Doyun returned to the stairwell three days later.
He did not plan to. The route simply presented itself as the shortest option, and he followed it without thinking. By the time he realized where he was, he had already stepped inside.
The stairwell looked unchanged.
Same lighting. Same handrails. Same faint scent of detergent that lingered near the walls.
Nothing felt wrong.
That, too, felt familiar.
People moved up and down the stairs at a steady pace. No one hurried. No one hesitated long enough to matter. The flow was smooth, almost careful.
Doyun stood near the wall and watched.
A man descending from the upper floor slowed slightly when he noticed Doyun. Not enough to be deliberate, not enough to be polite. Just enough to create a gap that hadn't existed before.
The man passed without looking back.
Doyun frowned faintly.
A woman followed a moment later. She reached the landing, paused, then shifted her grip on the handrail to the opposite side. The change was unnecessary. The railing was clean and unobstructed.
She avoided the space near Doyun without realizing she had done so.
No one stumbled.
No one slipped.
No incident occurred.
Still, the flow had changed.
Doyun moved one step to the side, testing the space. The next person adjusted their path as well, mirroring the shift without awareness. It was subtle, almost polite, like strangers unconsciously negotiating distance.
He stepped back again.
The flow relaxed.
The stairwell did not darken. It did not tighten. There was no familiar distortion, no sense of pressure building in the space itself.
Instead, the people compensated.
That unsettled him more than any pattern he had seen before.
Doyun checked the notice by the handrail out of habit. The cleaning schedule had not changed. No new warnings had been added. According to the system, nothing here required attention.
He wrote nothing.
There was no category for adjustment.
Outside, the weather was clear. The sidewalk was dry, and foot traffic was light. Doyun walked toward the subway entrance, his pace unremarkable.
At the ticket gate, a line formed briefly, then dissolved. Doyun stood at the edge of it, waiting his turn.
A man behind him shifted position and stepped into a different lane. He did not appear impatient. He did not glance at Doyun. The choice seemed arbitrary.
The woman who followed chose the same lane.
Doyun remained where he was.
The gate in front of him opened a moment later than the others. Not enough to cause delay, but enough to be noticed.
He passed through without incident.
On the platform, the yellow safety line was freshly repainted. Bright. Clear. Impossible to miss.
People stood behind it.
Except for one man, who stood just a step closer to the edge. When he noticed Doyun nearby, he moved back, aligning himself carefully with the rest of the crowd.
The adjustment was immediate.
Too immediate.
Doyun shifted his weight, placing more pressure on his back foot. The man relaxed, leaning forward again once Doyun's attention drifted.
It was not cause and effect.
It was response.
Doyun looked away, unsettled by the thought.
The train arrived. The crowd surged forward, then stabilized. Doyun boarded and found a place near the door. No one stood directly beside him. The gap was small, but consistent.
He did not force himself to fill it.
During the ride, he tried to focus on the familiar. Advertisements. Reflections in the glass. The rhythm of stops and starts.
But his attention kept drifting back to the spaces between people.
At his stop, he exited and walked toward the escalator. The steps rose smoothly, carrying passengers upward. Doyun stood still and let the line form around him.
Someone stepped behind him, then moved to the other side. Another person followed suit. The pattern repeated twice more.
Doyun stepped forward.
The line compressed again.
He exhaled slowly.
At work, no one mentioned anything unusual. The reports were clean. The numbers were stable. The system behaved exactly as it was designed to.
During lunch, Doyun sat alone by habit. When a colleague approached his table, they hesitated, glanced around, and chose another seat instead. There was no apology and no explanation.
Doyun pretended not to notice.
That evening, he took a longer route home. He avoided narrow passages and familiar shortcuts, choosing wider streets with more open space.
The effect followed him anyway.
People adjusted.
Distances shifted.
Paths curved gently away.
No one reacted strongly enough to be questioned.
That was the problem.
At home, Doyun stood by the window and watched pedestrians pass below. From this distance, the movements looked normal. Orderly. Predictable.
Only he knew where to look.
He took out his notebook and opened it to a blank page. The pen hovered for several seconds before touching the paper.
He wrote nothing.
There was nothing he could describe without naming it.
Doyun closed the notebook and set his watch beside it. The second hand remained still, indifferent to the quiet changes happening around him.
He lay down and stared at the ceiling, replaying the day not as events, but as reactions.
He had not intervened.
He had not warned anyone.
He had barely moved at all.
And yet, something had remembered him.