Over the next few weeks, Sev waited patiently for a confrontation with Malfoy; it never came. Did the other boy know about what had happened in the Prefects' Common Room? He remained as arrogantly aloof as ever, giving no hint as to whether his Death Eater contacts had told him or not. Sev was intrigued by this development, but neither raised nor lowered his guard in response; his guard was always up.

James Potter had said nothing - not that Sev gave him a chance to. If he ever felt the need to throw a distraction in their path, it only took a few choice words to set off Sirius. A couple of times he caught James frowning thoughtfully at him, but he always returned the gaze with a cold look or a sneer.

About two weeks after the incident with the poison, Professor Malachite pulled him aside after Defence Against the Dark Arts. "Severus," he said with a nod. "I heard about your quick thinking a few weeks ago; you may well have saved some lives."

Sev returned his sharp gaze levelly. "I did what was necessary," he answered. There was no guaranteeing where anybody's loyalties lay; the trick was to walk the neutral line at all times.

Malachite nodded, stroking his goatee beard. "Nonetheless; very quick thinking. And you haven't been bragging about it, either."

Sev shrugged. "They're not exactly my friends."

"Which makes it all the more commendable." The teacher leaned back against his desk, and regarded his student thoughtfully. "Tell me, Severus; have you given any further thought as to what you'll do when you leave school?"

"That's two years away yet," he pointed out.

Malachite smiled slightly. "Let it never be said that Severus Snape doesn't think ahead. Surely you have some idea?"

"I'm keeping my options open." Sev's ideal career would involve being locked in a room on his own and paid to read books. Failing the practicality of that, he wouldn't be adverse to going into academia; even into teaching, provided somebody could guarantee all of his students would be intelligent. He had found it a surprisingly enjoyable test of his brainpower to tutor Lily, but he couldn't imagine getting much of a kick from hammering basics into the likes of Colin Crabbe.

However, his choice of career was something that would rely very heavily on where his connections with the Death Eaters took him next. Severus had never been the type to try and make plans without knowing all the variables.

Malchite nodded thoughtfully, as if pleased with this response. "Good, good. Always a wise move." He straightened up. "Well, now. You think on it for a while, and if you come to me in your final year, it maybe that I can... open some options for you."

Sev, as he always did, simply nodded and filed the cryptic statement away for future reference.

Christmas rolled on, with little of note disturbing the more mundane aspects of school life. It was both amusing and worrying, Sev reflected, how quickly people just returned to their normal routines in the face of something like the raid at the end of last year. That was how a group like the Death Eaters could come to power in the first place; people preferred to bury their heads and pretend the problem didn't exist than tackle it.

Having only his uncle for family and no particular homing instinct, Sev always stayed at the school in the holidays. It suited him far better than the rest of the year; school was always better when it was close to empty.

At Christmas, he usually received a stack of books from his uncle, and was more than satisfied with that. Mostly his only relative vastly underestimated his academic level, but Sev wasn't troubled by that. There was no such thing as a useless book.

This particular Christmas, however, his uncle's faithful old barn owl was not his only avian visitor. Whilst he was curled up with a nicely complex Arithmancy text, a sleek, unfamiliar eagle owl zoomed in through the window and away again, leaving a small slip of paper to flutter to the ground. He picked it up, and saw that there were only four words written on it.

Midnight. Portkey. As before.

Sneaking out on Christmas night was no particular hardship. Teacher patrols were all but non-existent over the holidays, and right now the vast majority of the staff were no doubt either in drunken slumbers or attempting to head that way.

It was no trouble for him to recollect the route to the Portkey clearing Malfoy had led them to the year before. In fact, Sev had been back in between, and seen that the black-veined rock that was used as a transporter had vanished. In the middle of the Forbidden Forest or not, it had stood out enough that some unlucky student might pick it up.

Clearly, the Death Eater on staff had been back to replace it in time for his midnight jaunt. Sev spent much of the walk contemplating ways to monitor who came back to collect it afterwards, but decided there were none that were sufficiently risk-free.

