In the days Sev had spent learning Cuero's secret, Malfoy had not been idle. He had repeatedly mentioned the need for a 'big gesture', but remained tight-lipped about what it exactly it was to entail.

Sev had observed him sending and receiving several letters via his family owl, Meraugis. None of the letters had an address on them and Malfoy never named names, but the owl seemed to know where it was going. Sev wondered if his parents were similarly mixed up with the Death Eaters; Malfoy seldom mentioned his mother and father, except to point out how rich and powerful and important they were.

Finally, the owl returned bearing a parcel that seemed to be the answer he had been waiting for. He gathered the other boys in his dorm, waving the package triumphantly.

"I have it," he announced, with a dark smile.

"Have what?" demanded Avery. "You've been so close-mouthed with this, Lucius, it's like trying to pry sweets from a Hufflepuff." The boys laughed nastily. It was a Hogwarts myth that all Hufflepuffs were fat and unathletic.

Malfoy was still smiling. "I have... the perfect gesture," he said, overdramatically.

"Tell us," begged Colin eagerly.

"I can do better than that... I'll show you. I intend to use this on the whole school - but I do believe a little demonstration is in order before we start." He rubbed his hands together. "First we'll have to find ourselves a mudblood..." He reflected for a moment, then smirked to himself. "Potter's little girlfriend should do nicely."

"No," interjected Sev. His voice was quiet, but forceful.

Malfoy frowned. "Why not?" Sev was satisfied to hear from his tone that he automatically assumed that Snape's objection would be logical, not ethical - not that any wizard of Malfoy's views would be able to comprehend the idea of ethical problems with harming mudbloods.

"If this is the prelude to a big gesture, it'll be noted and followed up on. You can't use Potter's girlfriend because she's Potter's girlfriend. It brings the focus too close to us."

Malfoy stuck his lip out petulantly, for a moment showing the spoiled rich boy denied a treat. The moment of childishness was quickly overtaken by cruel intelligence, and he shrugged with fake-indifference. "Who, then? A random target? Well then, pick a house, pick a year."

"Ravenclaw," said Avery.

"Fifth year," said Crabbe.

They looked to Snape, who contemplate for a moment. "Jerrod Daniels, or Erica Swift."

Malfoy gave him a sharp look. "You have the details of every student here in your head?"

Sev simply shrugged. Of course he did. If he heard it, he remembered it. It was hard for him to comprehend that other people's brains didn't work like that.

"Swift it is," said Malfoy with a shrug. Sev suspected he'd chosen to go after the girl out of spite over Snape denying him Lily. Malfoy had come to hate her quite violently in the course of their shared classes; not only was she a mudblood, a girl, and very fond of James Potter, but she consistently beat him in exams. Malfoy bore even Sev's superior brain-power with very poor grace - he certainly wouldn't tolerate it from somebody he considered pretty much sub-human.

Like many of the students from Muggle families, Erica Swift was perhaps a little more conscientious with her studies. Lucius's much-reviled 'mudbloods' were seldom any different from their classmates in their ability to cast spells - but they tended to worry much more about how they were doing. Sev happened to know that Erica and her friends would always be in the library at certain times, and that they always sat at the same table.

Malfoy's package turned out to contain numerous packets of a reddish-brown powder, almost the colour of dried blood. "What does that do?" Avery wanted to know.

"You'll see," smirked Malfoy, liberally sprinkling it over the seats around the table Snape had shown him.

Colin Crabbe's eyes went wide. "Lucius! What if somebody else sits there?" he gasped.

Malfoy grinned, with a glint in his cold grey eyes. "Ah, but that's the beauty of it. Unless they're mudbloods, it won't do anything." The others all exclaimed in delight, but Sev's brain was racing. Some kind of property they had discovered that allowed a curse to only work on mudbloods? That was trouble, serious trouble. He suspected from Malfoy's attitude that this gesture of his would be nasty, but not particularly lethal. However, once the curse existed, a sufficiently competent wizard could adapt it.

