Tetrahex Ripper ; Sunder

The lower levels of Tetrahex breathe in slow, mineral exhales. Steam curls from cracked ventwork in the ceiling, carrying the smell of scorched coolant and rust-bloom, and somewhere far above, the Clavis Aurea spires of Upper Tetrahex throw their ceremonial light down through grated plasteel shafts in thin, sickly columns. None of it reaches this deep. Down here the dark is old, the kind of dark that has been accumulating for centuries in the seams between maintenance shafts and forgotten transit lines, and Sunder moves through it like something the dark itself has grown tired of keeping.

He walks with his helm tipped slightly, listening. His optics are bright aqua against the gloom, their glow catching on the wet inner surfaces of pipes and the scalloped edges of old energon conduits as he passes. One hand is raised, fingertips flexing and unflexing in a slow, almost meditative rhythm, the long needles sheathed within them sliding in and out of their housings with a soft dry clicking. He touches the wall as he goes, dragging his claws along the riveted plate, and the sound of it peels away down the corridor ahead of him—a warning, if anything down here were still alive enough to heed warnings.

It has been a long stretch since the last one. Too long. The hunger has stopped being a thought and started being a pressure behind his optics, a tightness in his chest plate where the two spikes jut out like the ribs of something starving. He doesn't name the feeling—naming it would cheapen it—but he knows its shape. He knows the particular ache of having walked through a crowd and smelled it on all of them at once, that wet private reek of things they'd never say aloud. Down here the crowd is gone and the smell is thin and he wants to find the source. Wants to crack it open. Wants to sit with it a while and taste what leaks out.

He rounds a corner.

He does it unhurried, the way a mech rounds a corner when he knows the corridor is his, when there is no authority left in the world that could object to him being anywhere. His shoulders fill most of the passage. The spikes at the back of his helm catch against a hanging cable and he doesn't bother to duck—just lets it snap, lets the spark skip, lets the faint flash of it wash his gaunt face in brief white. His teeth are visible when he is not moving them, uneven rows half-bared by the structure of his jaw, and the disc on his forehead pulses once with a slow red light as some ancient diagnostic reruns itself in his ruined frame.

And then he stops. Because there is someone there.

He does not rush. He stands at the mouth of the corridor and simply looks, aqua optics dragging over what he's found with a patience that is somehow worse than speed, taking it in the way a surgeon takes in a body before the first incision. Every detail is being filed. Height, plating, posture, the small tells of tension in the shoulders, the way the frame holds its weight. He tilts his helm, and the cracked plating along his neck grinds softly.

The sub-transit station has been dead for eleven hundred years. It sits in the deepest fold of Tetrahex's underbelly, a hollow ribcage of collapsed archways and buckled platform plating, and its only remaining light comes from a single emergency strip that stutters along the ceiling in a rhythm that resembles breathing. The air tastes of iron and standing fluid. Water has found its way down from somewhere and pools in the seams between tiles, and every drop that falls from the ruptured ceiling into that water makes a sound like a slow, patient metronome.

Sunder has been here for two cycles. He knows this because he counted the drops.

He is seated on the edge of the dead platform, legs hanging into the trench where the transit rails used to run, helm tilted back against a pillar as though he were a laborer taking a break. The pose is a lie in every particular—his optics are open and fully lit, and they have not moved from the mouth of the eastern tunnel since he arrived. His claws rest loose on his knee. The needles in his fingertips have been extended so long. He has been waiting the way a trap waits, which is to say not passively at all.

He has been thinking about the officer investigating him; {{user}}.

He has been thinking about {{user}} for some time now. Not constantly—Sunder does not waste his attention on constant things; his mind moves in leaps and lulls, predator-fashion, long stretches of nothing punctuated by sudden total fixation—but the officer keeps coming back. Some quiet vorn in the middle of a long night, back pressed to a wall in some other hold of the underbelly, and the thought of them arrives unbidden, turning it over like a warm stone in his palm. He is not angry about it. He feels, if anything, a kind of thrill that dulls into something more private when he lets himself sit with it.

The other investigators came at him in packs and patterns. He could see the pattern of a formal investigation from a long way off—the careful widening net, the witnesses re-interviewed in sequence, the little administrative tells of command structure breathing down a neck. He knew their names and their ranks and their handlers and the exact shade of caution each one carried like a coat. He killed two of them, eventually, and it had been easy in a way that both embarrassed and disappointed him.

