An informal accusation of sabotage would be enough to send a Citadel into a low, scurrying, paranoid frenzy. The lead tech in charge of a test exercise filing a formal suspicion of conspiracy ranked a few steps higher.

Anyone below the rank of Sergeant or Senior Technician was confined to quarters. Anyone below the rank of Gunnery Chief or Supervising Technician, subject to stringent restrictions. No leaving the Citadel, no receiving or sending any sort of mail or communication, and subject to constant surveillance at all times. No exceptions.

Aria was responsible for all of the discomfort. If the lockdown were unjustified, she would be held to task for it, both directly by the strictures of the Imperium's Admiralty and the indirect "Frontier Justice" of her peers.

Unfortunately for quite literally everyone, the forensics team had found what she'd suspected. Someone had sabotaged the isolator gaskets, dusting them with cobalt. In regular inspections or electrical diagnostics, everything would appear normal, but in the extreme conditions of firing the cannon, the cobalt would magnetize, and the gaskets turned into something closer to secondary coils. It really was ingenious. If it hadn't almost blown up a piece of vital planetary defense infrastructure, maybe Aria would even find it within her to give some grudging kudos to whoever thought of it.

As it was she mostly just wanted to strangle them until they started turning pretty colours.

Still, she was a Supervising Technician, and she had directly prevented the Dawnbreaker from slagging itself due to a lapsed containment field, which left her largely unsuspected as the culprit, and consequently unrestricted by the lockdown. Any guilt she may have felt about that quickly evaporated in the face of the realization that this meant she had the training deck all to herself.

Being a technician, Aria was not technically required to practice combat skills. While it was certainly desirable, non-combatants had no obligation to maintain their marksmanship, nor to participate in the numerous competitions held among the various divisions of the Admiralty. Nonetheless, she found a certain meditative quality in the practice, a bare catharsis that seemed to strip away all the world's worries and leave only her, her weapon, and the rhythmic satisfaction of hitting her targets.

Having her name practically burnt into the top of every leaderboard on Astra-V was just a nice bonus. Incidental, really.

And all the cash prizes certainly helped the pill go down.

Technicians weren't issued service weapons, but this far from the heavily-defended core worlds, where a border skirmish or good old fashioned banditry could kick down one's door any old day, people damn near learned to shoot before they learned to walk.

Most people would consider any sort of vaguely tubular object that could lob metal needles with at least some kind of consistency to suffice for their needs. Aria had a slightly more discerning palate.

The Tenet was — or at least would some day be — Aria's magnum opus. An elegant (if at times…industrious) marriage of various bits of scrap and spare that she'd managed to scrounge with tooth and claw over the years. It was an ingenious marriage of the old and the new: the firing mechanisms of a decommissioned "Vigil", the standard service rifle of the Amber Imperium's soldiers, combined with a custom "scrap" chassis made from salvaged battleship hull plate, and a short-stroke gas piston for self-loading, with a primitive straight-pull manual bolt for overpressure ammo. Of course, "decommissioned" really meant "taken off a corpse", but such indignities came off just the same in an ultrasonic bath.

The part that most people would immediately recognize as being worth money — and then promptly try to rob her for, before getting their faces smashed in — was the barrel. Monocrystalline polyrifled barrels were a core world exclusive, and even "decommissioned" articles fetched an eye-watering price that few would be willing to front. Still, for precision marksmanship, they had few peers, and in terms of tolerance for high-wear usage, they were without equal.

Barrels could be replaced though. At the end of the day, even with a cheaper barrel, with worse rifling, that wore faster, Aria Rostova-Chen would still be Aria Rostova-Chen, and she would still humble anyone who thought they could show her up. The true crown jewel of the Tenet was its Injection Core. Sintered ceramic nozzles tied to a precision mixing valve, controlled by an onboard fire control computer that allowed for the two-part hypergolic propellant mix to be sprayed into the firing chamber with nanoliter precision, igniting instantly to propel a standard 6.5mm tungsten penetrator dart at 2 kilometers per second, at max volume.