Sev thought that whoever had supplied the powder to Malfoy had made a tactical error. His 'big gesture' might send the school into a panic, but it would also alert Dumbledore and whoever he might report to; the Ministry would doubtless begin working on a counter to the 'mudblood-only' properties. It was short-sighted.

Of course, the whole Death Eater campaign was being run in a way Sev would never have chosen to. Should he plan for whatever reason to wipe out a group of people, he would do it as randomly and surreptitiously as he had handled Malfoy's schemes at Hogwarts. It was in his nature to act silently, from the shadows; apparently the same did not hold true for this Voldemort character.

Everything in the Death Eaters' agenda so far spoke of a reign of terror. The skull marks, the messages left at the scenes of crimes... the killings were not just killings, but attempts to stir up fear, mistrust, and panic. Sev strongly suspected that Voldemort was not just planning a series of terrorist attacks, but an actual campaign to set himself up as the new ruler of the wizard world. He wanted it to be so that the mere mention of names or glimpse of symbols sent wizards everywhere scurrying for cover.

And without a strong and centralised opposition, he would probably succeed. Sev, with his keen sense for people-watching, knew that the vast majority of people were nervous and afraid of change. For every wise Dumbledore or reckless James Potter, there were a hundred cowering Peter Pettigrews.

Sev did wonder to himself why he had ended up working for the opposing team. He was, after all, hardly the type to get high and mighty about right and wrong and nobility.

The best explanation he could give was that the Death Eaters' attitudes... offended his sense of logic. It was... a stupid way to do things. Inefficient. He was hardly enamoured of the Ministry's slightly wishy-washy desire to please everybody, but at least they weren't trying to skew perceptions or alter the order of things. How were you supposed to do anything if people were judged on basic labels instead of abilities? Under Malfoy's system, you worked with the premise that Crabbe was superior to Lily, and whichever angle you looked at that from, it was still insane.

For whatever reason he might have manoeuvred himself into this position, he was here now; and logic told him to stay. Cuero et al might work to get on the inside, but none of them would ever have the chance at it that he had.

So whilst the boys hung on eagerly for Erica Swift to walk into their little trap, Sev waited with them. He didn't have to pull any over-the-top expression of glee; his companions knew that his face was seldom anything but impassive. They just assumed he was feeling the same underneath.

That, Sev had discovered quickly, was the key to infiltrating any group like the Death Eaters. They automatically assumed that you would think the same as them.

In fact, as they waited, Malfoy managed to prove exactly that. "I've got a plan," he confided. "For how to get it out to the rest of the school. There's no way we can do it; we're just students. But Professor Cuero-"

"I don't trust him," Sev replied automatically. Naturally, he couldn't explain why Malfoy shouldn't go to Cuero. Though technically he was on the side of the Auror spy, now was not the time to go after Malfoy. He was still too unimportant.

"Sev, you don't trust anybody," Malfoy chided with a sharp look. "I've been watching Cuero; I think he's sympathetic to the cause."

"And if you're wrong?" he asked pointedly.

Malfoy's eyes narrowed. "I'm not a fool, Sev. I'll contact him anonymously. And we'll just see what he does about it."

Dumb. Cuero was an Auror, he had strong magic at his fingertips. Nothing Malfoy could do to stay anonymous would be unbreakable. But he couldn't reveal that knowledge without awkward questions about why he'd sat on it until now. So he said "I'm going to check him out; see what I can find out about him."

Malfoy shrugged. "Yes, you can do that." With those words, he could be satisfied that he'd changed a challenge to his authority into him giving permission to an underling. "Now stop fussing; the show's starting."

Erica and her friends came along to their usual table and sat down. They glanced across at the pack of Slytherin boys, but paid little attention to them; older students hardly ever noticed the younger, and Sev at least was a familiar sight in the school library.

At first nothing seemed to happen. Colin and Avery shifted uncomfortably in their seats; neither of them had much patience. Simon stared blankly in the general direction of the Ravenclaw table, but it was difficult to tell if he was watching or just lost inside his own head.

