Agnes hovered closer to the forward viewport, eyes glowing faintly as she overlaid maps that didn't exist on any human chart—pressure gradients, crack density, abyssal activity, *wrongness*. The submarine drifted in the ravine's shadow, safe for the moment, engines idling like a held breath.
"…We have three viable paths," she said at last, calm and thoughtful—fully back in her caring, strategist mode.
Karl folded his arms, listening. "Lay it on me."
"Option one," Agnes continued, projecting a faint hologram of the Pacific basin.
"We stay shallow. Follow the continental shelf, minimize pressure stress, surface occasionally for recalibration."
She paused, then added gently, "High demon density. Shoreline fissures are multiplying. We'd be visible. Loud."
Karl grimaced. "So… safer for the sub, worse for *us*."
"Correct."
She flicked to the next projection.
"Option two: Deep route."
A long, curving path traced along abyssal plains and trench-adjacent zones.
"Pressure is lethal to most demons. Navigation is harder. If something goes wrong, there's no rescue, no surfacing." She glanced at him. "But it's quiet. Old. The ocean down there hasn't noticed the apocalypse yet."
Karl exhaled slowly. "That sounds like you."
A small smile tugged at her lips.
Then the third path appeared.
Agnes hesitated—just a fraction.
"Option three," she said softly.
"We investigate."
Karl's brow furrowed. "Investigate what?"
She expanded the map—highlighting an anomalous region far off the standard routes. A place where trench lines bent unnaturally, where sonar data dissolved into static.
"An ancient zone," Agnes said. "Pre-crack. Pre-demon. Pre-us."
Her voice lowered. "There are structures down there, Karl. Not Atlantean—not human. Something that *moved* when the world started breaking."
Silence filled the control room.
Karl stared at the projection. "…You didn't mention this option earlier."
"I didn't want to influence you," she admitted. "It's dangerous. Unknown. But if there's anything down there that understands what's happening to the planet—anything that knows how to survive cracks underwater—it's there."
He looked at her. Really looked.
"You're curious," he said.
"Yes," she replied. Then softer: "And cautious. If Tokyo is worse than we expect… knowledge might matter more than speed."
Karl rubbed his jaw, nanites humming faintly under his skin as he thought.
Shallow meant fast—and loud.
Deep meant safe—but blind.
Investigate meant answers… at a cost.
He glanced at Agnes. "Whichever we choose—you're with me, right?"
She didn't hesitate this time. She stepped closer, resting her hand over his chest, right above the Drive Regulator.
"Always," she said quietly. "I don't chart paths without you."
The submarine's systems waited.
The Pacific pressed in on all sides.
Karl's fingers hovered over the controls, a subtle hum of nanites running through his veins, echoing through the submarine like an electric heartbeat. Agnes's soft glow traced his movements, reading the gauges, sensors, and hull integrity with the precision of a mind that never truly rested. The unknown ancient zone wasn't on any human map. It had no charts, no name, no record of even sonar ping. And yet… it called to them both.
"I'm not gonna lie," Karl muttered, leaning forward, "this is insane. Absolutely insane."
Agnes's hand brushed his shoulder, fingers cooling but firm, grounding him. "Insanity is relative, Karl. The ocean is stranger than any demon we've faced. What we're doing is… rational, given the circumstances."
He snorted. "Rational, huh?" His eyes flicked to the viewport, where the darkness deepened, swallowing the faint bioluminescence of deep-sea flora. "Feels more like we're signing a suicide pact with a side of curiosity."
Agnes tilted her head, the faintest shimmer of amusement crossing her features. "Maybe. But I promise, if something tries to eat you, I'll eat it first."
Karl's grin was tight. "I like your priorities."
The submarine slid forward, engines muted beneath the pressure of the abyss. The water thickened in color and density, and light seemed to falter even from the vessel's high-intensity lumens. Here, depth had a taste—like iron and the faint hum of nanites, vibrating faintly against their skin. The abyss was alive in a way the surface never was.
