Fate's Slave - Shadow Slave X Honkai Star Rail

The Robot Settlement had always been a lonely place.

Even at its busiest, when the displaced of the Underworld had camped among the rusting husks of ancient machines, it had carried the desolate atmosphere of a graveyard that people were merely borrowing for warmth. Snow had drifted unchecked across the open ground, piling against metal limbs and half-buried chassis, the wind whistling through hollow frames like something mourning what had once been alive. Clara’s mansion had stood at the center of that wasteland like an improbable sanctuary, equal parts shelter and relic, surrounded by a loose congregation of automatons who obeyed her with quiet devotion.

Sunny emerged from shadow expecting that same bleak familiarity.

Instead, he arrived into something that looked like the industrial fever dream of a civilization that had collectively decided subtlety was for cowards.

Snow still fell, but it no longer dominated the landscape. Vast swaths of it had been cleared into regimented berms, compacted into neat walls or melted entirely by heat vents embedded in the ground. Where empty tundra had once stretched to the horizon, structures now rose in tiered layers of steel, brass, and reinforced alloy, their silhouettes jagged against the pale sky like the teeth of some enormous mechanical beast pushing up through the earth.

Automatons moved everywhere.

Not wandering aimlessly as they once had, but marching, hauling, welding, assembling with synchronized efficiency that suggested centralized coordination on a scale that bordered on military. Some carried enormous girders balanced across multiple arms, others operated cranes that pivoted with smooth precision, while smaller worker units scuttled beneath them like metallic insects, securing bolts and reinforcing joints with bursts of blue-white sparks.

And dominating it all, rising like a monument to excessive ambition, was a weapon.

Sunny stared at it for several seconds, his mind struggling to reconcile what his eyes were reporting with any sane interpretation of reality. It resembled a cannon in the same way a mountain resembled a pebble, a colossal rail assembly mounted on a reinforced platform, its barrel angled toward the distant surface as though daring the heavens to start something. Steam vents along its length exhaled rhythmic plumes, pistons the size of train cars cycling slowly as internal pressure built and released with a deep, resonant thrum.

It looked less like artillery and more like a machine designed to bully planets.

"What. The. Fuck."

The words left him with heartfelt sincerity.

He took a few steps forward, boots crunching against compacted snow that had been flattened into something approaching pavement, head swiveling as he tried to process the sheer scale of construction. Towers rose in the distance, some clearly habitation modules, others bristling with antennae and sensor arrays that swept the sky in slow arcs. Conveyor lines ran between buildings, transporting components with mechanical efficiency, while energy conduits glowed faintly beneath translucent shielding, pulsing like veins beneath synthetic skin.

This was not a settlement.

This was an empire under construction.

Several nearby automatons noticed him simultaneously, optical sensors swiveling in unison before their postures shifted into something that might generously be described as welcoming. They halted their tasks, turned toward him, and spoke in perfectly synchronized monotone.

"Welcome back, Mister Sunny."

He blinked at them.

They blinked back, or at least their lenses dimmed and brightened in a manner that approximated it.

Sunny opened his mouth, closed it again, then slowly turned in a full circle as though expecting someone else to step forward and explain the situation. When nobody did, he pinched the bridge of his nose, muttering something deeply uncharitable about children left unsupervised.

Shadow gathered at his feet without ceremony, swallowing him before the automatons could resume their work.

He reappeared at the base of Clara’s mansion, which had apparently decided to participate in the local arms race.

The original structure was still recognizable, its stone walls and steep roofline intact, but additions had sprouted from it like aggressive architectural tumors. Reinforced annexes extended outward, their windows shielded by armored shutters, while new towers rose from the corners, each topped with rotating sensor dishes. Most alarming of all was the enormous telescope protruding from the roof, its barrel angled skyward, rotating with slow deliberation as though tracking objects far beyond the atmosphere.

Sunny tilted his head back, following its motion, and briefly considered the possibility that Clara had decided to personally monitor celestial bodies for signs of disrespect.

Then his shadow sense brushed against something beneath the building.

He froze.

It was not the presence itself that alarmed him, but the absence of limits. His perception flowed downward through stone, steel, and reinforced alloy, expecting to encounter bedrock or the natural boundary of his range. Instead, it continued... and continued... and continued, stretching into a depth that made no spatial sense.

Belobog itself could be encompassed within his shadow sense with ease.

This space exceeded that.

A cold sensation crept along his spine, equal parts awe and unease, as the implication settled in. Either the underground complex extended far beyond anything physically possible, or it had been constructed using principles that warped conventional geometry. Neither explanation inspired confidence.

Sunny swallowed, suddenly aware that for once he might be slightly out of his depth, which was frankly rude of reality to spring on him without warning.

’Well, that’s probably fine. Clara’s a good girl, right?’

He approached the front door and knocked. 𝙛𝒓𝒆𝙚𝒘𝒆𝓫𝙣𝓸𝙫𝓮𝒍.𝒄𝒐𝓶

The moment his knuckles made contact, the mansion woke up.

Panels slid aside with mechanical precision, revealing an array of scanners that unfolded like the petals of a very invasive flower. A beam of light swept across his face, pausing on his eye long enough to map it in excruciating detail, followed by a thin needle that darted forward with surgical speed, pricking his finger before he could react.

A bead of blood welled up.