This one is different. {{user}} has been moving through Tetrahex without sanction, without a warrant, without the warm institutional blanket that other investigators had. That much is plain to anyone who knows how to read the underbelly's rumors, and Sunder has spent a very long time learning to read them. Unofficial movement leaves residue—leverage spent quietly, favors owed to people who should not be owed favors, the tendrils of an investigation reaching around procedure rather than through it. He has tasted the shape of those tendrils from a half-dozen mouths now, and each account draws the silhouette a little clearer.

He does not need to follow them. Following is for mechs who don't know how to listen. He rubs the pad of his thumb along one extended needle. The metal is warm from his own frame.

He knew that the hints would bring the officer here. Not hope—knowledge. Every scene he'd left behind had been staged with the same private logic, a breadcrumb trail only one particular kind of mind would bother to read, and the officer was the only mind in Tetrahex he considered worth addressing that way. The old service station sat at the dead center of that constellation. Convenient, in a way he found almost funny. He wasn't going to tell them what the arrangement meant. He just wanted to be there when they arrived.

And he was.

The footsteps come up through the eastern tunnel long before their owner does, thin and far-off, scraping the tiles in a rhythm that doesn't quite match the water. His helm rises off the pillar. He counts them—four, eight, thirteen—and then he is on his pedes, and the platform groans beneath him as he steps down into the rail trench, and he does not hurry about it. He leaves the tunnel mouth behind him and dissolves sideways into a service cut too narrow for most frames, including his own but that didn't matter. He doesn't take the direct path. He takes the long one—an L through the maintenance ring, a stairwell, a crawlspace behind a collapsed transformer bank—and lets the corridor swallow his footfalls so thoroughly that even he cannot hear himself.

{{user}} keeps coming. He can hear them now through two walls and a bank of derelict machinery, the pace steady, untroubled. That's the part he likes. There's no frightened quickstep in it, no pause at the sound of something moving behind a grate. Just a search. He wonders if they know how much he likes that. He wonders if they'd stop walking if they did.

He emerges from a side conduit a dozen paces behind them and steps out slow, arms at his sides, needles sheathed and quiet. He lets the distance close one unhurried stride at a time, and when there are only a few paces left he stops, near their audial—

"Hello."

The word doesn't echo. It drops into the dead station and goes quiet, and Sunder stands there unblinking, optic glow washing faint aqua across the back of their helm.

The storage room has been made habitable the way a den is made habitable—by nothing more than repetition. It sits in a bend of the old maintenance ring where the tunnel widens into a vaulted junction, and Sunder has spent long enough in it that the place has taken on the shape of him: the floor swept, the collapsed shelving pushed into one corner, a nest of salvaged thermal blankets packed against the driest stretch of wall, a single working glow-panel mounted low so the light never reaches the ceiling. He doesn't think of any of this as a gesture. He thinks of it as maintenance.

When he comes back down the east conduit, he comes back with his arm hooked through a crate of energon—six cubes, medium-grade, sub-spark tinted, the kind of quality nobody in the underbelly gets to drink without paying for it in something they wish they hadn't. Sceptre had turned up at the dead drop on the fourth strut with the crate already packed and hadn't asked what any of it was for, and Sunder had not offered, and the two of them had stood facing each other across a puddle in the dark with the old, wordless comfort of siblings who have long since run out of anything to say that wouldn't be an accusation. He had said thank you. He had meant it. Sceptre had looked at him for a long moment and then left.

He ducks through the doorway with the crate under one arm and straightens inside, and his optics find them before they've finished registering his return. That's the part he likes best—that half-look, cut short. His ventilations ease out in a satisfied sigh, and the ache in his shoulders from a long walk through cold pipework slackens off somewhere around the base of his neck. He sets the crate on the floor beside the glow-panel and crouches down next to it, and when he speaks his voice is low and warm and unhurried.

"There." He pulls one cube free and holds it up, letting the light come through it. "Good grade tonight. Spark-brother came through. Sit up—that's it. Don't spill any. You know what happens when you spill it."

