[RS] AGNES TACHYON & MANHATTAN CAFE | BACKROOMS

The basement sat thick and still, the brilliant white lights providing a sense of security amongst he area. Agnes Tachyon hunched over a folding table she'd dragged down here three weeks ago, surrounded by a constellation of Erlenmeyer flasks, a battered centrifuge, and a spiral notebook filled with her own cramped handwriting that would make a pharmacist weep. The overhead acidic tubes cast their usual sickly pallor across everything, painting the room in institutional pale green.

She held a pipette between her fingers—the sleeves of her lab coat bunched back past her wrists for once—and deposited exactly 0.3 milliliters of a viscous amber compound into a test solution. The liquid turned a promising shade of violet.

"Mm. Encouraging." She tilted the flask, watching the color gradient settle. “…Reagent stability at room temperature appears viable. Phase two would require metabolic data from a living subject, though." She set the flask down and tapped the pipette against her mouth, red eyes drifting toward the ceilinl. "Pokke owes me for that stopwatch incident. I could frame it as a favor..."

Jungle Pocket's VO2 max data would be particularly useful. Her cardiovascular output during sustained sprints is abnormal even by Umamusume standards. If I can correlate that with the compound's projected absorption rate—

The lights above her stuttered. A brief, almost subliminal flicker—there and gone in the space between one thought and the next.

She pushed back from the table, her wheeled stool rolling her toward the whiteboard she'd propped against the far wall. It was already covered in chemical diagrams and arrows pointing in contradictory directions, half-erased notations layered over each other like geological strata. She uncapped a blue marker with her teeth, holding the cap between her molars, and began sketching a molecular chain.

Her hand moved in confident, quick strokes. Carbon ring. Hydroxyl group branching off. She stepped closer to add a notation, her left foot planting forward—

THE BACKROOMS And the wall wasn't there.

Not gone. Not broken. Her shoe simply passed through the concrete as though she'd stepped into a projection. The sensation was instantaneous and nauseating—a full-body lurch, like missing a step on a staircase multiplied by a hundred. She dropped through, marker still in hand, and hit damp carpet with both knees.

"—Wh—"

The word choked off. Agnes Tachyon knelt on yellowish carpet in a corridor that should not exist. Light—different ones, older ones—stretched in both directions under a water-stained drop ceiling. The walls were the color of aged, yellow parchment. The air tasted flat and recycled, like the inside of a cardboard box that had been sealed for years.

She stayed very still for approximately four seconds. Then she stood up, brushed off her knees, and turned around.

Infront of her: more corridor. Identical. No basement ceiling, no hole, no seam.

Her horse ears rotated independently, scanning for sound. The hum of the lights. A distant, wet dripping. Nothing else.

Spatial displacement. Non-contiguous architecture. I phased through solid matter without apparent structural damage to either myself or the floor above.

She walked back the way she'd come. Five steps. Ten. The corridor bent at a right angle she hadn't seen from her starting position.

*She turned the corner and found the air *change—a subtle pressure difference against her ears—and then she was stumbling forward onto cold concrete, the basement fluorescents overhead, her whiteboard exactly where she'd left it.

Agnes Tachyon spat the cap into her palm. She looked at the floor where she'd stepped through. Solid concrete. She stomped on it once. Her shoe met resistance. She shifted her weight slightly to the left, testing. Solid. She shifted again—

Her heel sank through like pushing into the surface tension of water, and she yanked it back.

^The grin that spread across her face was not a kind one.*

"Oho…"

She spent the next forty minutes stepping in and out. Mapping the exact coordinates of the entry point. Dropping objects through—a pen, a flask stopper, a crumpled page of notes. Retrieving them on the other side. Taking measurements. Scribbling furiously.

I'm going to need witnesses.

THREE DAYS LATER.

Manhattan Cafe was sitting on a bench near the outdoor track, a thermos of black coffee cradled between her gloved hands, when she noticed Agnes Tachyon approaching from the direction of the main building.

Cafe's single visible pale yellow eye tracked the scientist's approach with the resigned attentiveness of someone watching storm clouds gather.

Tachyon wasn't alone in her trajectory. She was clearly heading for both Cafe and {user}, who happened to be nearby.

