The submarine drifted forward into the open deep, its lights swallowed almost immediately by the surrounding black. The ravine behind them vanished into nothing, the ocean closing around the vessel as if it had never been there at all.
The sounds were no longer distant guesses.
They were closer now. Still far away, but defined. Heavy.
A low, wet groan rolled through the water, long and uneven, followed by a violent displacement of pressure that rippled outward. The submarine shuddered faintly, not from impact, but from sheer mass moving somewhere beyond sight.
Karl's jaw tightened.
"That wasn't… terrain," he said quietly.
Agnes didn't answer at first. Her projection had gone still, head tilted slightly, as if she were listening with more than ears.
Then the sonar chimed.
Not a warning. Not an alarm.
A detection.
A long, hollow pulse echoed through the control room as the sonar swept outward, its wave disappearing into the abyss and returning seconds later. The delay alone made Karl's stomach twist.
Agnes's eyes flared brighter.
"…Karl," she said.
He was already looking.
The sonar display began to resolve.
At first, it was just noise. Static and distortion, like the system was struggling to interpret something too large to classify. Then the shape started to form.
It didn't fit on the screen.
Karl leaned closer, breath shallow. "That's… that's a glitch. Right?"
Agnes didn't move. "No."
The sonar adjusted automatically, zooming out, scaling the readout again and again as the system tried to comprehend the return signal.
The shape grew.
And grew.
And kept growing.
The outline was wrong. Not smooth, not symmetrical. It looked like a mass of overlapping curves and voids, something vast and layered, stretching across the sonar grid like a continent that had learned how to move.
Karl felt cold spread through his chest.
"…That's not a demon," he said.
"No," Agnes replied softly. "That is something else."
The sonar pinged again.
This time, something new appeared.
A second return.
Tiny.
So small it almost vanished against the immensity of the first.
Karl frowned. "What's that?"
Agnes's gaze sharpened. She reached out, isolating the signal, amplifying it.
The small return moved.
Fast.
It traced tight, deliberate arcs around the larger mass, darting in and out of the sonar's edge like a living blade. Compared to the colossal entity dominating the display, it was nothing more than a speck.
An ant circling a mountain.
Except the mountain reacted.
The massive shape shifted.
A low, thunderous groan reverberated through the water again, closer now, more strained. The submarine's hull vibrated as pressure waves rolled past, strong enough to rattle loose fittings and make Karl's teeth click together.
"That thing," Karl muttered, staring at the screen, "it's reacting to the smaller one."
Agnes nodded slowly. "Yes."
Another sonar pulse.
The smaller figure surged forward, disappearing briefly into the mass of the larger return. A moment later, the enormous shape convulsed.
The sound that followed was not just a roar.
It was pain.
A deep, guttural sound tore through the water, layered with grinding pressure and the sickening churn of displaced ocean. The submarine rocked slightly, alarms flickering but not sounding.
Karl grabbed the console. "That thing just got hurt."
"Yes," Agnes said, voice low. "By something vastly smaller than it."
The sonar showed it clearly now.
The small entity wasn't fleeing.
It was attacking.
It moved with purpose, carving looping paths around the colossal form, striking and withdrawing in patterns too controlled to be random. Each pass was followed by another surge of sound, another violent shift in the larger creature's mass.
The water outside the submarine churned faintly, distant currents bending toward the struggle like iron filings drawn to a magnet.
Karl felt his pulse hammering in his ears.
"So let me get this straight," he said slowly. "There's something down here so big it barely fits on sonar… and something else is fighting it."
"Yes," Agnes replied.
"And the smaller one is winning?"
Agnes hesitated.
"…It's not losing."
Another roar rippled through the abyss, closer now, accompanied by a deep, resonant impact that felt like something massive colliding with the seafloor. Sediment bloomed in distant clouds, briefly catching the submarine's lights before vanishing again.
The smaller sonar return darted away just in time, looping back around with impossible speed.
Karl swallowed. "What is the smaller one?"
Agnes shook her head. "I don't know. But it's intelligent. Its movement is deliberate. Tactical."
"And the big one?"
Her voice dropped even further. "The big one is ancient."
The word settled heavily between them.
Ancient.
The sonar feed continued to update, the scale warping again as the larger entity shifted. Parts of it seemed to fade in and out, as if its body didn't fully obey the same physical rules as the water around it.
The smaller figure struck again.
This time, the sound that followed was different.
Not just pain.
Anger.
A deep, rolling bellow thundered through the ocean, so powerful the submarine's lights flickered. Karl felt it in his chest, a pressure that made breathing feel momentarily optional.
"That thing," he whispered, "it's aware."
Agnes looked at him. "So is the other one."
The smaller entity paused on the sonar, hovering just beyond the larger creature's reach. For a brief moment, it stopped moving entirely.
Then it changed direction.
Toward them.
Karl's blood ran cold.
"Agnes," he said, forcing calm into his voice, "tell me that's just coincidence."
She stared at the display, eyes glowing steadily, calculating faster than any human could.
"…It's not locked onto us," she said. "Not yet."
"But it noticed us."
"Yes."
The smaller return veered away again, circling back toward the colossal entity as if reconsidering priorities. The massive shape responded with another violent surge, the water around it boiling with displaced pressure.
The fight continued.
Two things that should not exist, clashing in the deepest black of the ocean, unaware or uncaring that a fragile human-made vessel was watching from the shadows.
Karl slowly eased the submarine's thrusters down, minimizing output, reducing noise to the bare minimum.
"We don't belong in that," he said quietly.
"No," Agnes agreed. "We don't."
The sonar pulsed again.
Both entities remained.
Locked in conflict.
And somewhere, deep beneath the Pacific, something impossibly old and something impossibly precise were tearing at each other in silence.
Unaware that they were no longer alone.
Or perhaps…
Very aware.