Had Crabbe and Goyle had more than one brain cell between them, they would have noticed Draco's altered disposition that night. But they had not, and so they did not.

Draco was distracted, his mind somewhere else entirely. He was imagining scenes in which he shamed Snape and Potter in one action. In which Snape was hideously embarrassed and Potter could never again act the innocent victim in front of all his Gryffindor friends.

He would prove that Harry Potter was no idealised hero.

How he hated Harry.

As a Malfoy, he should be the celebrity in his year. He should inspire awe in everyone - 'there he is,' they would all say as he walked past, 'Lucius Malfoy's son. Lucius Malfoy, the greatest dark wizard since Voldemort himself.'

If it wasn't for Harry, that is how it would be.

Draco's father had told him so.

Draco admitted it to himself quite freely - this plan only revenged himself on Snape as a fortuitous stroke of luck. Its real purpose, as with most things Draco did, was to get to Harry Potter.

That one evening was as long as an ice age for Draco, but eventually they all retired to their dormitories.

Draco waited until he heard the unmistakable snores of his roommates, and then rose. He wrapped himself in a heavy, black cloak, and stealthily crept towards the door.

As the Slytherin portrait swung shut behind him, a shudder of excitement went through him. This was different to all the other mischief he and his friends got up to. This was the most macabre, the most serious, the most devious, the most FUN.

He waited in the shadows outside the Gryffindor common room for what felt like an age. He had not realised that Gryffindors went to bed so late!

He began to doubt . . . had Harry ever come back to his common room? Was there another exit? Had the potion not worked?

But in his heart, Draco knew that this was the perfect plan. No paranoia could puncture his self-belief.

And he was proved right, as the Gryffindor portrait swung open . . . and then swung shut again. It seemed that no-one had emerged.

Draco listened intently, and thought he could just make out footsteps going along the hall.

Invisibility? This Potter boy was cleverer than he had given him credit for.

Draco was just about to follow when he saw the portrait door swing open again.

He watched as Hermione Granger stepped out into the corridor and, with a furtive glance around her, began to follow Harry.

Draco left it a little longer, to ensure that no-one else would be coming out of the common room - and then he began to follow Hermione.

It was no surprise to Draco that they went down and down until they reached the dungeons.

Draco watched as Hermione entered the dark classroom. He waited a little while before daring to glimpse around the half-open door.

Hermione was not there!

Draco entered the classroom, and walked to the study door.

It was open a crack, and through it he could see Hermione, her eye pressed firmly to the keyhole of the bedroom.

He tiptoed to the other side of the same wall, where the wall did not divide the classroom from the study, but the classroom from the bedroom.

He thought that he could just about make out some muffled speech, but he was not sure. The stone was thick and cold.

But just as he was thinking his attempts to eavesdrop were futile, he heard Snape shout 'Harry, please!'

It should have been a chastisement. Snape should have sounded horrified that the prissy Gryffindor was coming on to him, he should have been disgusted.

But what Draco heard in Snape's voice was not disgust or scorn.

It was barely-concealed lust.

Draco was shocked - this was not at all part of his plan.

His plan was that Snape should detest Harry's advances, which would increase in ferocity as the effect of the potion increased, and would have to report it to Dumbledore or somebody in authority. It would be embarrassing for him, yes, but it was Harry who was to pay the price.

Draco quickly adjusted his thoughts to this new piece of information - Snape was attracted to Harry!

He could use this to disgrace them both.

But how to alert the rest of the castle to what was going on?

He couldn't very well go and fetch someone himself; they would ask why he was out of bed.

He found he was desperate to know what was going on in there . . . but no more noise penetrated the thick walls.

He walked and peered round the study door once again . . . and was shocked to see Hermione, who he had labelled as the most straight-laced girl at Hogwarts, lying on the floor of Snape's study.

Her breath was coming in short, violent gasps which she was working hard to keep silent. Her eyes were closed, but beneath her eyelids they flickered wildly in all directions.