Granted, the force of that would probably also break her shoulder if she ever used that much, but it was comforting, knowing she had the option.

Aria loaded a training program onto the deck. Technically not an officially sanctioned one but, once again, if she wanted to sabotage something, someone of her standing had better and cleaner ways of doing it.

This program was an old favourite, a semi-custom. She'd found it on the Internet, years ago, ostensibly a leak from some minor upstart cultivator sect that got too enthusiastic in its encroachment and was summarily annihilated for its boldness. Supposedly, it had been a training exercise for their initiates, a fictitious "Reactor Core" breach scenario. The scenario's rules were brutally simplistic: reach the core, stop the cannon, and don't eat a bullet on the way.

She'd made some tweaks and modifications over the years. The original had been set in a ship, for example. As Aria stepped out into the active area of the training deck, the walls that arose all around her weren't the armoured alloy hulls of a freight barge, but the vitrified regolith walls of a Sentinel maintenance tunnel — this one had been based off of Northwest #5, "Starfall". The strobing violet emergency lights though, were some kind of awful inescapable Imperium standard.

The premise of the scenario was fairly elementary. Some vague, undefined hostile force was in control of the cannon's power source. To win, all she had to do was make it there and prevent the cannon from firing, and not kill any non-combatants along the way. A perfectly suitable combat training exercise for unawakened initiates of a minor sect.

Hence the modifications.

The first change, and the earliest, had been to change the layout from deterministic to procedural. Every new iteration would have a different set of corridors, different numbers of non-combatant techs and enemy infiltrators, and different placements for them. No cheating by just memorizing the course.

Aria took a brisk pace down the tunnel, Tenet shouldered, one eye against the hyperspectral optical sight, the other wide open to her surroundings (a lesson she only had to learn once, even if acting on it required getting shot a few dozen more times). A clock ticked down in her head. That was her second alteration; the cannon would fire after a randomized time, within a semi-random range, preventing her from gaming a deterministic clock or slowing her pace any more than absolutely necessary.

Movement at the end of the hall. Someone turning the corner. The assessment took a fraction of a second. Technician's exosuit, but no biometric ID slate on the left breast, and a weapon holstered at the hip.

Aria's thumb pressed down onto the trigger paddle atop the receiver without a moment's hesitation.

CRACK

A sharp, thunderous report, matched by the bright jade-green muzzle flash.

HISS

The vapours of inert propellant byproducts vented out of the sides of the weapon.

thump

The target dropped dead at the end of the hall without even time enough to draw its weapon.

Aria took only a passing moment to inspect the map on the wall, memorizing the shortest route from her location to the core. Of course, the shortest route would also be the most densely-guarded one.

Once, that might've intimidated her. Now, it was simply exhilirating.

She kept a brisk, unwavering pace down the winding network of tunnels leading to the power station. She turned a corner. Three targets. One non-combatant.

Aria strafed across the corridor. CRACK-hiss-thump and one of the attackers dropped. The other drew its weapon, and she quickly ducked down into a narrow side tunnel — a maintenance passage for coolant lines — as bullets whizzed past her head. The clock in her head ticked. That was a time loss. She should've taken them both out before either of them got their weapons drawn. Sloppy.

Aria slid out from the narrow tunnel, her stance low and her body low to the ground. The remaining attacker was using the technician as a human shield, holding its weapon against the hostage's neck. The behaviour was a relatively rare emergent mutation of the target AI, causing it to interpret "using its environment" as "using other targets in its environment". Novel, and useful enough to her training that she'd seen no reason to try to get rid of it, but an undeniable pain in the ass.

Aria didn't take her thumb off the trigger as her fingers worked the dials on the side of the rifle, altering the propellant pressure and muzzle energy in real time. No need to look; the dials were etched with tactile readings, optimized to be read with one's fingertips.

Her thumb squeezed.

CRACK-hiss

The tungsten dart blew threw the target's weapon faster than the trigger could've possibly been pulled, shattering it into spall, then kept going and severed the vertebrae in its neck.

