Tom realized they were getting closer when Hermione Granger stopped looking puzzled and started looking prepared.
Puzzlement, even highly intelligent puzzlement, was not especially dangerous. It consumed attention inwardly. It produced questions, notes, theories, and those were all useful in their way because they kept the observer focused on interpretation rather than interruption. Preparation was different. Preparation implied the observer had crossed from understanding into timing. It meant they were no longer merely trying to describe the mechanism. They were beginning to act on it.
He noticed the change in Transfiguration, which was fitting. Transfiguration rewarded precision more visibly than most first-year subjects. It punished overconfidence, carelessness, and uncontrolled emotion with equal indifference, and because of that the classroom produced a clear range of threshold states for anyone patient enough to observe them. Tom had found it useful for weeks. Students became briefly transparent there in the moments between failure and correction, between embarrassment and adaptation. Hermione had noticed this too. He knew she had. But until recently she had still remained half a step behind the threshold, identifying the pattern after it had passed through someone else.
That morning, she arrived ready.
The class itself began ordinarily enough. Professor McGonagall moved between desks with her usual controlled severity, offering praise so sparingly that when it came it functioned almost like a public event. The room carried the quiet pressure particular to her lessons, where every student believed—correctly—that competence would be respected and sloppiness would not. Tom worked with his usual measured efficiency, not especially fast, not especially slow, allowing his competence to settle into the room at exactly the level he preferred: undeniable, but not showy enough to become the lesson.
A first-year Ravenclaw several stations away made a small, familiar error with wand angle while attempting a refinement charm. It was not the sort of mistake that would ruin the exercise outright. That was what made it useful. If the error had been catastrophic, McGonagall would have corrected it herself, and the threshold would have belonged to institutional authority rather than to the student's self-relation. This error was better than that. It produced repeated slight failure. Enough to sting. Not enough to invite rescue.
Tom noticed at once.
So did Hermione.
That was new in itself—not that she noticed, but that Tom noticed her noticing with equal immediacy. Her attention did not flicker with vague concern the way it once had. It locked onto the Ravenclaw with specificity. She had identified the state as relevant. Tom saw it and, in the same moment, understood the danger: she was no longer looking for aftermath. She was looking for the opening.
Under ordinary conditions, he would have waited a little longer. The Ravenclaw's frustration had begun but had not yet settled into the shape most receptive to precision. The boy was still in the first phase—annoyed, self-conscious, trying to force technique through discomfort. Another failed attempt or two, another glance at the better-performing students nearby, another inch of tightening in the shoulders, and the threshold would sharpen.
Hermione moved first.
Not by much.
Just enough.
She crossed the small distance with perfect ordinary plausibility, as though merely adjusting her own position or returning a tool. Then, in a tone pitched to be useful rather than superior, she said, "Your wrist is collapsing inward."
The correction was accurate.
More importantly, it was timed correctly.
Tom felt the shape of the interruption immediately.
Interesting.
The Ravenclaw blinked, adjusted, tried again, and this time the charm held. The visible result was modest—an incremental improvement, the kind of thing teachers saw constantly and classmates mostly forgot. But the internal result was more important. Relief came before destabilization. The student improved in a state of gratitude rather than sharpened self-consciousness. The correction had not merely preempted Tom's intervention. It had changed the emotional texture of the moment entirely.
Hermione did not look at Tom afterward.
That told him more than if she had.
If she had looked, it would have meant she wanted confirmation, victory, acknowledgment—something. Not looking meant she already understood what she had done and preferred not to expose the understanding. She was protecting the structure of her counter-move by refusing to mark it socially.
That was far more inconvenient.
Tom did nothing outwardly. He continued with the lesson. He answered when McGonagall called on him. He adjusted his own work with the same unbroken calm as always and left the classroom at the appropriate time without hesitation or visible reaction. But inside, he had already begun revising.
Counter-intervention changed the structure.
If Harry and Hermione were no longer merely observing but beginning to preempt, then his existing method would narrow too quickly. It was not enough now to identify thresholds in others. He would have to identify thresholds while also calculating whether Harry or Hermione had identified them too. That meant timing alone could no longer guarantee efficiency. A new layer of complexity had entered the environment.
He did not resent Hermione for this.
In some respects he appreciated it.
Resistance that improved the game was better than resistance that merely objected. Harry's moral opposition, while structurally valuable in other ways, rarely forced elegance from him. It forced containment, reframing, indirect use. Hermione did something more useful. She altered the problem itself. By countering his timing rather than simply condemning his purpose, she required adaptation.
That was worthy of attention.
At lunch, Tom watched more than he usually needed to. Not visibly, not enough for anyone but perhaps Dumbledore to notice a difference, but with a deeper inward allocation of thought. Hermione and Harry sat together as they often did now, but the quality of their coordination had changed. Hermione spoke first; Harry listened with his whole attention, which meant they were comparing something that had happened recently and specifically. Ron looked mildly irritated by whatever system he was being made part of and yet remained present, which in him functioned as a kind of unwilling commitment.
Tom mapped possibilities.
