The Null Body collapsed from the chest outward.
Its broken core released one last pulse before crumbling into pale powder. Thin white fluid followed, running across the shattered ribs and dripping between the floor plates. The powder should have settled beside the wreckage, but the first strand lifted toward Kael's bloody hands.
HISS!
More strands rose from the corpse. They reached for footprints, torn bandages, and the dents left by Kael's attacks. A survivor beside Renn gasped when the powder touched his sleeve and began smoking over an old bruise.
Renn caught the man's wrist before he could run. His damaged throat reduced the warning to a rasp, but his fingers found the pulse. "You are still breathing. Keep your mouth covered and stay with me."
Orrek stepped between them and the falling powder. One arm remained close to his ruined shoulder, while the other held the shortened chain away from the survivors. "Use my coat for cover. The room has already taken enough interest in this shoulder."
A white line crept across his torn sleeve.
"Move back," Kael said. "It is following the wound."
Orrek obeyed before the line reached his skin. Renn guided the shaken man behind a broken pillar, and the other twenty people tightened their hand-to-hand count without crowding him.
The chamber had changed since the fight. Pale grains coated every place where a body had bled or struck stone, while the untouched floor remained dark. Powder gathered inside Kael's heel prints and traced the path of Vaela's blade along the wall.
Vaela crouched near a blackened patch and held the damaged white edge above it. Her numbed thumb forced her to support the grip with two fingers. The powder climbed toward the metal, stopped beneath the chipped point, and arranged itself along the exact angle of her last cut.
"It remembers contact," she said. "Keep your hands and tools clear. We still do not know what makes it move."
Jaro studied the powder from behind her. "The old crews called the residue protocol ash. Failed countermeasure bodies left it behind when the rooms wanted to keep learning."
Vaela glanced at the moving line rather than at him. "What can it do before it reaches skin?"
"It follows blood, scars, and repeated work. Once it has enough of a pattern, the next room can prepare for whoever made it."
Powder ignored clean stone, thickened around Orrek's blood, and copied the angle beneath Vaela's edge.
Renn kept his hand around the smoked survivor's wrist. "How did your crew learn to avoid it?"
Jaro rubbed his bandaged palms against his coat. "We scrubbed every footprint after one of these bodies failed. The next chamber still broke three men at the knees because they lifted the same carts. I survived because fear made me drop mine before the door opened."
The survivor looked at the white line on his sleeve. "Will it remember me now?"
Vaela drew him closer and cut the smoking cloth away without touching the powder. The bruise beneath it remained dark but unburned. "It has seen one injury and one frightened movement. Give it nothing else clean enough to use. Keep this arm against your chest and change which foot leads when Renn moves you."
The man forced himself to breathe before nodding again. Renn stayed until the pulse slowed.
Kael opened his injured right hand. A narrow strand curved toward the split skin, but it stopped before touching him and trembled in place. His density settled lower through his stance as he watched it search for a safe approach.
He had no shards to spend. His body, his people, and the lessons already paid for were all he carried into the next decision.
Powder scraped through three cracks in the ceiling above the clustered survivors.
RUSTLE!
It descended around them, avoided empty stone, and gathered wherever two bodies stood close together.
"Cloth over your mouths," Renn said. "Keep one hand on the person beside you, and leave enough room to move."
The woman at the rear could not free her cloth from dried blood. Tavin held her wrist steady while Dorran tore the strip loose with both hands. Sella moved her daughter between two adults before helping the next injured worker.
Renn touched every wrist in reach. "All twenty-one are here. Ash is gathering around us. Get moving."
Kael entered the passage first. His opening step landed heavy, the second fell short, and the third stopped before his weight crossed the heel. Behind him, the formation copied his direction while each pair kept a different rhythm.
HUM!
Ash gathered inside the first three footprints. A pale line joined them, crossed the floor ahead of Kael, and drew the place where his fourth step should land.
He placed his foot beside it.
CLINK!
The predicted mark broke like a thin glass tooth. Jaro flinched at the sound and pointed toward the next patch forming near Orrek.
"Do not let any line connect three movements," he said. "Change something before the third one finishes."
Renn passed the warning back in broken whispers. One pair changed which shoulder touched. Another shortened a step. Orrek let the chain drag for half a pace and lifted it before the ash could finish tracing the metal.