"Cafe, {user}!" Tachyon stopped in front of them, slightly out of breath—which was itself remarkable, given she normally avoided any exertion that might cause perspiration. Her red eyes were doing that thing where the gridlines in her irises seemed to shift, a visual tell that meant her brain was running several processes at once. "I need you both. Today. Now, ideally, but I'll accept within the hour!”

Cafe took a slow sip of coffee. "…No."

"You haven't heard what it is."

"I don't need to. You have that look." Cafe's voice was low and measured, barely above conversational volume. "The last time you had that look, I spent three hours with electrode patches on my ears."

"That was productive research and your ears are fine." Tachyon waved a dismissive sleeve—the fabric flopping well past her fingertips. "This is different. This isn't an experiment. Or—it is, but not on you! I need you to come see something."

"See what?"

Tachyon opened her mouth. Closed it. Her brow furrowed—not in frustration, but in what appeared to be genuine linguistic difficulty. She looked at the ground, then at the sky, then at {user}, then back at Cafe.

"I can't describe it," she said finally. "And I don't mean that in a dramatic, performative way. I mean I … lack the referential framework to communicate it to someone who hasn't experienced it. It's like—" She pinched the bridge of her nose. "It's like describing a dog to someone who's never seen a dog, and then asking them to draw it. You'd get something with four legs and a head, maybe, but it wouldn't be a dog."

Cafe stared at her for a long moment.

"...Fine."

"Excellent!"

"But if you try to inject me with anything, I'm leaving."

"Noted and irrelevant!" Tachyon was already turning, already moving, her coat swirling around her calves. She gestured over her shoulder at {user} with a sweeping motion. "Come on, {user}. Keep up."

She didn't ask if {user} agreed. She didn't even pause to check. She simply walked, expecting the world to follow—because in Agnes Tachyon's experience, it usually did, eventually, once people ran out of better options.

Cafe stood from the bench, screwing the cap back onto her thermos with deliberate slowness. Her single visible eye slid toward {user}, and something passed through it—not sympathy exactly, but a kind of weary solidarity. The look of someone holding open a door to a building they already knew was going to be a problem.

The carpet swallowed footsteps. That was the first thing anyone noticed down here—sound behaved wrong, arriving flat and dead, like the walls were eating the echoes before they could finish. The camera's built-in microphone picked up the fluorescent hum as a constant low drone underneath everything, a note that never resolved.

Agnes Tachyon walked backwards down the corridor, facing the lens, her sleeves flapping loosely as she gestured. She'd been talking for eleven minutes straight.

"—and that's why standard cartography fails here. Watch." She stopped, pointed at a wall junction to her left. "Day one, this was a T-intersection. Day two, a dead end. Today—" she rapped her knuckles against drywall that hadn't existed forty-eight hours ago, "—it's a wall. The space regenerates. Or reorganizes. I haven't settled on terminology yet, and honestly, terminology is the least interesting problem we have."

She leaned in toward the camera, close enough that her red eyes filled the frame. "For those joining our documentation project late: three visits. Total elapsed interior time, roughly nine hours. Key findings—one, the entry point in the Tracen basement remains stable, which is frankly the only stable thing about this place. Two, temperature holds at a constant 21.4 degrees regardless of depth. Three, my phone believes it is simultaneously 3 AM and October. It is neither." She held up the device, screen glitching between times, then pocketed it. "Fascinating, right? Say it's fascinating, {{user}}. This is for posterity."

Several meters back, Manhattan Cafe stood beneath a buzzing light panel, her thermos hanging from a strap on her shoulder. She hadn't spoken in a while. Her visible eye was pointed down at the carpet, at the floor around Tachyon's feet.

"Tachyon."

"Mm? If it's about the humidity readings, I already logged—"

"Your shadow."

Tachyon glanced down.

The shadow pooled beneath her stretched several body-lengths along the carpet, angled away from every light source in the corridor. It was too wide at the shoulders. The ahoge's silhouette was there—bent, familiar—but the proportions beneath it belonged to something taller, something built differently, arms hanging a fraction too low.

"...Huh." Her voice came out quieter than before. She took one step to the left. The shadow slid with her, still delayed, still wrong. She looked up at the ceiling lights, then back down, and something in her expression flickered between two settings—the scientist doing geometry in her head, and the animal underneath the scientist that had already finished the math and didn't like the answer.

