The change in strategy came from Hermione, though Harry accepted it immediately because by then he had become tired of losing ground he did not fully understand he was standing on.
For weeks they had been reacting. First to atmosphere, then to incidents, then to patterns vague enough that every attempt to name them risked sounding obsessive. Harry's instinct had been morally sound but structurally imprecise. Hermione's analysis had grown sharper, but even her best conclusions often arrived after Tom had already done whatever he meant to do. They were learning him, yes, but in the passive tense. He remained the one setting conditions.
Hermione decided she was finished with that.
The library, unsurprisingly, was where the shift began. They had chosen a table half-hidden behind taller stacks, not because either of them imagined the arrangement secret enough to evade all notice, but because physical concealment helped them think with less immediate social friction. Books were open in front of them, though none was being meaningfully read. Hermione had quills, parchment, and the expression she wore when a thought had crystallized fully enough that speaking it would feel less like speculation and more like implementation.
"We can't keep reacting after he's already done something," she said, voice low and controlled. "And we can't keep talking about him as if he's just unsettling. That doesn't mean anything."
Harry leaned forward, frustrated but listening. There had been a time early in term when Hermione's sharpened analytic tone might have sounded to him like unnecessary complication. That time had passed. Tom had cured him of underestimating precision. "So what do we do?"
Hermione had already thought this through. Of course she had.
"We stop asking what he wants in general," she said. "We start asking what he wants from specific people."
Harry frowned. "That sounds the same."
"It isn't," Hermione replied sharply, then, seeing the irritation begin in his face, corrected tone without weakening content. "You keep looking at him as if he's one problem. He isn't. He's different around different people."
That landed.
Because Harry already knew it, somewhere beneath the part of himself that still wanted villains simple enough to oppose cleanly. He thought of Neville. Of the Hufflepuff in the library. Of the Ravenclaw who had become firmer around being corrected. Of the Slytherins who seemed to settle into steadier lines when Tom was near. Of his own conversations with Tom, which had never felt like the conversations Tom had with anyone else, because Harry was being used to test moral resistance rather than self-consciousness or need.
Different around different people.
Yes.
That was true.
"So we track patterns by person," Harry said slowly.
Hermione nodded once. "And by timing. When he speaks to them, what changes afterward, whether it spreads."
Ron, who had initially insisted the entire project was absurd and had only very gradually drifted toward grudging participation, was sprawled nearby with the posture of someone wishing to preserve the right to mock an activity he had already become involved in. "So we're spying on him."
Hermione looked offended by the phrasing. "We're observing."
Ron shrugged. "That's spying with homework."
Even Harry smiled a little at that.
It was the first time in days.
The joke helped, but more importantly, the phrasing revealed something useful: they had crossed a line. The work was no longer informal unease. It had become a coordinated effort, however improvised. They were not merely talking about Tom after incidents. They were designing attention.
They divided the work almost instinctively, each role emerging from capacities already proven by the term itself. Hermione would track interactions in classes and the library, where detail mattered and where she could note exact wording or near enough to reconstruct it later. She was best at threshold moments in controlled settings—the slight correction before embarrassment hardened, the diagnostic sentence delivered when a student's internal state had become receptive but not yet fixed. Harry would watch behavior in looser spaces—corridors, meals, courtyards, stair landings—where people's emotions surfaced more quickly and where Tom's effects often spread indirectly rather than through direct contact. Harry was strongest there, in the human weather of tension and relief and instinct. Ron, who objected to formal structure on principle while somehow becoming useful within it anyway, would note rumors, complaints, social chatter, the half-formed versions of events people repeated when they thought no one especially analytic was listening.
It was, Tom would later realize, the first competent opposition assembled against him at Hogwarts.
Not because they were powerful.
Because they had finally stopped treating him as a mystery and started treating him as a method.
That made them dangerous.