If Hermione could now intervene at threshold with accuracy, the next phase could no longer rely on single openings that an external observer might preempt cleanly. He would need layered conditions—situations in which there was no obvious singular moment to step in without exposing the counter-observer's own pattern of attention. He would need events distributed across multiple students, or across time, or structured so that one accurate correction merely diverted the visible branch while two quieter consequences went untouched.
Inconvenient.
But manageable.
That afternoon, he entered the learning space with an unusual stillness in him, and Andros noticed immediately. Over time the ancient wizard had learned that stillness could indicate many things in Tom—satisfaction, calculation, containment, danger, or some mixture of all four.
"You've met resistance," Andros said.
Tom almost smiled. "Competent resistance."
Andros looked relieved in a way he likely had not intended to show. It was not joy, exactly, but something akin to moral exhalation. The sight irritated Tom only because it was honest.
"Good," Andros said.
Tom's eyes flicked toward him. "Why?"
"Because unchecked methods grow arrogant."
Tom let that sit between them. The statement was not wrong. That was part of what made it annoying. Arrogance, in Tom's experience, did not usually arrive as visible boasting. It arrived as simplification. As the assumption that what had worked several times would continue working unchanged under altered conditions.
"Perhaps," he said.
Andros held his gaze. "And perhaps you are closer to unchecked than you should be."
Tom did not answer.
What answer would there have been? That Andros was morally sentimental? He already knew that. That resistance sharpened him? Also true. That Hermione's interference had not produced any remorse, only revision? True again. The old wizard did not need those admissions. He needed Tom to become self-suspicious in a moral register Tom did not share.
But Tom did adjust.
Not morally.
Structurally.
That mattered. If one could not be corrected toward conscience, one could still be corrected toward subtlety. And subtlety, while not virtue, often produced fewer visible harms in the immediate term than unchecked directness would have.
Back in the waking world, his behavior remained outwardly unchanged for the next few days, but the internal alterations were already active. He stopped favoring single, clean interventions in classrooms where Hermione could easily identify the threshold. He let some opportunities pass entirely. He introduced mild pressure in one context so that the true threshold would arrive later in another, less visible one. He began preferring situations where Harry's and Hermione's attentions could be divided—meals, corridor transitions, library traffic, the aftermath of rumors rather than the visible center of them.
This was the first time anyone at Hogwarts had forced him to improve the method.
Hermione, for her part, felt the success more as confirmation than triumph. She told Harry about the Ravenclaw afterward in a tone deliberately flatter than the moment had felt from inside it.
"I got there first," she said.
Harry looked up sharply. "Did it work?"
"Yes."
That single word carried more within it than either of them named immediately. It meant Tom's method was interruptible. It meant threshold recognition, once understood, could be countered. It meant they were no longer only describing the system from within. They were beginning, however slightly, to alter it.
Harry's immediate response was not celebration.
"He noticed," he said.
Hermione hesitated, then nodded. "Yes."
"How can you tell?"
"Because he didn't do anything after."
Harry understood that at once. Tom's lack of visible response was itself a response. It meant he had recognized the interference and chosen not to contest it publicly, which in turn meant he was adapting rather than reacting. That made the victory real and incomplete at the same time.
Ron, when they explained it to him later in rougher terms, looked between them and said, "Brilliant. So now he knows you know."
Neither Harry nor Hermione answered.
Because that was exactly the problem.
That night, Tom lay awake longer than usual. Not from agitation, but from revision. He reviewed his recent sequences with increasing care and found what he had half-expected to find: too much reliance on visible thresholds, too much confidence in the uniqueness of his timing, too much trust that observers would remain one explanatory step behind implementation. Hermione's move had not disproven the method. It had exposed a simplification within it.
Good.
The next phase, he thought, would require greater subtlety.
He had outgrown simple calibration.
Now he would need layered effects.
The classroom was empty.
That made it honest.
No witnesses. No interpretations. No secondary meaning spreading outward through the school. Just two people, and the space between them.
Harry raised his wand first.
Tom allowed it.
"Expelliarmus!"
Tom deflected—but not by force.
He angled his wand just enough that the spell dispersed before fully forming impact, its energy slipping sideways into the wall behind him.
"You're still doing it," Tom said.
Harry didn't respond.
He cast again.
Faster.
Better aligned.
Tom stepped instead of blocking.
The spell passed where he had been.
Harry noticed.
That was new.
He waited.
That was newer.
Tom's mouth shifted—almost a smile.
"Now you don't know when to act."
Harry ignored him.
Or tried to.
He cast again.
This time—
Different.
Not faster.
Not stronger.
Placed.
Tom raised his wand—
Too late to avoid.
He blocked.
But the force pushed him half a step back.
Minimal.
But real.
Harry saw it.
That was the opening.
He stepped forward—not casting immediately, but closing space.
Tom adjusted instantly.
A flick of the wand—
A pressure spell—not visible, not dramatic, just enough to disrupt Harry's next motion.
Harry corrected—
But slower now.
The advantage was gone.
Silence.
They stood still.
Wands raised.
Neither committing.
Because now both understood:
The next move would matter.
Too much.
Tom lowered his wand first.
Not conceding.
Ending.
"Almost," he said.
Harry didn't answer.
But he didn't lower his wand immediately either.
And that was the real result of the duel.
Not victory.
Not defeat.
But the fact that for the first time—
Tom had needed to adjust.