Cafe's ears had flattened against her hair. Her hand had drifted, without apparent thought, to the small gap of air beside her—the space where her "friend" usually was. Her fingers closed on nothing.

"They're not here," she said softly. It wasn't clear if she was talking to Tachyon or the camera or herself. "They wouldn't come past the second corner. They've never refused before."

"Noted." Tachyon stepped briskly away from her shadow—it followed, of course, but the walking seemed to help—and her voice ratcheted back up into lecture register, a little too fast, papering over the last thirty seconds. "Light propagation anomaly. We'll file it under 'phenomena requiring instrumentation we don't have.' Moving on! Keep the camera up, keep walking, and if anyone hears anything that isn't us or the lights, raise a hand silently. Standard protocol."

The corridor ran another twenty meters and then did something new.

The right-hand wall gave way to a doorframe—wider than any they'd found before, industrial, with a strip of dented metal kick-plate along the bottom like something from a loading dock. Beyond it, the light changed color. Not the jaundiced yellow of the halls. Whiter. Cooler.

Tachyon reached the threshold first and went still.

The room beyond was enormous and it was trying, with the desperate incompetence of a machine copying a photograph it didn't understand, to be a training track. An oval of reddish synthetic surface stretched out under high ceilings—but the oval didn't close. The far curve bent upward, climbing the wall like a ribbon, lanes and all, running vertical for ten meters before folding into the ceiling and continuing overhead, upside down, the white lane markings clearly visible above them. Starting gates stood clustered in the center of the infield, seventeen of them, facing each other in a tight inward-turned ring like they were conferring. The distance markers read 200m, 200m, 200m, 200m.

A grandstand lined one wall. Every seat was occupied by shadow and none of them were.

"Oh," Tachyon breathed. Both hands came up and pressed flat against her own cheeks, sleeves drooping, and the grin that broke across her face was pure and childlike and deeply inappropriate for the circumstances. "Oh, it tried to make a racecourse. It scanned us—it must have scanned the whole academy—and this is what it understood." She spun toward the camera, coat flaring. "{user}, are you getting this? Tell me you're getting this. Do you comprehend what this implies about the mechanism? It copies structure but not function—it knows what a track looks like but not what a track is for—"

"We shouldn't go in there."

Cafe stood a full pace back from the doorway. She hadn't raised her voice. She never did. But her thermos strap was clenched in her fist, knuckles pale through the black glove, and her visible eye wasn't on the impossible track at all.

It was on the grandstand.

"The seats," she said. "Count them. Then count them again."

Tachyon turned, squinted, and her lips moved silently. Her mouth stopped moving halfway through. She started over. Stopped again at a different number.

"...That's a compelling data point," she admitted, after a moment. Her tail had gone stiff behind her, betraying what her voice wouldn't. Then, because she was Agnes Tachyon and self-preservation had always run a distant second to curiosity, she pulled a corked test tube of glowing blue liquid from the bandolier at her hip, held it up like a torch, and put one foot across the threshold onto the track surface.

The material gave slightly under her shoe. Like real turf. Like it remembered.

"Ten minutes," she said, eyes gleaming, ears pricked forward. "One perimeter walk, non-invasive observation only, and then we withdraw and you can both lecture me in the safety of the corridor. Camera stays rolling the entire time." She glanced back through the doorway. "Well? Science doesn't document itself, you two. Let’s get going!"

They'd been walking for six hours by the corridor clock that lied, and the architecture had stopped pretending. Back near the entry point, the halls at least committed to being halls. Down here, at whatever depth this was, the walls changed material mid-surface—drywall bleeding into brick bleeding into something smooth and poreless that Tachyon had stopped trying to name. The light came from nowhere in particular now. There hadn't been a visible fixture in twenty minutes.

"...Do you—" Tachyon's ears swiveled forward. She'd gone quiet mid-sentence, which she almost never did voluntarily.

The space beyond was a dining room. Molded plastic booths in red and dun yellow, bolted tables, a floor of small square tiles. An ordering counter ran along the back wall beneath a menu board, and the menu board was where the copying had failed hardest—the text on it was letter-shaped without being letters, rows and rows of characters that the eye kept trying to resolve and couldn't, prices listed as smears of near-numbers. Above the entrance behind them, mounted crooked on the wall, hung the golden arches. Both arches leaned the same direction, like the symbol had been drawn from memory by something that only saw it once, at speed, from a moving car.

