Disclaimer: J.K. Rowling created and owns Hogwarts, Severus Snape, and almost everything else in this story - for which I will be forever jealous.
Author's Note: The sequel to CoS: Fifth Columnist.
Platform nine and three-quarters grew suddenly quiet as Severus Snape stepped onto the platform. Eyes flicked from him to the four Gryffindor boys clustered at the other end.
Ignoring the weight of the students' collective gaze, Sev slid through the crowd and joined a different group. A moment later, the hum of conversation warily resumed.
"Severus," said Malfoy coolly, sharp grey eyes betraying no hint of whether Sev's presence filled him with distaste or left him unmoved.
"Lucius." Sev didn't bother to acknowledge the other boys' presence, but as always, he missed little.
In the upper end of their teenage years now, they weren't quite boys any longer. Colin Crabbe, never quite small and dainty, had achieved the rough size and proportions of a young gorilla. Nick Avery's too-pretty features had firmed into the face of a young god, neatly masking the darkness beneath. And Simon Lestrange... Simon had grown older, but his puffy features and deep green eyes still looked disturbingly childish. Childish not in the sense of sweet and innocent, but rather in the lack of comprehension of adult concepts like right and wrong or morality.
Beside them were two younger, but no less familiar faces: Graham Goyle and Alex Nott. In the year below, Nott and Goyle practically worshipped Malfoy, and had been drawn deeper into his confidence as time went on.
Sev, by contrast, had teetered dangerously on the edge of being pushed out. Malfoy's jealousy of his intelligence, coupled with resentment from when Sev had been made a Prefect and he was passed over, had resulted in a definite growing apart.
In a perfect world, growing apart from Lucius Malfoy would hardly be a tragedy, but Sev happened to have very good reasons for needing to be in with him. Malfoy was his only link to the Death Eaters, a highly dangerous organisation who had at least one agent on the Hogwarts staff. Sev, recognising that nobody else would have such an opportunity - or the skill to pull it off - had appointed himself counterspy, and worked from the very start to get as deeply rooted in the Death Eater organisation as his skills would allow.
It had taken a very risky venture indeed at the end of last year to make the Death Eaters believe he would do anything for them. By putting his own life in danger and making it all the Gryffindors' fault, he had made a very convincing case for his 'hatred' of the current order and all it represented.
Dumbledore, never slowest on the uptake, had got in on the act, deliberately being light on punishment to make Snape's resentment all the more justified. In return, he had set Sev the task of designing him a foolproof trap to find the traitor on the staff.
Sev had spent much of his holidays in contemplation, and as he and the other Slytherins rode the train to Hogwarts, he turned the ideas over in his head once again.
Whether Snape was hugely more intelligent than those around was perhaps a matter of opinion, but certainly where he differed from others was his ability to polish ideas to perfection. He had a great skill for reading people, and coupled with relentless logic it allowed him to play those surrounding him perfectly. Sev might act quickly, but never impulsively. Nothing he ever did was completely uncalculated.
The shift between impassiveness and howling anger he managed to portray might seem implausible, but people wanted to believe it. It made them feel more comfortable to believe that his passions could rule him, like anybody else.
Sev had passions, in his own quiet way. But he kept them on the inside.
Anybody watching him on the train would have seen simply a young man, quieter than his rowdy companions, staring out of the window and seeming in a world of his own. They wouldn't have known that he was plotting deception, and never missing a word of the conversation around him as he did it.
The platform on the Hogwarts end was rowdier than in previous years. The Death Eaters had been lying low, and there had been no disasters other than Snape's brush with death - dismissed by most of the school as a schoolboy prank, just as he'd intended. When nothing went wrong for a while, people started to believe that the badness must have gone away.
People were stupid.
Sev tuned out the sorting song and the usual celebrations, but he paid more attention to Dumbledore's welcoming speech.
"As you all no doubt know," he was saying, "times have been somewhat... troubled, of late. However, even in these dark days, there is always room for hope and celebration. With that in mind, I have decided that this year we will hold a summer festival."
There were whoops and cheers from everybody but the professionally unimpressed Slytherins.
"What kind of a festival?" called James Potter over the general noise. Dumbledore smiled at him.
