They reached the first real maintenance platform and the refinery stopped being a looming thing above them and became a place that could hurt you.
The hum that had been haunting the town's streets tightened into something physical up here—pressure under the skin, the kind that made your jaw want to clench without permission. The pipes were louder at close range. Not louder like volume. Louder like intent. Everything up here had a purpose, and none of those purposes cared if you were human.
A trooper shoved a door open and the air changed instantly—hotter, drier, threaded with a sharp metallic tang that sat on Zack's tongue like he'd licked a battery.
Transparent conduits ran along the platform walls in thick bundles, like somebody had decided veins should be architectural. Mako poured through them in violent surges—too bright, too fast. Not the steady glow you saw in training vids. This stuff looked agitated. It didn't flow so much as slam forward, pulse hard, recoil, and slam again, luminous and pissed off, like the planet was fighting the machine from the inside.
Zack stopped without meaning to.
For a second his brain did that soldier thing—catalogue, assess, normalize—until it couldn't. The mako light was so intense it painted the inside of his eyelids green. He could swear he saw shapes inside it, not faces exactly, not bodies, but the suggestion of motion that wasn't turbulence. The suggestion of want.
He let out a laugh that didn't have humor in it.
"This feels… wrong."
His voice came out quieter than he meant, like he didn't want the refinery to hear him.
Sephiroth didn't stop.
He walked right up to the conduits and looked at the mako like it was a truth serum. Like it was finally telling him something straight without Shinra's polite packaging. The green light caught the edge of his cheekbones and made him look carved again—cold, pristine, unbothered.
"It feels honest," he said.
Flat. Not comfort. Not reassurance. A verdict.
Zack stared at him for a beat too long.
Honest. Sure. Honest like an open wound. Honest like seeing the inside of something you weren't supposed to see and realizing it's been there the whole time, just hidden behind paint and propaganda.
One of the troopers shifted his weight, boots scraping metal. Even that tiny sound felt swallowed by the refinery's grind. The Captain cleared his throat as if he could cough the tension out of the air.
"We'll proceed to the reactor inspection route," he said quickly. "Research wing access is restricted, but—"
"But," Zack echoed, because he heard the but the way you hear a trap snap.
The Captain's eyes flicked to Sephiroth and away again. He was sweating at the hairline.
Sephiroth didn't acknowledge him. He kept staring at the mako rushing through glass like a river being forced to confess.
Zack tried to talk himself down. Mako exposure did weird things. Everyone knew it. SOLDIERs pretended it didn't, but they all knew. Headaches. Static in the skull. Dreams that didn't feel like yours. You learned to file it under occupational hazard and keep walking.
Except this didn't feel like a headache.
This felt like the building was a mouth and the Lifestream was trapped between its teeth.
Zack dragged his gaze away before he started seeing things he couldn't unsee and followed as the Captain led them off the platform, deeper into the refinery's ribcage.
The corridors narrowed into something more controlled. Less industrial, more institutional. The floor plates changed from scuffed metal to cleaner panels. The lighting went from harsh work-lamps to cold strips that didn't cast shadows so much as erase them. The air got filtered. Sterile. Like Shinra believed cleanliness could be a moral stance.
They reached a checkpoint door set into the wall—heavy, sealed, with a keypad and a small camera eye that stared back without blinking.
RESEARCH WING — AUTHORIZED PERSONNEL ONLY was stamped across it in Shinra block lettering, because of course it was. Shinra loved a sign that pretended rules were the same thing as ethics.
The Captain stepped forward, shoulders tense.
"Sir," he began, and Zack could hear the plea in it. Please don't make me do this. Please don't make me admit this place exists. Please don't make me be responsible for what happens if you go in there.
Sephiroth moved past him like the man was furniture.
No hesitation. No glance at the warning. No "what is this" curiosity.
He raised a hand to the keypad and entered a sequence without looking down, fingers steady, certain. Like he'd done it before. Like his body remembered. Like the door was supposed to open for him.
A soft chime sounded.
The lock clicked.
The camera eye blinked once—an obedient little gesture—and the door slid open with a sigh, smooth and welcoming, like it had been waiting.
Zack felt something settle cold in his gut.
He looked at the Captain.
The Captain looked anywhere else.
Inside, the research wing didn't feel like part of the refinery at all. It felt like a different world wearing the refinery's skin.
The hall was brighter, quieter in a way that made Zack's ears ring. The walls were pale, too clean, too featureless. The smell hit him first: antiseptic layered over old paper and plastic and something faintly sweet that didn't belong in a place like this. The kind of sweetness you associated with preserved specimens and sealed jars.
This was where Shinra kept the things they didn't want the public to have words for.
Rows of cabinets lined the corridor, some locked, some sealed with red warning tabs. Monitors sat dark behind glass. A few were active—graphs scrolling silently, numbers marching across screens like they were counting down to something.
They passed a window into a side room and Zack's eyes snagged on it involuntarily.
Tanks.
Not huge ones—not yet—but enough to make his shoulders go rigid. Cylinders of cloudy liquid. Labels. Barcodes. A rack of specimen trays covered with white cloth like bodies in a morgue.
He told himself it was probably animal samples. Reactor contamination testing. Environmental impact reports. Anything boring.
Then he saw a shape floating in one of the tanks—too big for a rat, too wrong for a fish—and he had to look away or his face would do something he couldn't control.
Sephiroth didn't look away.
He walked through the research wing like it belonged to him. Not in a smug way. In a way that made Zack's skin crawl, because it wasn't confidence. It was familiarity.
He didn't read the signs. He didn't slow down at junctions. He didn't hesitate at the second sealed door—just keyed it open, same calm, same certainty. Like the building recognized him and the building wanted him inside.
Zack tried to speak, tried to keep the thread of normal conversation alive the way he always did when something started going off the rails.
"So," he said, voice deliberately casual, "this wasn't on the tour last time I came here."
Sephiroth didn't even turn his head.
"This is where the truth is kept," he said, like it was obvious. Like it was pathetic Zack had to ask.
They entered the archive proper and the space opened into something that felt almost sacred in its own ugly way—rows and rows of file cabinets, terminal stations, locked drawers, shelves stacked with binders whose spines were stamped with dates and project codes. A library, sure.
A library built out of secrets.
Zack stepped in and the air felt different, heavier, like a pressure change before a storm. The hum from the refinery was still there, still threaded through everything, but muffled now by walls meant to contain it. Like Shinra believed concrete could silence a planet.
On one side of the room, a set of glass-front storage units held more tanks, smaller and more numerous. Samples suspended in fluid. Tissue slices mounted like little moons. Vials arranged with obsessive precision. The whole setup had the polite, clinical vibe of "science" and the underlying energy of "we did this to something living."
Zack's hand flexed near his sword strap without his permission. A reminder. A comfort. A threat. He didn't know which.
Sephiroth moved deeper into the archive and for the first time since Nibelheim, Zack saw something that looked like purpose in him—sharp, directional, inevitable. The way a compass needle snaps toward north.
It wasn't curiosity anymore.
It was homecoming.
Zack watched him for a long moment, and the thought slid into his mind like a splinter:
Sephiroth wasn't being led by Shinra.
Shinra was just the hallway.
Whatever was calling him—whatever had whispered come home—was in here.