The first days of their new arrangement revealed things quickly. Hermione's notes grew less interpretive and more segmented. Student, context, wording, immediate effect, delayed effect. Harry, once given a framework, became better than Hermione expected at distinguishing between direct change and distributed change. He noticed, for instance, that some students who had never spoken to Tom still began altering themselves in ways traceable through those who had. Ron proved unexpectedly valuable in one specific category: he heard what people thought they were casually saying when in fact they were repeating pressure that had already been structured elsewhere.
Most importantly, the three of them began comparing observations before conclusions. That was new. It slowed them down at first, but it also made their theory cleaner. They no longer leapt from single event to total interpretation. They watched for repetition. Hermione, who preferred exactness anyway, appreciated this. Harry, who disliked feeling one move behind, appreciated even more that structure gave his instincts something to attach to.
Tom noticed the coordination within two days.
Not the content. Not immediately. But the rhythm. Harry and Hermione now watched him differently—not separately, not with their old independent patterns of attention, but with overlap. Hermione's questions to other students became oddly specific in the aftermath of practical classes. Harry's gaze stopped landing on Tom only at the moment of visible disturbance and began appearing in the quieter intervals before and after. Ron, most tellingly, now listened before dismissing.
Interesting.
Tom did not alter his behavior.
Not yet.
Any abrupt change would confirm too much. If the trio had reached competence, the worst response would be to reward it with visible defensive adaptation. That would teach them too quickly. Better to continue as before while mapping the rhythm of their attention in return. If they intended to study him properly, then their study itself could become material.
Harry, for his part, felt the shift in himself almost immediately. Working with Hermione this way altered him. He became less eager to confront and more willing to watch one additional day before acting. It was not that he had become calmer in any general sense; he still flared quickly when something struck him as wrong. But now the flares had somewhere to go afterward besides frustration. He could compare them against Hermione's notes, against Ron's overheard fragments, against patterns.
The effect on Hermione was subtler but just as real. She had carried much of the burden privately before, partly because precision isolated her and partly because she did not trust unstructured concern. Now, with Harry and Ron contributing differently but genuinely, the burden changed shape. She no longer had to prove to herself first that every impression was worth recording. She could let the structure of the group test it instead.
Ron complained constantly about the "system" while continuing to use it.
That too became part of the structure.
One evening, after comparing several days' worth of observations, Hermione sat back and said, "He noticed."
Harry looked up immediately. "What?"
"That we're coordinated."
Ron muttered, "Brilliant."
Harry's face tightened, but not with surprise. More with recognition. "How can you tell?"
Hermione flipped back through her notes. "Because he's not changing anything obvious, which means he knows sudden changes would be too revealing. But he's started watching in the gaps."
Ron frowned. "The gaps?"
"The moments before and after things matter," Harry said, before Hermione could answer. "When he's not talking."
Hermione nodded. "Exactly."
That realization should have been discouraging. In one sense, it was. It meant Tom was now studying them studying him. Their observation was no longer passive in his eyes. It had become an environmental variable. But there was another side to it, one Harry felt before he could fully explain it and Hermione put into words a moment later.
"That means we matter now," she said.
Ron blinked. "I'm not sure that's comforting."
"It isn't," Hermione replied. "But it means we're no longer irrelevant to the structure."
Harry looked into the fire, thinking. Tom had spent the whole term making others react to him, teaching them his shape while remaining one step ahead of their attempts to define it. The idea that he now had to account for them—not fear them, perhaps, but account for them—offered something Harry had lacked for too long.
Leverage.
Small leverage.
Fragile leverage.
But real.
Across the castle, Tom sat in the Slytherin common room with a book open and three distinct layers of attention running at once: the conversation nearest him, the broader room, and the pattern of how often certain names, tensions, and repeated complaints surfaced through others in ways not fully organic anymore. Harry, Hermione, and even Ron had introduced a new element into the school's atmosphere. Not because they were exposing him publicly. They were not yet capable of that. But because they had stopped diffusing their concern separately and begun converting it into shared method.
That made them more dangerous.
It also made them more legible.
And legibility, Tom thought, was one of the few gifts opponents ever offered voluntarily.