Sev and Malfoy were the first to notice when it started; Malfoy knew what he was looking for, and Sev was quick to pick up even tiny changes. Even Erica herself was probably unaware of it. Her hand holding the quill was beginning to shake - just judder slightly, as if she was chilled. The minor shudder rapidly spread, until her entire body was quaking.

"Erica! Are you-?" One of the boys beside her, Jed Aloysius, made a grab for her as she suddenly slid from her chair.

She hit the floor, convulsing violently now. There was a chorus of alarmed cries from her table-mates, and the rest of the students in the library came running. They crowded around to see what was going on - and who would notice if the five Slytherin boys alongside them were perhaps looking a little less surprised and much less distressed?

"She's having a fit!"

"Is she epileptic?"

"Did she just eat something?"

Nobody seemed to have a clue what to do. "Somebody get Madame Florence!" ordered Jed, kneeling beside her and pushing his bookbag under her head. "Erica! Come on girl, are you okay?" She didn't seem to be hearing him; her eyes were rolled back in her head so you could see the whites, and her skin had gone deathly pale.

Nobody moved to do Jed's bidding, and Malfoy gave Avery a shove. "You go!" he ordered, and Sev gave him a subtle nod of acknowledgement as Avery looked surprised but sped off. Jed and his friends, should they remember the Slytherin third years having been there, would also recall that one of them had a been the first to run for help. Malfoy might not be in Snape's class of genius, but he knew all about covering his tracks. He was just about able to get away with murder - a phrase, Sev suspected, which would soon, the way Malfoy was going, be less than metaphorical.

Though Sev was no expert, he didn't think that was the case here. The sustained fit looked pretty scary, but Erica didn't seem to be having trouble breathing and the convulsions weren't getting worse. He nudged Malfoy. "How long?"

Malfoy obviously knew what he was asking. "About an hour." He risked a quick smirk, feeling secure in the assumption that everyone was watching Erica. "Good, isn't it?" he murmured quietly. Malfoy was sharp, but he was also arrogant; that would likely be his downfall.

Perhaps sooner, rather than later. As Madame Florence shooed away the crowd and quickly levitated Erica to take her to the infirmary, he pulled his gang aside and told them "I've sent a anonymous note to Cuero, asking him to meet us in the Forbidden Forest at midnight. As a teacher, he has access to the Great Hall; he can get all the tables dusted with this stuff on the sly." He tapped the parcel containing the rest of the blood-red powder, and smirked. "Can you imagine the scene? We all sit down to dinner, same as usual. Then, all at once... every last damn mudblood in the room - just like Erica. I can see the panic now. We'll raise the Dark Mark over the school, and send them all a message - the day of the mudbloods is over."

"I still say you shouldn't trust Cuero," Sev warned him. Malfoy quirked an eyebrow.

"And when you can give me a reason for that, I'll listen." It suited his view of the universe to assume that he was being bold and confident whilst others were jumping at shadows.

Sev merely nodded lightly, and fixed him with a strong gaze. "Then I'll find one."

Of course, he didn't truly need to find a reason why Malfoy shouldn't trust Cuero; he had one already. The question was, what to do about giving it to him. He couldn't allow this group of novice Death Eaters to be caught out over what was, to be honest, little more than a very vicious and mean-spirited prank.

Cuero was a spy, but few people thought like Sev did. Despite the fact that none of the mudblood students would be permanently damaged by Malfoy's curse, if he knew about it he would feel compelled to stop it. And that would destroy any chance Sev had of following Malfoy to the centre of this web of conspiracy.

There were two ways he could handle this. He could spill Cuero's secret to Malfoy - or he could take the disguised Auror into his confidence.

Going to Cuero was technically the 'right' way - but he didn't like it. Cuero was a variable he had no control over. Lily and Josh Matthews already knew the truth about his association with Malfoy - and that was two people too many. An Auror was, ironically, a much worse person to entrust such a secret to; the chances of him being captured and tortured or simply fed Veritaseum were far higher.

Severus Snape lived by pragmatism and logic. There were two ways to resolve this; regardless of which choice might be 'right' or 'wrong', one greatly increased the chance that his mission would fail, and the other if anything decreased it.

He went to Malfoy.