"Well, that would be up to you. We'll be asking for ideas from the students for the kind of celebration you'd want... within reason," he added, with a pointed look at the rowdy Gryffindor table. He smiled again, and clapped his hands. "We'll discuss this again later in the year, but for now, it's time for me to stop talking, so... eat, drink, and be merry!"
"For tomorrow, you die," Sev completed quietly. Beside him, Malfoy snickered.
Sev knew a summons from Dumbledore was coming, but the headmaster was too subtle to haul him in immediately. It was several weeks before Professor Malachite snagged him at the end of class and said "Ah, Severus. Professor Dumbledore asked if you'd go and see him at the end of today, if you can find the time."
Malfoy glowered suspiciously, and Avery said "Hey, Sev, what did you do this time?"
Sev made a point of rolling his eyes in a long-suffering manner. "No doubt I'm being blamed for something house Gryffindor did, yet again."
Beside him, Malachite's mouth compressed into a tight line. The Defence Against the Dark Arts teacher was fiercely proud of his ties to house Slytherin, and furious with the way his students were always tarred with the same brush. Considering the current crop of Slytherin bad apples, he was very much fighting a losing battle.
Sev made his way down to the concealed entrance to Dumbledore's office - it opened before he needed to announce his presence. He stepped inside, and made his way to where Dumbledore was waiting at his desk.
"Headmaster," he said with a nod.
"Severus." The headmaster smiled faintly. "Settling in well?"
It was hard to tell if he was being ironic or serious. Sev shrugged. "Well enough."
Dumbledore leaned towards him. "Have you given any thought to what we discussed last summer?"
"Of course," he said.
"And do you have a plan?"
Instead of pressing him for details, Dumbledore said simply "What do you need?"
"Something they want," he replied.
He shrugged slightly. "It really doesn't matter. They just have to want it."
Dumbledore smiled faintly. "I'm sure I'll be able to find something. We can't have a trap without bait, now can we?" He frowned slightly. "Bait that they won't get hold of, or bait that they will?"
"Better always to assume the worst, isn't it?" Sev pointed out.
The headmaster looked at him over his glasses. "Better for your plans, perhaps. Not so good for the way you think." Sev couldn't have given him any answer that would have satisfied, nor was he inclined to, so there was a brief silence. Dumbledore shuffled papers on his desk. "I'll speak to you again when I have something for you."
Sev nodded, and got up to leave. On his way, he hesitated, and then turned back. "Oh, and by the way. You're calling together the sixth years who are ex-Prefects to help organise the festival."
Dumbledore looked up at him for a moment, and then nodded. Sev left.
Malfoy cornered him when he got back to the dorms. "What was that about?" he demanded.
"Parties," Sev said, with just the right note of disdain.
Malfoy looked as sceptical as the idea of Sev Snape being involved in a party deserved. "You? Dumbledore wanted to talk to you about parties?"
Sev looked mildly irritated. "This stupid summer festival. He wants last year's Prefects to help organise it."
Malfoy snorted darkly. "Yet again, I give thanks they passed me over," he said, rolling his eyes. Sev knew for a fact that wasn't true. As unimpressed as he acted, Malfoy had desperately wanted the Prefect honours for himself. It didn't matter to him that the position belonged to an order he detested - it represented power over others, and Lucius Malfoy considered power his birthright.
"Something else you might be interested in," Sev told him.
"Interested? In this ridiculous festival idea of theirs?" Malfoy said scathingly.
"Not the festival." He leaned in closer, though there was nobody else in the dorms to hear. "Dumbledore was talking about something... a package, from the Ministry of Magic. I don't know what it is, but it sounds like something important."
Malfoy nodded wisely. "Really? Interesting, Severus. Very interesting." He stood up. "I think perhaps I'll... despatch that little titbit through certain channels." He smiled mockingly at Snape, and left.
Malfoy enjoyed holding his superior knowledge over him - as if to say 'you may be smart, but I know who the Death Eater is, and you don't'. Sev was untroubled. Soon enough, that would be changing.
'Soon', perhaps, was not the same for Severus Snape as it might be for another boy his age. Whilst his classmates all thought in terms of the here and now, it never bothered Snape to look to the long term; after all, that was how he'd got into the spying game in the first place.
