disappeared with a whispery whine. Snape turned back to the class, a curiously satisfied expression twisting his sour features.

“Enough infantile theory,” he barked. “Potter, Parkinson, Boot, Malfoy! Come here!”

Hesitantly they approached Snape’s desk. On it he had lined up four identical glass phials, each containing a clear, colourless liquid.

“There is one further fundamental point to consider when dealing with potions. You will each choose a bottle and, at my instruction, you will drink the contents.”

Four heads nodded glumly.

“Malfoy!”

Draco stepped up with a confident swagger, picked up the nearest phial and, without hesitation, swallowed the liquid. Snape caught him as he pitched forward, unconscious, and lowered him to the floor.

“Sleeping Draught,” he commented matter-of-factly. “Parkinson!”

After some dithering, Pansy selected the centre of the three remaining bottles and sipped it nervously. The class watched, entranced, as the colour of her clothes and body began to change and blend, adopting and mimicking the black, grey and brown shades of the wooden table, the board, wall and floor until she was virtually indistinguishable from her surroundings.

“Chamaelixir. Similar in its effect to a Disillusionment Charm. Limited in its application. An Invisibility Cloak is more versatile,” Snape said, shooting a barbed look at Harry.

Boot was next. He took a brave gulp, grimacing as the bitter taste hit the back of his throat. They all stared at him expectantly.

“How are you, Boot?” Snape asked him, casually.

“Actually, Sir, I’ve got a lousy hangover. Wish we hadn’t smuggled that Firewhisky into the dorm last night. I’ve hardly been able to keep my eyes open all morning.”

“Indeed? A singularly enlightening demonstration of the effectiveness of Veritaserum, I think. Ten points from Ravenclaw. And, finally, Potter!”

Fourteen eyes were fixed on Harry as he raised the tiny phial to his lips. He paused for an instant, bracing himself for some kind of painful humiliation. He wouldn’t have put it past Snape to poison him. At the very last moment, when the acrid fumes rising from the liquid were already misting Harry’s glasses and stinging his face, Snape lunged forward and swatted the phial out of his hand. It crashed to the desk, the glass shattering on impact. Immediately the stench of burning wood filled the classroom as the caustic potion scorched through the desk lid and began searing its way into the drawers, while corrosive drips ate little craters in the stone floor.

“And that is concentrated Streeler venom.”

Harry returned to his seat in shock. The Professor administered antidote to the other three then, nonchalantly flicking a few drops of neutralising anti-venom about the room, he directed his wand at the desk.

“Reparo!”

Like a film played backwards in slow motion, the wood began to rebuild itself before their eyes.

“And what conclusions can you draw from that little experiment?” Snape demanded icily. Hermione raised her hand.

“We have to be careful…”

“That is stating the obvious, Miss Granger. And …?”

“Don’t drink potions?” suggested Hannah Abbot. Snape gave her a withering look.

“BE WARY OF UNKNOWN SUBSTANCES!” he exclaimed in exasperation. “Treat them with the utmost caution and suspicion. Use your common-sense - if you possess any. None of you knew what these liquids were. Yet you drank them because I gave them to you. You trusted me. Why? TRUST NO ONE!” he hissed.

Harry suspected that the subject had now widened to include more than just potions.

Snape checked his watch.

“As we now have only a short time left, we shall prepare a relatively quick, uncomplicated potion, designed to combat biological infestation of creatures such as Chizpurfles . It can be sprayed - onto upholstery, for example – or taken by mouth as an infusion if the problem is of a more personal nature.” Snape gave a malevolent sneer. All eyes were on Harry. Determined not to react, he set his jaw and began chopping peppermint leaves.

The bell rang at last and the class packed up their equipment, thankful to have survived.

“Oh, Boot?”

“Yes, Sir?”

“Detention, after supper tonight.”

Harry felt that, for once, he had got off lightly.