I learned the sound of a human cough the same way I learned the sound of a snapped bone.
Too late.
It came from the service tunnel beneath the rail depot, echoing off concrete in a way that made distance impossible to judge. Wet. Ragged. The kind that scraped the inside of the chest raw before it ever reached the air.
I froze with my hand on the ladder.
Below me, darkness breathed.
Rowan had gone down first. I heard him stop moving when the cough happened. That alone told me everything. Rowan didn't stop unless something demanded respect.
"You hear that?" he whispered.
I didn't answer. Answering meant committing to sound.
The tunnel smelled wrong. Not rot—worse. Stale heat. Old breath trapped too long in a place never meant to hold it. Someone had lived down there. Recently. Long enough for warmth to sink into concrete.
Warmth was never free.
I eased myself down the ladder rung by rung, every muscle screaming at the sudden lack of wind. The tunnel pressed in around us, walls sweating faintly where frost met trapped air. Rowan stood ten feet ahead, crowbar low, shoulders tense.
Then the coughing stopped.
Silence followed—thick, listening.
That's when I noticed the footprints.
They weren't fresh. They weren't frozen either. The snow clinging to Rowan's boots melted where he stood, dripping softly onto the concrete floor. Someone had walked this tunnel in the last few hours, long enough for their heat to linger.
Rowan exhaled through his nose. Slow. Controlled.
"We should go," he murmured.
He didn't say why. He didn't need to.
Heat meant calories. Calories meant food. Food meant people. People meant choices—and choices had a way of killing everyone involved.
I nodded once.
That was when the voice came.
Not a growl. Not a scream.
A voice.
"…don't leave."
It came from deeper in the tunnel, calm enough to hurt. A man's voice. Clear. Practiced.
Rowan's grip tightened.
I felt my stomach drop, cold flooding veins already thin with hunger.
"Please," the voice said. "I can't move much. Cold got into my legs. I've got food. Real food."
The words landed heavy.
Food was a weapon.
Rowan looked at me. I didn't need light to see the argument in his face. He was warmer than I was. Always had been. His body burned fuel like it trusted the world to provide more.
Mine never did.
"We don't know," he whispered.
"I know," I said.
That was the problem.
The silence stretched. Somewhere deeper, something shifted—slow, deliberate. Not dragging. Adjusting.
Controllers didn't rush.
"Name's Caleb," the voice continued. "Been alone three weeks. Didn't think I'd hear footsteps again."
Three weeks.
That was a long time not to starve.
Rowan swallowed. I heard it. He hated this part. Hated the math.
I stepped forward before he could stop me.
"Where's the food?" I asked.
The voice hesitated.
"Back room. Old maintenance office. Canned stuff. Some dried meat."
Dried meat meant smoke. Smoke meant fire. Fire meant warmth. Warmth meant time.
Time meant infection.
Rowan's hand closed around my sleeve. Just enough pressure to ask the question he wouldn't say out loud.
Is it worth it?
I pulled free.
The tunnel narrowed as we moved, ceiling lowering until frost kissed my hair. My breath fogged thick and heavy, bouncing back into my face. Each step forward felt like stepping deeper into a mouth.
We saw him sitting against the wall, legs stretched awkwardly in front of him.
Caleb.
He looked normal.
Too normal.
Beard rimmed with ice. Cheeks hollow. Hands shaking just enough to sell the cold. His eyes followed us carefully—not darting, not vacant. Calculating.
I felt the tightening in my chest. The sense that something was being arranged.
"Hey," Rowan said softly. "You bitten?"
Caleb laughed—a short, breathless sound.
"No. God, no. Wouldn't be talking if I was."
True.
Too true.
"Just cold," Caleb continued. "You two look like hell. Sit. Warm up a second."
Rowan hesitated.
I didn't.
That was my mistake.
The warmth hit me like a blow. Subtle, but real—heat bleeding through concrete, soaking into bones that hadn't felt comfort in weeks. My knees threatened to buckle. My hands shook harder, betraying me.
Caleb watched.
Not like prey watches predators.
Like a teacher watches students finally understand a lesson.
"You feel it, right?" he said quietly. "How good it feels to stop."
Rowan stiffened.
"Elias," he warned.
Caleb's eyes flicked to me. A smile touched his mouth.
"Elias," he repeated, tasting it. "That's a strong name."
I took a step back.
"How do you know—"
Movement.
Not from Caleb.
From behind us.
The tunnel filled with sound—soft footfalls, breath syncing unnaturally. Shapes emerged from side passages I hadn't seen, bodies half-hidden by shadow and steam. Not rushing. Not snarling.
Waiting.
Caleb didn't stand.
He didn't need to.
"You see," he said gently, "cold takes people too fast. Heat lets us choose."
Rowan swung the crowbar, catching the first shape in the jaw. Bone cracked. The sound echoed sharp and final. The body went down—but another stepped into its place seamlessly, like it had been choreographed.
Controllers.
Caleb finally rose, legs stiff but functional. The lie peeled away effortlessly.
"You could stay," he said to me, almost kindly. "You'd last longer here."
Rowan grabbed my arm, yanking me back hard enough to wrench my shoulder. We ran.
The tunnel erupted into movement behind us—not frantic, not loud. Purposeful pursuit. They didn't need speed. They knew the paths.
Heat chased us.
The ladder appeared like a miracle. Rowan went first, hauling himself up with a strength born of terror. I followed, fingers slipping on metal slick with frost and sweat.
Something grabbed my ankle.
Hands—human hands—burning hot through my boot.
I kicked, heel connecting with teeth. A scream burst free, sharp and furious. The grip loosened just enough.
Rowan hauled me up the last rung and slammed the hatch closed as something heavy struck it from below.
We didn't stop running until the wind returned.
Only then did we collapse, gasping, snow biting through soaked clothes.
Rowan laughed once. Hysterical.
"Heat," he rasped. "Heat almost killed us."
I stared back at the hatch, buried now beneath drifting snow.
"No," I said. "Heat tried to keep us."
Rowan went quiet.
That was worse.
Far below, in the dark, something waited patiently for the cold to drive us back.
And for the first time, I understood:
Winter didn't just kill people.
It trained the things that survived.