Instinctively, Blood Weave surged, attempting to retract the lost fluid back into his body, but the droplet hovered in midair, held in place by some unseen field before being siphoned into a micro-container that sealed with an audible click.

Sunny stared at his finger, deeply offended.

Another device extended, plucking a single strand of his hair with delicate efficiency before retracting just as quickly. The panels closed, the mechanisms vanished, and the door swung open as though nothing unusual had occurred.

He remained standing there for a moment, processing the fact that something had just overruled one of his Attributes without asking permission.

’So marketable...’

Sunny tried and failed to resist the urge to participate in child labor.

If Clara could neutralize Blood Weave on demand, the other areas she could develop in were likely endless. He briefly imagined auctioning the technology to the highest bidder and retiring on a private asteroid made entirely of luxury goods, then dismissed the fantasy as impractical since it would require interacting with people who had both money and expectations.

Inside, the mansion felt larger than it had any right to be, hallways branching into new wings lined with reinforced doors and softly glowing panels. The decor remained unmistakably Clara’s, warm fabrics and simple furnishings offsetting the industrial elements, but there was a subtle shift in tone, an undercurrent of purpose that had not been present before.

Sunny wandered through the corridors with casual curiosity, whistling a tuneless melody that echoed faintly off the walls. He checked rooms at random, poking his head inside laboratories filled with equipment he did not recognize, storage areas stacked with neatly organized components, and living spaces that suggested the automatons now maintained permanent indoor stations rather than roaming outside.

Eventually, he stopped trying to find her the normal way and let his shadow sense do the work.

Two human presences registered deep within the mansion.

One radiated the unmistakable density of a Transcendent, the other the slightly lighter yet still formidable presence of an Ascended. Clara and Seele, then, which meant he had arrived at precisely the right time to dramatically interrupt whatever they were doing.

Grinning faintly, he made his way toward them with exaggerated stealth that fooled absolutely nobody.

As he approached the final door, something about the shape of Clara’s shadow made him hesitate. It was... wrong. Not hostile, not corrupted, but unfamiliar in a way that suggested a change in shape.

He dispatched Gloomy through the gap beneath the door, borrowing its perception for a quick reconnaissance.

What he saw made him blink.

Then blink again.

Finally deciding that confusion would not resolve itself without direct confrontation, he opened the door and stepped inside.

Seele stood near the far side of the room, posture relaxed but alert, one hip cocked slightly as though she had been mid-conversation before his arrival. Ascendance had refined her in the way a master sculptor refines marble, sharpening lines that had once been merely attractive into something striking enough to command attention. Her dark violet hair flowed in layered strands that caught the light with subtle iridescence, framing a face that balanced softness and ferocity in equal measure. Her eyes, luminous amethyst edged with a faint inner glow, tracked him immediately, intensity sharpening as recognition set in.

Sunny’s gaze dipped automatically.

Her butt did, in fact, look more appealing than he remembered.

Even more impressive, her waist was almost as small as his own.

He mentally congratulated her on the upgrade before turning to Clara.

Or rather, to the person who replaced Clara.

Gone was the small, timid child who had clung to oversized clothing and Svarog’s protective presence like a lifeline. In her place sat a young woman who appeared roughly their age, her once-short white hair now grown long and gathered into a voluminous ponytail that cascaded over one shoulder like spun snow. Her crimson eyes retained their familiar color but not their innocence, holding a calm, assessing intelligence that felt far older than her apparent years.

She wore a dress that blended practicality with quiet elegance, layered fabrics in muted tones that complemented her pale complexion while allowing ease of movement, though she still wore her red coat, which fit her much better now. The timid posture had been replaced by poise, her back straight, shoulders relaxed, one hand resting lightly on a teacup as though she had always belonged in positions of authority.

Commanding beauty was the only phrase that came to mind, though Sunny would never admit to thinking it out loud.

Both girls turned toward him simultaneously.

Sunny chuckled awkwardly, suddenly aware that bursting into a room unannounced after months of absence might not qualify as impeccable social etiquette. He shuffled sideways toward Seele, seeking familiar territory, while she continued to stare at him with unnerving intensity, her gaze sweeping from head to toe as though cataloging every change Ascendance had wrought.

He leaned down and whispered conspiratorially, breath tickling her ear.

"Hey, long time no see... so, when exactly was I supposed to know that Clara had a bombshell older sister?"

Seele did not hesitate.

Her elbow drove into his ribs with surgical precision.

"That is Clara, you idiot."

Sunny blinked.

His brain processed the statement, rejected it, reprocessed it, and then finally accepted the horrifying possibility that she was not joking.

He slowly turned back toward the girl at the table, who regarded him with serene composure, one delicate brow lifting almost imperceptibly as though awaiting his reaction with mild curiosity.

Sunny cleared his throat.

"Right. That explains... nothing, actually."

Regret arrived exactly one second after his earlier comment replayed in his mind.

Calling someone a bombshell was significantly less charming when that someone was a child you had previously met while she was hiding behind a robot. He resisted the urge to dig himself a deeper hole by apologizing, since apologies implied accountability, which he preferred to avoid whenever possible.

Clara — or whatever version of Clara this was — set her teacup down with gentle finality.

She spoke, her voice familiar yet matured, the soft hesitancy replaced by quiet confidence.

"It has been a while, Sunny. I was wondering when you would come."

He stared at her, still trying to reconcile with reality.

’Wait, no, none of this is important. Why the hell is she taller than me?!’