As he walked, he became aware of curious depressions in the ground. All through the forest there were ruts as if somebody had rolled something with a very wide wheel, or else dragged something heavy. He puzzled over them, but couldn't bring to mind any activity on Hogwarts grounds that could have caused them. Still, there was no telling what lurked within the bounds of the Forbidden Forest...

The teachers all liked to frighten students with tales of the horrible things that could happen if they strayed into the forest, but Sev always had his wits about him. He had a light tread, and he knew how to keep his eyes open; nothing would take him by surprise.

Nothing did, and he made it to the Portkey clearing without seeing anything more menacing than a hedgehog. He knelt down, and pressed two fingers to the surface of the Portkey.

The world fuzzed out and faded in, and he found himself back once more in what he was fairly convinced was Durmstrang School of Wizardry. This time, however, he had materialised not in a nondescript corridor somewhere, but at the base of Voldemort's tower itself.

He looked up into the steely-grey eyes of Professor Dolohov. "Professor," he said with a nod.

"Mr. Snape." Dolohov's voice contained neither warmth nor dislike, only indifference. "He wishes to see you. You know the way."

Snape did. As he mounted the steps, he could feel a small circle of growing heat on his left arm, as if he was resting it against a boiling cauldron. He pushed back the sleeve, and saw that the Dark Mark tattooed there was turning from red back to black.

The upper chambers were dark, but his eyes adjusted quickly enough. "Lord Voldemort," he said, stepping inside.

The handsome Death Eater leader, seated in the far corner, looked him up and down, and nodded. "Ah, Snape. You came."

"I was summoned."

Voldemort nodded, and leaned forward lazily, resting his chin on one hand. "I've heard some interesting rumours."

"About the poison and the Gryffindor Prefects," acknowledged Sev. Voldemort was sharp, very much so, and lying or playing with distraction tactics could be deadly.

"Indeed. Would you care to explain your actions?"

The casually interrogative tone was laced with hidden danger. Sev simply looked him in the eye, and gave his explanation in neatly clipped sentences. "There was a miscalculation. I saw that the poison was adapted from the powder Malfoy used; it was only supposed to affect mudbloods. However, I saw that it had jumped to Potter - and Potter is as pureblood as they come, however... misguided his attitudes. An antidote had to be developed, and I thought it best that I make it myself than allow another to study the poison."

"And why cure the victims?"

"They're two lives, and not important ones. Too insignificant to risk the cause for."

Voldemort leaned back into the shadows, his expression betraying nothing. Sev kept his own as flat, prepared to hold it as long as necessary. After a moment, the Death Eater leader smiled thinly.

"And that, Snape," he said quietly, "is where you and Malfoy differ. He's quick to fire; you're as cool as ice. Tell me, which is better?"

That was a trick question if ever he'd heard one. "Both. Neither," he shrugged. "Different tools for different jobs."

"Interesting." Voldemort still smiled. "Malfoy would have me get rid of you if he could," he pointed out. Sev nodded and shrugged again. "But you would have me keep hold of him? Why?"

"Everybody has their uses."

"Indeed. Indeed, they do." Voldemort stood up. Sev had already obtained much of what would be his full adult height, but the Death Eater leader was far taller. "And I think I will have many uses for you, Severus Snape." He looked Snape up and down. "Provided you still have use for us." His dark eyes fixed on the Prefect badge that held his cloak together. "I see they trust you. Appreciate you. Perhaps you are beginning to think that you would be better off in their order than our one."

It was not quite a question, but Sev answered it anyway. "It seems that way now. It won't take long for them to show their true colours."

"Perhaps. Perhaps not. We shall see." He nodded briskly. "You may go."

His second verbal dance with Voldemort had been as intricate as the first, but Sev was more concerned with what hadn't been said than what had.

Voldemort clearly hadn't believed that his helping of James and Lily had been some sign of rebellion - if he had, Sev would never have left Durmstrang alive. However, the Death Eater leader was clearly concerned that Sev wasn't in deep enough yet; he might still be lured away by the other side.

Sev had to allay those suspicions - preferably without actually throwing himself in too much deeper. It would take some serious nastiness to make it so he had no choice but to be Voldemort's; far better, then, to give himself his own 'reason' for choosing that side. He had to pick his ground very carefully. Fortunately, a little revelation he'd had in the third year provided him with something of a clue as to how to go about it.

