“Well done, Mr Potter.” Professor Sprout handed back his test paper. “A pleasing improvement on last term’s result. Some of us are late developers. Better late than never, I say.” She waddled off, stiff-legged, her muddy Wellington boots reaching half-way up her short thighs, making it impossible to bend her knees as she walked.

Harry was astounded: he had come top in the Herbology test. He’d dropped a few points on the ‘Herbal Identification’ section, but on all the questions to do with sowing, propagation, germination, pricking-out, watering and pruning he had gained full marks. What was it his Aunt Petunia had been preaching at him all summer? ‘We reap what we sow.’ She would be horrified if she knew she had been furthering his magical education.

Professor Sprout stumped back into the greenhouse carrying a smallish paper bag in her plump hand.

“Can you give this to Professor Snape for your next lesson?” she asked Harry, “And be very careful not to drop it.”

Potions classes no longer filled Harry with terror. He had always hated Snape. From the moment they had met he had sensed a mutual dislike, a natural antipathy to one another, which Snape had fostered through his unrelenting intimidation and bullying tactics. Harry’s hatred had been borne of fear, helplessness and injustice. James’ letter, however, had legitimised this hatred, giving it a direction, a focus, a goal. The hatred had become manageable, a strength, not a sign of weakness. When Harry looked at Snape now, he felt not cowed but superior.

And, ironically, as his fear lessened, so his brewing skills increased. He even found himself enjoying making the potions, appreciating the subtleties of the delicate recipes, and savouring the finesse of the intricate techniques.

If Snape was aware of this change in attitude - and Harry had, more than once recently, caught the Potions master eyeing him with a questioning, contemplative frown on his face - he was scrupulous not to compliment Harry on his performance. He remained as distant and coldly aloof as ever.

He stalked into the dungeon now, silencing the class with a scowl. There was an air of waspish irritability about him this afternoon; a man not to be crossed. Without preamble, he shot his wand at the blackboard where a complex list of ingredients and instructions immediately appeared.

“Proceed!” he barked.

They did not need telling twice.

Harry studied the Potions master, searching for some outward sign, some evidence… …of what? He wasn’t sure. It wasn’t as though the Dark Mark would surround him like a visible satanic aura.

In the Astronomy Tower the previous evening, Harry had at one point steered the conversation to the subject of Voldemort. Guarded, but not hostile, and censoring his words with care, Malfoy had informed him that, yes, the Dark Lord was indeed regrouping, attempting to re-establish his power-base, his supporters joining in secret cabals throughout the country. A meeting was planned for that very night. All the Death Eaters would be summoned to Voldemort’s presence to pledge their allegiance.

Malfoy wouldn’t say exactly how he had known the time of the Death Eater gathering. Harry assumed he still had contacts amongst Voldemort’s inner circle, even with his father, Lucius, imprisoned in Azkaban. For all Harry knew, the entire Malfoy family could be concealed under those anonymous white hoods. Presumably it was only a matter of time before Draco took the Mark himself. The precise source of the information was immaterial to Harry, just so long as it was accurate.

Suddenly uncomfortable under Harry’s scrutiny, Snape glanced up from the scrolls he was marking. Harry noted, with some gratification, that he did look tired. The idea of Voldemort’s having given Snape a hard time was hugely appealing.

“Concentrate on the Potion, Potter!” he warned.

Yet again their eyes locked sights on each other, primed and ready to fire.

Harry stood up. Slowly and deliberately he moved towards Snape. The class steeled themselves for a show-down. Harry placed a paper bag on Snape’s desk.

“Professor Sprout asked me to give you these, Sir.”

When he spoke, Snape’s voice was quiet, smooth, business-like - and laced with menace.

“This week we have been considering the speed at which a Potion will take effect, and evaluating the factors which influence the rate of absorption into the body.

“These include… …anyone?” He threw the query at the class, but without waiting for a reply continued impatiently, “ …dilution, toxicity, viscosity, the carrier medium - whether a liquid, paste, poultice, vapour or tincture - the method of administration - inhalation, ingestion, injection - and the physical condition of the recipient.

“Last lesson we compared the retardant properties of which four decelerants? Potter?” The question hit Harry like a sniper’s bullet.

“Um…”

“Viper’s Tongue, Spungewort, Arachnium and Powdered Slothshell!”

Snape spat the answer. “Today we are studying Accelerants. The most commonly used is the Puff-Pod. Easily cultivated, widely available, this plant has powerful properties of dispersal and propulsion. A minute quantity is sufficient to render the effects of even a slow-acting poison virtually instantaneous.