The powder on the floor abandoned their feet and gathered around Kael's last strike mark. A pale shape rose from it, showing his shoulder dropping, his hips turning, and his fist crossing the space where the Null Body had stood.
Kael stopped the formation with one raised hand. The ghostly strike moved without him and hit the wall.
THUD!
Stone dented beneath the copied fist. The blow lacked Kael's present weight, but it proved the residue could repeat what it had collected.
The Sovereign Root opened behind his eyes.
====================================================================
[ SOVEREIGN ROOT INTERFACE OVERLAY ]
--------------------------------------------------------------------
≫ WHITE-ROOM RESIDUE DETECTED: Impact Pattern Ash
≫ HOSTILE PRESSURE STATUS: Observational, non-extractive
≫ EXISTENTIAL SHARDS EXTRACTED: +0
--------------------------------------------------------------------
▶ MANUAL ALLOCATION COMMAND: NONE GIVEN
≫ SYSTEM NOTICE: Pattern capture attempt remains incomplete.
====================================================================
Observation gave him nothing. The copied strike had hit stone rather than his body, and the ash had not applied enough hostile pressure for the Root to convert.
"Do not follow my exact steps," Kael said. "Watch the marks and change before a line closes."
The twenty-one moved again. Renn guided the injured by touch, Vaela watched the ceiling cracks, and Orrek kept his body between the falling powder and the weakest pair. Jaro called each forming line only after he saw its path.
An older woman dragged her left foot twice. Ash joined both heel marks and drew a third ahead of her. Renn caught her waist and shifted her toward Tavin before it closed.
"My knee will not bend any other way," she whispered.
"Lean on Tavin for two steps and use me for the third," Renn said. "The ash cannot follow both injuries at once."
Tavin moved beneath her arm. His limp spoiled the shared pattern, and the ash failed to finish either mark.
Orrek saw a line forming beneath his chain. He wound the metal around his sound forearm, shifted its weight across his hip, and kept walking despite the pull on his shoulder.
SCRAPE!
A longer mark cut across the floor and curved toward the survivors. Kael planted his heel on its center before it could join his movement to Renn's count.
Cold pain pierced the sole of his boot. Ash curled around the heel and found a narrow gap beneath his weight, but the sting remained shallow. The Root stayed silent.
Vaela saw his calf tighten. "It reached the space under your heel. Drag across the line instead of lifting your foot, or it will keep the full print."
Kael ground sideways. The mark smeared into loose powder, and the pain broke into smaller points along his foot.
He wanted to crush the floor. The residue had recorded every direct answer he had used in the previous chamber, so he kept his fist closed and chose patience instead.
The ash withdrew from the passage ahead. A narrow strip of black stone appeared between the pale drifts, clean enough to look safe and straight enough to invite speed.
Jaro stared at it. "The residue has cleared one path for us. Old crews saw openings like this only when a room wanted them somewhere specific."
Vaela checked the dark strip with the blunt back of her edge. The stone did not move, but powder crowded both sides as if waiting to close behind them. "We have nowhere else to put twenty-one injured people. Use the black stone, but leave enough room to turn if the ash closes behind us."
Kael stepped onto the black stone. Ash pulled away from his boot and climbed into the ceiling cracks.
The formation followed in changing pairs. Renn counted by wrists, shoulders, and breath rather than spoken numbers. Orrek walked behind the injured man whose sleeve had smoked, keeping the chain ready without letting it touch the floor. Vaela watched the powder travel overhead.
Sella's daughter looked up at the moving ash. "Does it remember faces too?"
"It remembers what people repeat," Vaela said. "Keep holding your mother's hand, but change where you place your feet."
The girl moved from Sella's right side to her left without releasing her hand. Powder gathered over the empty place she had left.
"Like that?"
"Exactly like that," Vaela said. "Everyone else follows her example."
At the first bend, Renn checked the line again. Every pulse answered. Sella's daughter kept her cloth over her mouth and stared at the hand she held instead of the ash above her.
The residue still followed them, but their changing steps had denied it a complete record long enough to reach the path it wanted them to take.
Behind them, the last white ribs of the Null Body crumbled. Powder carried the failure through the ceiling while a deeper chamber began moving ahead.
Kael kept the twenty-one close and entered the bend as ash spread through the ceiling cracks above them.