The gantry trembled under them like it regretted being built. A thin strip of metal stretched over the core, railings too narrow to feel like protection and too present to let you forget how far down "down" went. The mako below didn't glow so much as insist—a roaring river of green-white light churning through open channels like the planet's bloodstream had been dragged into the open and told to behave. Heat rose in thick, warping sheets, bending the straight lines of Shinra's geometry until even the rules of perspective looked tired.
Zack kept his feet planted anyway.
He could feel the vibration of the turbines through the soles of his boots. It traveled up his bones like a second pulse, foreign and intimate, like the refinery had decided it deserved to live inside him too. The Buster Sword hung heavy in his hands—heavy with metal, heavy with every stupid promise you ever made and didn't realize you'd have to pay for.
Across from him, Sephiroth looked… settled. Not calm the way a person got calm when they made peace, but calm the way a blade got calm when it found its angle. The dried streak of blood on his cheek looked less like damage and more like decoration, a small mark the world had tried to give him and failed to make meaningful.
Zack swallowed. His throat tasted like smoke and copper and that sick-sweet mako bite that always made him think of lightning and hospitals in the same breath.
"Stop," Zack said, and he hated how human it sounded in this place. The refinery didn't speak in human. The mako didn't care about human. "Don't do this."
Sephiroth's gaze didn't harden. That was still the worst part. If Sephiroth had yelled, Zack could've yelled back. If Sephiroth had looked angry, Zack could've called it a phase, a fracture, a moment that could be pushed through.
But Sephiroth looked at him with something almost patient, like Zack was standing in the doorway of a room Sephiroth had already left.
"You're walking into something you can't come back from," Zack said, forcing the words out steady. Not a lecture. Not a soldier's warning. Just the truth said plainly, like maybe plain truth could still get traction on a floor this slick.
The hum under the gantry tightened, just slightly, as if the building was leaning in to hear the answer too.
Sephiroth shifted his grip on the Masamune with ritual care. The blade caught the mako light and turned it into a thin, cold line—beautiful in that clinical way that made you think of operating rooms and funerals.
"I'm finally going where I was made to go," Sephiroth said.
The sentence landed like a nail tapped into place.
Zack felt something inside him twist—because there it was, the shape of the lie that was almost indistinguishable from a revelation. Made. Assembled. Designed. The words from the archive, the paperwork that wanted to be scripture. Shinra's favorite trick: tell you what you are, and then act surprised when you start behaving like it.
Zack took half a step forward without meaning to, like his body still thought it could close distance and solve this with hands and stubbornness.
"Made by who?" Zack shot back, sharper than he intended. The heat made everything short-tempered. "Shinra? Hojo? A file? A voice in the pipes? You really wanna let that be your compass?"
Sephiroth's eyes flicked past Zack for an instant—past him, through him—toward the access gate below the gantry, toward the heart of the refinery like it was a mouth waiting to be fed.
Zack's stomach dropped with the realization that Sephiroth wasn't just trying to get past him.
Sephiroth was trying to end him.
Not out of anger.
Out of necessity.
Like removing the last obstacle between himself and something he'd started calling "real."
Zack tightened his grip until the leather creaked.
"Seph," he said again, quieter now, like lowering your voice could turn the whole world down with it. "I'm right here. I'm not your chain. I'm—"
Sephiroth moved.
It wasn't a step. It wasn't a warning. It was an answer delivered in steel.
The Masamune lunged forward with impossible elegance, fast enough that Zack's eyes registered motion before his brain registered intent. The blade cut the air so clean it felt like it split the heat shimmer itself. For a heartbeat, it looked like the world was being sliced into two versions—one where Zack stopped him, and one where Zack didn't exist anymore.
Zack's body reacted before his mind caught up.
The Buster Sword snapped up, broad face meeting the Masamune's line with a violent metallic ring that shot through Zack's arms like a tuning fork struck against bone. The impact drove him back a half-step—boots skidding on wet grating—and the sound didn't just echo.
It vibrated.
It rang through the gantry, through the railings, through the scaffolding, into the mako roar below, and for a split second the refinery's hum seemed to harmonize with it, like the whole building approved of the attempt.
Zack's elbows jarred. His wrists went numb and then burning. The Buster Sword felt like it weighed twice what it had a second ago, like the refinery had reached up and grabbed it too, trying to pull it out of his hands.
Sephiroth didn't stop.
He pressed in with merciless precision, blade angling for a decisive end—throat, heart, spine, anywhere that turned a person into a "before" and "after." His movements weren't wild. They were perfect. Each strike placed where Zack would have to answer it with all his strength, all his focus, all his remaining seconds.
Zack staggered, blocking on instinct, the Buster Sword catching the Masamune again and again, each collision punching a new note into his arms. His shoulders screamed. His lungs felt too small for the air. Sweat ran down his spine cold despite the heat, like his body couldn't decide whether it was in a furnace or a morgue.
"Sephiroth!" Zack barked between impacts, voice tearing. "Listen to me—"
Steel hit steel. Sparks snapped bright and brief, orange flecks swallowed by green light before they could even fall.
Zack's boots slid another inch toward the edge.
His heel kissed the seam where the gantry narrowed.
His stomach lurched as the mako glow flared beneath him, bright enough to make the underside of his eyelashes glow green. The heat rose in a gust, and for a second it felt like the core was breathing up at him—like the planet's blood was reaching for his sweat, his fear, his grief, taking inventory.
Zack shoved back with everything he had, muscles trembling, forcing the Buster Sword to hold the line.
Sephiroth's eyes stayed clear. Calm. Certain.
And Zack realized, with a cold jolt, what Sephiroth was trying to do.
Not just kill him.
Make it quick. Make it clean. Make it the kind of ending that didn't leave room for regret to crawl back in later.
Zack's jaw clenched so hard it hurt. He leaned into the next block, teeth bared, voice low and furious through the roar.
"You want to talk about what you were made for?" he rasped. "Fine. Then look at me and tell me you were made for this."
Sephiroth's Masamune pressed against the Buster Sword's face, metal bowing under force, the contact point screaming with strain. Sephiroth leaned in just enough that Zack could see the dried blood on his cheek up close—dark, thin, unimportant—and the mako light turned Sephiroth's eyes into something not quite human.
"I'm done being small," Sephiroth said softly, almost like an apology.
Then he drove forward again, trying to break Zack's guard in one decisive surge.
Zack barely held it.
The impact rang through his arms so hard he saw stars for a blink—tiny, stupid stars in a place that had nothing to do with the sky.
He didn't fall.
Not yet.
But the gantry shuddered beneath them like it could feel the weight of the moment settling in, and Zack understood, with awful clarity, that whatever happened next wouldn't be reversible.
Some doors didn't open back.
And Sephiroth had already stepped through.