“I will provide each of you with a Puff-Pod,” he said, reaching into the paper bag. “Handle it with caution. They are extremely volatile.”

Harry examined the small, non-descript pod that Snape put in front of him. It was about the size and shape of a Fwooper’s egg, rusty brown in colour and with a hard, brittle casing. He had seen one before. Fred and George used them, treated with Sparkle Spell, as a propellant in some of their larger fire-crackers. The twins had also been known, at the height of their Filtch-baiting campaign, to leave the pods lying in the corridors like tiny, organic land-mines, awaiting the feet of unwary first years.

“The only safe way to…” Snape began, but was cut short by a gasp of dismay from Pansy Parkinson. She had picked up her Puff-Pod and had accidentally let it slip into her bubbling cauldron.

“STAND BACK!” Snape roared. “GET AWAY FROM THERE!” Diving across the room he flung himself between the cauldron and the stricken students.

“GET DOWN!” he screamed, spreading his arms and cloak out wide to shield them from the blast.

The cauldron erupted. Spores, ash, potion magma and soot vented upwards in a molten dust storm. A dense mushroom cloud of gagging smoke billowed through the room; the air was thick and gritty with reeking fumes.

Harry took charge.

“OUT!” he shouted. “Crawl out. Don’t breathe.”

They gained the corridor, eyes streaming, and lay on the floor coughing and clearing their clogged lungs.

Hermione was the first to notice that Professor Snape was still inside the classroom.

“Do you think he’s OK?” she asked in alarm.

“Don’t see why not. It’s only dust,” Harry replied scathingly.

She regarded him reproachfully and, too late, Harry remembered that he was supposed to care.

Snape had taken the full force of the explosion. He was still standing, in shock, by the remains of the cauldron, covered from head to foot in a choking layer of dust, dark flakes of powdery ash and congealing splatters of potion.

“Are you alright, Sir? You’d better sit down.”

Harry took Snape by the elbow and guided him to a chair. The Potions master submitted, unable to speak. He took a few dry, gasping breaths, then sneezed violently three times. Clouds of dust flew up as he moved, only to re-settle.

“Draco!” Harry ordered, “Get him some water!”

Harry allowed his hand to rest lightly on Snape’s shoulder.

“You’ll be alright, Sir.” he said gently.

Snape gave him a long, searching look, uncertainty vying with distrust. The moment lengthened. Then he snapped:

“Get your hand off me, Potter!”

He rose shakily but decisively to his feet and directed his wand at his plastered robes.

“Vestimenta purgo!” he croaked. “Now, clean this place up! Fetch Filtch. Where’s Parkinson?”

“What’s going on, Potter?”

The voice was icy enough to be Snape’s, but it was Malfoy, accosting him in the corridor. “What was all that about? One minute you’re telling me you can’t stand the sight of him, that you hate his guts, and the next minute you’re nursing him like some injured Puffskein. What am I supposed to think? All that rot about ‘honour’ and ‘revenge’ - you didn’t mean a word of it.”

“It’s all true, Draco, Merlin’s honour!” Harry took the Slytherin aside and lowered his voice:

“That was just a red-herring, to keep him guessing. Did you see how he was, sort of… …disconcerted? I don’t want him getting too suspicious. He might take precautions. Or tell Dumbledore. Anyway, I had to do something to shut Hermione up. I do hate him and I am going to get revenge. And if you don’t believe me, you can use this!”

Harry indicated a tiny, glass phial hidden in the inside pocket of his cloak.

“What is it?”

“Veritaserum. I nicked it just now, in all the fuss.”

The Slytherin looked impressed.

“You’re on. Tonight? In the Owlery?” Malfoy walked quickly away.

“Who’d have thought one little seed pod could make so much mess?” Hermione joined Harry on his way back to the common-room. “I wouldn’t like to be in Pansy’s shoes right now.”

“Snape wasn’t too chuffed, was he?” Harry smiled at the memory.

“Wasn’t it lucky it was a Painless Potion we were brewing,” laughed Hermione, “otherwise it would have scalded him.”

“Yeah, a real pity,” agreed Harry, not listening.

Hermione took Harry’s arm and gave him one of her little squeezes.

“I was so proud of you in there, Harry. You were great. The way you took charge, and everything. And how nice you were to Snape. You’re really trying with him, aren’t you? It’s wonderful to see the two of you making friends.”

Harry thought grimly, ‘I’m not going to make friends with him, I’m going to kill him.’