It was going to take a long-term approach; measured in months, because of the situation involved. And to achieve his aim, he was going to have to do something that didn't come at all naturally - be totally unsubtle.

It began with the full moon of February. He made a point of watching the base of the Whomping Willow, knowing what he would see but waiting for it anyway.

Sure enough, as dusk began to fall, he saw the procession of James, Sirius, Peter and Remus making their way to the deadly tree. Sirius poked with a stick at something he couldn't see, and the flailing limbs abruptly froze. The four of them ducked under the tree.

Sev waited, but it was a while after moonrise before three of the boys emerged. Interesting; very interesting. In the third year, they'd been looking for a way to stay down there. Obviously, they'd found it.

For anybody who didn't know whatever secret they'd found, however, down there below the Whomping Willow would be a very dangerous place. Sev was counting on it.

The following day, he cornered Pete Pettigrew. The small Gryffindor had gained in confidence a great deal since he first started at Hogwarts, but he was still apt to cave under pressure.

"I saw you last night," he hissed. "Out in the grounds. Where were you going? What were you doing?"

Pete stuttered nervously, and Sirius rushed to his rescue. "Back off, Snape," he warned.

"I know you're up to something," he said darkly. "And I warn you, I will find out what."

"Oh, put a sock in it," groaned Sirius, dragging his friend away. "Come on, Pete." But Sev spotted Remus hanging back, and looking very concerned.

Phase one of Operation Hatred was well underway.

Sev had twigged pretty early that what he needed was a cast iron reason for hating 'the good guys'. And, better yet, he had to do it in such a way that it seemed like their idea.

The four Gryffindor friends were all wild boys, but they had their differences; James was noble, Remus was smart, Peter was nervous and Sirius was impulsive. If he leaned on Peter, the other boy would spill the whole truth and ruin everything. If he went to James, he might well warn Sev out of doing something too dangerous.

That left Sirius Black - an explosion waiting to happen. Sev just had to get all that explosive potential pointing in the right direction.

The chances of anyone realising he knew the truth if he followed them again next full moon were minuscule - but Sev was nothing if not cautious. He 'failed to notice' the March excursion, biding his time until after Easter.

The intervening months, however, he didn't put to waste. He used every opportunity to be 'caught' watching the Gryffindors with a pensive expression. He shadowed them around Hogsmeade on their weekend trips, and asked leading questions of the Hufflepuffs and Ravenclaws - for of course, there was no way a Slytherin would be caught dead talking to Gryffindors directly.

All in all, there could be no doubt in the minds of the four boys that Severus Snape suspected they were up to something. However, they all - except perhaps Peter - shared that Gryffindor trait of belief in their own invincibility. They were Gryffindors - they could outsmart any stupid Slytherin any day of the week.

Sev knew all about that attitude - he was counting on it. Sirius, in particular, would be in love with the idea of pulling a double-cross on sneaky Snape.

So, when the full moon next rose over Hogwarts, Sev was there, watching from the shadows. And the following day, he cornered Sirius after Quidditch practise. He had known Sirius would be alone; he and James were both on the team, but James had been spending more and more time with Lily lately.

"I saw you last night," he said dangerously. "Down by the tree. Don't think you can hide it from me, I saw you go into the passage. Where were you going?"

"Shove it, Snape," Sirius insisted, pulling away from him.

"I could report you, you know." It was exactly the kind of petty, childish ploy that Sirius would think him more than capable of.

Sirius gave him a scathing look. "Your word against ours."

Sev shrugged, showing off his Slytherin badge. "I'm a Prefect."

"So's James. And he's a Gryffindor."

"Get some new prejudices, Black, this one's wearing pretty thin."

"Yeah? Well you're not exactly doing a lot to disprove it." He turned away to go.

"What's under the tree, Black?" Sev called after him. "What are you all hiding down there?"

Sirius simply shot him a less-than-friendly hand gesture, without looking back. But Sev was well satisfied. The seeds had been sown.

By this time next month, he would be ready to put his plan in action.