"A spy?" Malfoy looked startled for a moment, then thoughtful. "Yes. Yes, that would make sense. That would make a lot of sense..." He turned a sharp look on Severus. "How did you find out?"

"I have my methods," he said inscrutably. He'd rather not let Malfoy know that he could brew a potion like Trustasiem - the Slytherin leader could think of entirely too many nasty ways to use it.

For a instant Malfoy looked angry - and then the expression cleared, so quickly that anybody else but Severus Snape would probably have missed it. "Yes, I do believe you do," he said with a jovial smile. He might dislike being kept out of the loop, but he was smart enough to know that Sev was invaluable to him. He had very nearly blundered directly into a tailor-made trap, and without Snape to point it out to him, he would have done so.

"What do you intend to do about Cuero?" he asked neutrally. It was too much to expect that Malfoy would be smart and leave well enough alone. His pride had been hurt the moment Cuero fooled him, and that he would never put up with.

Malfoy smiled enigmatically, enjoying having secrets of his own to keep. "Oh, don't worry about him. I'll make sure... certain interested parties find out about his loyalties." He frowned for a moment. "I suppose this means my... demonstration will have to wait for a better time; but ah, I doubt my associates will be displeased." He smiled darkly, and clapped Sev on the shoulder. "You've done me a service here today, Severus. And don't worry, it will be rewarded.

He had further cemented his own cover, at the expense of destroying another's. Logic told him that he was in the better position anyway, and that it was the intelligent thing to do.

Sev knew that he was right, but he was beginning to wonder if, when the time came, anybody else would be willing to believe that.

That night, Sev played on a hunch, and after the others dropped off he didn't get up as usual, but pretended to fall asleep. Sure enough, after a few moments the 'sleeping' Lucius Malfoy stirred in his bed and got out of it. Sev stayed facing the wall, with his eyes shut, until he heard him leave the room.

Slipping silently out of bed, he padded after Malfoy down the corridors. His spell to make him unnoticeable would only work if he was keeping still, and he had no invisibility cloak. Getting caught now would ruin everything; he stayed a long way back.

When Malfoy left via a side door and went out into the grounds, Sev didn't follow but instead retired to a window from which he could watch. He was almost amused to see the 'safe' location in which he had chosen to have a secret meeting; beneath the flailing branches of the Whomping Willow. Had it been a full moon night, he and his companion wouldn't have had nearly as much privacy as they expected.

Both Malfoy and whoever he was meeting with wore hoods pulled down over their faces. Malfoy's was not as good a disguise as he probably thought; Sev would have known him by his height and the arrogant swagger with which he walked. His companion was far more subtle, walking over to meet him with a calculated casualness which meant he probably wouldn't have been looked at twice, even hiding beneath the hood as he was. Malfoy's body language, on the other hand, practically screamed 'up to no good!'.

Sev was too far away to catch the conversation, but he could read the flow of it in Malfoy's expansive gestures as he talked. The other figure didn't seem to speak or move at all, just listened to him explain. He obviously wasn't aware of Sev watching, but he was prepared to take no chances nonetheless.

Even Sev's powers of observation could not quite identify the figure from so little data, but he quickly narrowed down his pool of suspects. This had to be the hidden Death Eater Cuero had been sent here to discover. That meant one of the staff, an observation Sev felt confident in. A seventh year might have been tall enough, but they moved completely differently to all but the most athletic of adults.

From the general height and shape of the figure compared to Malfoy, Sev could think of four teachers it might be; Professors Vitae, Fractalis, Malachite or Ephemeria. He resolved to sift through every memory he had of their actions for possible clues - but not right now. Malfoy was coming back, and he had to move quickly to get back in bed and be 'asleep' before he returned.

Professor Cuero failed to make it to Care of Magical Creatures that Thursday afternoon. Nor was he there the following week, or for the remaining five weeks of the summer term. Sev had a very strong suspicion that the Ministry of Magic would be receiving no further secret reports from him.

Cuero was dead. Sev was still in with Malfoy. And if he wasn't to find himself having made a wrong choice, he was going to have to make damn sure his mission yielded results.