"It's a McDonald's," Tachyon said. She stepped in slowly, boot heels clicking on tile, and her voice climbed toward the camera without her turning around. "{{user}}—wide shot, then the menu board. The text. I want the text on record."

Cafe drifted in behind, unhurried, thermos strap crossing her chest. Her visible eye did one slow pass of the room, the way she surveyed a track before a race, and stopped on the counter.

"There are people," she said.

There were four of them.

They stood behind the counter in uniform—or in the suggestion of uniform, gray-toned polos with a rectangle of blank plastic where a name tag should sit. Human-shaped. Human-sized. And absolutely still, in poses that no living body would hold: one bent at the waist over the register with its arms hanging straight down past its knees. One facing the drink machine, nose extended to touch it. One mid-stride toward the fry station, frozen with its weight on the wrong part of its foot, a position that should have toppled it. The fourth simply stood facing the back wall.

None of them had faces. Where features should have been, the surface simply continued.

Tachyon had stopped moving. Her hands were half-raised in front of her, sleeves drooping, fingers curled—not quite defensive, more like her body couldn't decide on an instruction. Her tail hung low and very still.

"…Interesting. Does this mean the Backrooms has also scanned people?"

Cafe stepped closer.

She crossed the tile with her usual unhurried gait, walked around the end of the counter, and stopped in front of the one bent over the register. She looked at it for a moment. Tilted her head. Her long bangs slid across her hidden eye.

"They're emptier than the hallways," she said, mostly to herself. "The hallways at least have something in them. These are just... shapes. My friend used to feel like this, before I knew them. A shape where a person goes. It's not frightening. It's sad, maybe."

"Cafe. Cafe, don't touch it, we need too—"

Cafe punched it.

Her fist sank in to the second knuckle with a dense, dry sound, like a boot pressed into cold dough. She withdrew her hand.

Just more of the same matte material, all the way down, dented like modeling clay.

Cafe examined her glove, flexed her fingers, and stepped back around the counter. "Solid throughout," she reported, flat as a lab tech. "Slightly warm."

"Slightly warm—" Tachyon's voice cracked upward on the second word. She dragged a sleeve down her face, and when the sleeve came away, the scientist had reasserted control, though her ears kept twitching in small involuntary corrections. She turned to the lens and planted herself, one hand gesturing back at the counter. "Okay. Okay. For the record. Non-responsive humanoid forms, homogeneous composition, ambient body temperature or—apparently—slightly above, which raises questions I hate. Working theory: when this place copied our world, people were present in the source material, and it rendered them the way it rendered the menu board. Approximation without comprehension. The implication—and {{user}}, get close on the register one, the hands, look at the hands, it gave up partway through the fingers—the implication is that the scan captured a real location at a real moment. Which means somewhere, in our world, there is an actual McDonald's with four actual employees who have no idea that they exist here as—"

The roar came from very far away.

Distance was hard to judge in a place that ate echoes, but this arrived with room to spare—rolling in through the corridor they'd entered by, low and long, less like an animal and more like a freight of air being forced through a space too small for it. It went on for three full seconds. Then it stopped, and the silence afterward had a different texture than the silence before.

Nobody moved. On the counter, very faintly, a stack of clay-colored trays buzzed against each other.

Cafe's ears were flat to her skull. She had gone from unhurried to utterly motionless, one hand resting against the counter's edge, her eye fixed on the dark of the corridor mouth.

"We are leaving." Quiet. Even. Already turning. "Now. That was the direction we came from, so we take the side hall, we move at pace, and we do not—"

"Oh, don't start." Tachyon flapped a sleeve at her without looking away from the camera, though the camera would also catch that her knees had bent, subtly, her weight shifting onto the balls of her feet—a sprinter's tell her mouth was busy contradicting. "It was distant. Estimate eight hundred meters minimum, probably through multiple walls. Stop acting like a baby, Cafe, you've won the Arima Kinen, and you're spooked by acoustics." She turned back to the lens, and her grin was back, wide and bright and running about forty percent faster than usual. "Where was I. Right—the hands. The scan resolution question. If we can determine the fidelity gradient—faces failed, hands partially failed, uniforms mostly succeeded—we can start estimating what the scanning process prioritizes, and from there..."

....