Draco laughed inside at the situation he found himself in. It was like something from that trashy fan fiction the Slytherin girls were always writing.

His head filled with ways of using the situation to his advantage . . .if only he could alert someone else at Hogwarts without incriminating himself in the matter!

Just as a self-satisfied grin was crossing his face, Hermione took two deep, heavy breaths and opened her eyes.

She was looking right at him as he peered around the study door.

She stood up hurriedly and began to button her robes, her face blushing even redder than it already was.

Draco marched into the room, trying to look authoritarian and stay completely silent at the same time. As a result, his walking resembled gliding rather than anything else.

Like a fallen angel he grabbed Hermione's arm and pushed her against the wall, his finger to her lips.

The look in his eyes threatened terrible things if she did not keep quiet.

And she did, leaning into the wall as if she wished it could swallow her, watching Draco with wide, scared eyes.

He knelt on the floor and put his eye to the keyhole.

He saw Snape, lying across his bed. Head tilted back, eyes screwed shut, hands gripping the covers, twisting. His mouth was open, and he was moaning.

If Draco had been just a little bit (well, this WAS Draco . . . let's say a LOT) more naïve, he might have thought Snape was in pain.

But Draco was not naïve. Nor was he blind. He saw the messy black head that worked its magic between tensed white thighs.

There was a look on Harry's face that Draco had never imagined possible. He hoped it was just the effect of the potion, but Harry looked positively . . . sexy.

For just a moment, Draco found himself thinking the unthinkable . . . he wanted Harry Potter. Then he remembered himself - this Potter was the cause of everything that was going wrong in his life.

Potter, son of a mudblood mother, famed for destroying his father's master . . . Draco had every reason to hate him.

But, looking through the keyhole, he couldn't help imagining how he would feel in Snape's position. And, he had to admit, he imagined he would feel rather good.

Suddenly he remembered Hermione's presence in the room. He turned, to see her still leaning against the wall.

Her head was spinning and she could not focus her eyes.

Draco stood up, rushed over to Hermione and, grabbing her elbow, ushered her out of the room. He did all this without a sound, but there was no mistaking his intentions.

Hermione was powerless to do anything but obey, and she hurried back to her dormitory, head spinning with conjecture, confusion, and new sensations.

Draco watched her falter as she hurried up the corridor, and laughed mentally.

The he returned eagerly to the keyhole.

Harry was teasing Snape now, kissing now the insides of his thighs, now his stomach, now his hip . . . everywhere but where he wanted to be kissed.

Snape opened his eyes, looked at the seventeen-year-old boy so intent on giving him pleasure. 'Harry, please!' he said. The tone was surprisingly similar to how he had said it before.

Finally Harry gave Snape what he had been begging for.

Draco didn't know whether to feel twisted pity for his potions master's situation; or Iago-esque enjoyment of seeing his plans come to fruition; or triumph over Harry; or amusement.

As it was, he was just feeling very turned on.

He wondered how much it was the potion, and how much natural skill . . . but Harry was fantastic.

From the way he was moving, the things he was doing . . . but mostly by the look on Snape's face . . . Draco could see that this was true.

It was no good, he couldn't lie to himself any more . . . he wanted Harry Potter. In a purely sexual, physical way.

He wanted to make him bleed and cry and scream and writhe in agony. And ecstasy.

He wanted to feel Harry's body squirming under him, rebelling against his touch yet begging him for more.

Draco knew how to make it so that someone hated you with every fibre of their being . . . but still came back for more.

He wanted that for the famous Harry Potter . . . only to a much greater degree.

Draco was sick of all these easy conquests. People knew how evil and generally debauched he was . . . it was common knowledge. He could have had half the school if he'd had wanted.

But all wanted now was Harry Potter.

How about THAT for a challenge?

The heir of Gryffindor and general heterosexual stud. All the stories about Harry and Cho, Harry and Ginny, that Draco had assumed were just idle teenage girl gossip, he began to realise might just be true.

Harry could probably have his pick of any girl in the school.

But Draco had made his mind up.

Harry was going to be his.