"I can't believe this," Karl murmured, eyes tracing the faint ridge lines visible through the viewport. "I've fought a fuck-ton of demons even apocalypse-level shit. And now I'm sneaking into… whatever this is."
"Not sneaking," Agnes corrected softly. "Exploring. And learning." Her gaze lingered on him, warm, steady. "Besides… it's why we're here. If anyone can figure out the cracks—especially underwater—you can."
Karl glanced at her, letting the words sink. "I wouldn't be doing this without you."
She smiled faintly, letting the warmth of her nanite presence brush against his arm. "Never forget that. I'm not going anywhere."
The sonar pinged faintly as they approached the first anomalous fissure. The trench line curved sharply, almost unnaturally. The water seemed to ripple against an invisible current, tugging at the sub like the ocean was… aware.
"Readings?" Karl asked, tightening his grip on the controls.
"Nothing conventional," Agnes replied, voice low and measured. "No magnetic anomaly we've seen before. Pressure gradients are stable… but the composition of the water is different. Slightly heavier. Denser. There's a faint energy residue."
Karl raised an eyebrow. "Energy residue?"
"Residual Vythra patterns," she said. "Or… something similar. Not exactly what we know. Could be a civilization's leftover field. Or a defense mechanism. Either way, it's ancient."
A shiver ran down Karl's spine—not fear, not exactly, but awe. "Ancient… and still active."
Agnes floated closer, resting a hand on the console near his. "That's why we're careful. And that's why I trust you."
He looked at her, genuinely. "Good. Because trusting me is literally all you've got down here."
"Not literally," she teased, voice warm. "But close enough."
The submarine began its descent into the fissure. Pressure increased exponentially, but Karl had reinforced every external panel with nanites, twisting them into intricate latticework that could withstand almost anything the Pacific threw at them. The vessel groaned under the weight, but the hum of nanites filled the cabin like a protective heartbeat.
"Depth's climbing fast," Karl said. "I'm reading—twelve thousand meters and counting."
"Depth resistance holding steady," Agnes replied. "Hull integrity is excellent. Nanite lattice is responding perfectly."
A strange ripple ran along the viewport. Karl froze. "Did you feel that?"
Agnes's voice dropped to a whisper. "Yes… but it's not coming from the water. Something else is there."
Outside, faint shadows danced along the edges of the fissure. Long, undulating shapes, too large for normal deep-sea life, weaving in patterns almost… intelligent.
"Karl," Agnes said softly, "whatever is down there… it's watching. But we're not alone—whatever left this place is probably long gone, but the defense systems… might still be active."
Karl swallowed. "Great. Just what I needed. Ancient alien defenses under the Pacific."
She let out a soft laugh, one that didn't quite reach her eyes. "You do like this stuff. Admit it."
"Like being trapped in a potential pressure tomb? Yeah… real fun," he muttered, but his eyes never left the shadows.
Agnes floated beside him, her form flickering slightly as the nanites adjusted to the environment. "We'll go slow. Every crack, every fissure—we map it. We understand it. And I'll be here the entire time."
He let out a breath, tension easing slightly. "Yeah… yeah, I know you will."
The submarine glided deeper into the trench. The fissures widened, revealing jagged formations and collapsed stone structures that might once have been towers, platforms, or even machinery. The walls pulsed faintly with energy—unfamiliar, alive, and resonant.
"Something built this," Agnes murmured, voice reverent. "Not human. Not anything we've cataloged."
Karl felt a chill, but not of fear—of wonder. "…We've found the ruins."
"Yes," Agnes whispered, placing her hand lightly on his shoulder. "And now we learn what they were protecting… or hiding."
The abyss closed around them, ancient, silent, and watchful. For the first time in a long time, neither demon attacks nor apocalypse chaos pressed in. Only the dark, vast ocean, and the faint glow of a girl made of nanites guiding the last human she trusted into the unknown.
"Ready?" Karl asked, fingers tightening on the control stick.
Agnes smiled, her warmth steady. "Always. Let's see what secrets the deep wants to share with us."
And with that, the submarine descended further into the ancient unknown, the fissure swallowing them in shadows and whispered history, deeper than any demon had ever followed.