The unfortunate side effect of his cover-up about ex-Prefects helping with the festival was that they had to well, actually do it. Fortunately the houses were mostly arranging their own events of the festivities, so that meant minimal contact with his new 'deadly enemy' James Potter.
The festival was to be held at the end of the summer term, and involve the entire school. Dumbledore wanted nobody to be left out, leading to complaints that he was asking for trouble - which, of course, he was. The more chaotic the festival, the better the opportunity for the Death Eater to make a move.
With their new, more advanced lessons as they moved up from OWL to NEWT level, the sixth years were heavily involved in various projects for unveiling in the summer. Sev, naturally, had drawn OWL results as close to perfect as he chose to get away with - deliberately falling just a handful of points behind Potter to let the 'resentment' simmer a little more.
In the upper years, things were more flexible. Although the sixth form at Hogwarts was still more a school than a college, the students had a little more freedom, and were given more time off to study, although that was seldom what that time was used for.
The next part of Snape and Dumbledore's plan was called into play when the headmaster called a meeting of staff and festival-organisers. They all filed in to the meeting room in various states of enthusiasm. Sev kept a look of resigned boredom throughout the quibbling over various tasks and events, not a great stretch of his acting abilities.
"And now, on a more serious note," Dumbledore added as the Prefects were dismissed, "I have a few other tasks that need taking care of. Potter, Snape, if you'd like to wait behind for a moment?"
They both lingered, shooting wary glances at each other. Lily stayed behind as well, waiting for James.
"Come here, boys," said Dumbledore fondly. He addressed both them and the gathered staff. "As you are no doubt aware, messers Potter and Snape hold the distinction of some of the best test scores this school has seen in recent years."
Professors Vitae and Malachite both grinned triumphantly, happy to take credit for achievements that were more likely due to the students in question than the guidance they had received.
Dumbledore smiled at the two boys.
"It happens that I've been working with the Ministry of Magic over the summer. With the worries about safety that we've seen in recent year, they've been testing a number of new devices. However, as any good inventor knows, no device has been truly tried under adverse conditions until an agile young mind has been given the chance to take it apart and see how it works." There were a few acknowledging smirks from the teachers.
"James, I'd like you to take a look at a new device called a Pocket Sneakoscope. It's based on the kind of dishonesty detectors that the Ministry use, but in a small, portable form and available for the general public. They've tested it in their laboratories of course, but it needs some genuinely sneaky intentions to work properly... assuming, of course, you think you can find any students who might be trying to get away with something..."
James grinned, and then shot a pointed look at Snape. "I'm sure I can find one or two, Professor." Malachite scowled darkly at him.
"And what about me, Professor?" Snape spoke up.
"Ah, yes, Severus." For somebody who seemed so twinkly-eyed and honest, Dumbledore certainly did a masterful impression of having quite absent-mindedly forgotten the main purpose of this charade. "You, young Mr. Snape, are going to be road-testing a prototype of an extremely powerful device called a Foe-Glass."
"What's that?" asked James with a frown, obviously trying to decide whether or not to be jealous.
"The Foe-Glass, once it's fully operational, will be an invaluable aid to Aurors in the fight against evil. It allows the user to see the face of their enemies; the more sharply defined the focus, the more immediate the danger. It needs a great deal of fine-tuning yet, but once it has been perfected, finding the Death Eaters amongst our own will suddenly become a far, far easier task."
The murmur of interest that rippled through the staff was such that there was no way to tell which of them was exclaiming for a reason that had little to do with pleasure.
"That sounds... more interesting than mine," said James, not quite able to bury an edge of petulance.
"No doubt House Slytherin find it easier to test a device for finding enemies than most," spoke up Professor Vitae silkily. Beside her, Professor Malachite sneered.
Dumbledore clapped his hands together, pretending not to notice what was going on beside him. "I have the devices in my office, at present. They'll be moved to some place where they can be studied as soon as the arrangements for security are quite finished."
Sev didn't need to ask when that would be; after all, it was he himself who would be developing the security system. A system that he would be oh-so-helpfully instructing the Death Eaters in how to breach...