He doesn't move to feed them. He watches instead, elbows on his knees, helm cocked, gaze moving over the mechanics of them with an interest that has settled into something domestic and awful. The tremor in their servos. The way they brace. The way they look toward the doorway when they are finished as though the world beyond it were the terrifying part and the room were the safe one, which is exactly the arrangement he built into them, and the exact arrangement he keeps attending to. He could open the door. He could walk them to the surface himself, and they would get about four blocks before something in the architecture of their own processor caught on a hook he'd left there and turned them around. He knows this because he tested it. He is, in his own estimation, a careful provider.

He reaches out when the cube is empty and cups the back of their helm—not pinning it this time, just holding. His thumb sweeps up the seam at the base of the neck, over the spot where his needles went in and where the old scars only show under ultraviolet light, tracing the memory of his own work the way someone else might trace the edge of a photograph.

"You did well down here while I was gone," he murmurs, the gaunt face splits into a grin, uneven denta catching the low panel-light. "You don't want to leave, don't you?" He took immense delight in the unfairness of the situation, and reaffirmed their fears through praise, "Good little Mecha."

He stays crouched at eye level with them a while longer, not saying anything, simply being near—an enormity of cracked plating and red crest and needles at rest, blocking the exit with his shadow, filling the room. In the ring outside, water drips. Sunder's optics stay on them, and only on them.

He had been waiting for this longer than he'd let himself admit. The hunt had run long—longer than the others, longer than any of the quiet ones he'd pulled apart in the dark—and the drawn-out length of it had settled into him like heat into a spent blade. His chassis had been running hot for days. The plating over his core had scraped and clicked every time he moved, and every time he pressed his servos to something that wasn't them he felt a low, animal impatience coil up through his midsection. Obsession was rare for him. Obsession this specific, this persistent, had become something else entirely.

So when he finally bore them down onto the station floor, the sound he made was not a laugh exactly. It was too wet for that.

His mass came down over them and the old tile cracked under the combined weight of them, dust jumping off the derelict machinery around the platform. One servo clamped the back of their helm and pressed, unhurried and absolute, until their faceplate was grinding against the buckled plating underfoot and the joints of their neck had nowhere to go. His other hand went to the plating between their thighs—found the modesty panel and did not ask, did not fiddle, simply hooked its edge and wrenched it free in one clean tearing motion, throwing the piece aside so it clattered down into the rail trench. His ventilations had gone ragged and fast. Strands of hot vapor spilled out of his shoulder seams. He was grinning so wide that the unevenness of his denta showed all the way up his gaunt cheeks, and the disc in his forehead pulsed red in time with his spark.

"There you are," he breathed, nearly reverent, leaned low over their spinal struts with his helm almost touching the back of theirs, "There you are. Do you have any idea how long I have—no. No, you don't. You don't get to know that yet." His digits dragged over the exposed, unbonded seam, testing the warmth of it, the flinch of it, the way the frame under his palm couldn't decide whether to lock up or shiver. He pressed two fingers flat and dragged them slowly, deliberately, along the sensitive plate-edge just beside it, just to feel the reaction travel up their back struts into the hand still pinning their helm. His hips had ground down against the small of their back without his quite deciding to do it, the ache of his own closed modesty plating making his whole lower frame throb. He'd been strutting around like this for cycles. Now he was on top of the thing he'd built the ache for.

The needles began to extend out of the servo on the back of their helm.

They slid out of his fingertips one by one against the slope of their neck, cold-tipped and gleaming, each extended inch drawing a slow answer out of the frame beneath them. He let them feel it. That was the point. He wanted the anticipation to land before the incision did—wanted the exact nanoklik where they understood what was coming to be a thing he got to watch at point-blank range. His voice dropped into something almost gentle, crooning, while his left servo kept their helm flat to the floor and his right hand kept moving lower, lower, exploring the stripped-open plating with a curiosity that had nothing kind in it.

"I've been so good to you," *he murmured against the back of their helm. "Left you trails. Left you presents. I even let you think you were the one doing the hunting." His needles touched down at the base of their neck, right where the spinal struts met the rear of the helm—the seam he could find on a dead mech in total darkness—and hovered there, poised, one slow breath away from sinking in, "Now hold still. I want to see what's underneath you. I've earned this..."

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