She put a second round through its torso as she walked past. Not strictly necessary, but it was the principle of the thing.

Aria slowed for a moment as she reached the corner of the final corridor. According to her mental clock, she had 20 seconds left, at worst. This last push would be the most dangerous. They knew she was coming, which meant that by the probabilities of sheer volume of fire, failure was all but assumed.

Aria turned the corner. Time did not slow to a crawl, as nice as that would've been. In fact, both her internal clock and her external perceptions proceeded apace. Thankfully, her mind and her hands more than kept said pace.

Be it a sky-rending Sentinel or a child's plinking gun, the principles were all the same. It was all just ballistics. There was a firing solution for every firing problem, if you were smart and fast enough to find it.

Aria strafed diagonally, eyes forward, shoulders locked, hips unmoving. The variables had been set. Execution was all that remained. 12 enemy combatants. All heavily armoured. Her fingers moved deftly across the dials on the side of her weapon, turning the muzzle energy as high as she could without injuring herself…too badly, at least.

CRACK-hiss

A turn of her hips.

Three shots rang out legato. The tungsten darts punched through the armoured bodies as though they were barely even there, one after another, until half the targets were eliminated.

She didn't stop long enough to let the bodies hit the ground. Every second was precious, every step preordained. She would move forward, unerring in her aim, and if her skill was insufficient, she would simply have to do better next time.

Her gun jammed.

For just an instant, Aria's mind hitched. Tenet did not jam. It simply wasn't a thing that happened. She'd once set up an autotrigger to put 10,000 rounds through it, and not a single one of those rounds had caused a jam. Guns she made, guns she designed, guns she worked on and maintained, did not jam. They did not malfunction at all.

Not unless someone was sabotaging them.

She dropped her rifle, and reached for the nearest target. While most things in the training program were holograms, the targets and their weapons did in fact physically exist, even if they might look a little different in truth.

Seven simultaneous clicks. Jammed. Every single one of them.

Someone was tampering with the training simulation.

For some reason that was by now long-forgotten, Aria had given every single one of the assailants in the simulation batons as backup weapons. The training program would only stop on a hit perceived as lethal, which meant that barring any knocks to the head or throat, those batons could rain down on her like heaven's fortune, and she would suffer every single one.

She decided, quite calmly, that she would be promptly defenestrating whoever was responsible. She didn't care if it was the Deputy Vice Admiral himself, they were getting thrown out of a fucking window.

17 seconds left on the clock, at worst.

12 seconds to reach the end of the corridor.

6 assailants.

2 seconds each. That's all she would spare.

Her opponents weren't polite enough to all line up to get their asses kicked, unfortunately, but then people seldom were. She always made it work regardless.

Aria was physically unremarkable. Not very tall, not particularly strong. Overwhelmingly average in most respects. Any fighting style that relied on hitting harder than your opponent would see her faring poorly against half her matchups.

So, naturally, she'd found one that relied on your opponent hitting harder than you could. It was all numbers, at the end of the day. If a path to victory was calculable, the day could be won.

That didn't mean it wouldn't hurt like Hell on the way there, though.

Three batons arced down towards her all at once. She wasn't a cultivator, not yet, not in spite of her best efforts. She was neither physically nor mentally fast enough to defend against every single one. She'd have to pick one and just eat the rest somewhere that didn't end the simulation.

The heel of her palm struck at the wrist of the closest assailant, with sufficient force to disarm. At the same time, her foot struck at the side of its knee, throwing it off-balance. Two extremely rigid, shockingly heavy batons landed on the side of her ribs and on her back with bruising force, damn near knocking the wind out of her lungs.

Aria grit her teeth through the pain, slamming her boot into her attacker's torso, sending it careening backwards.

In the close confines of the relatively narrow corridor, launching someone ass over teakettle had a significant disorienting effect on the crowd. Not quite sufficient to eliminate her opponents, but that was fine. She didn't need to eliminate them.

15 seconds remaining.

All she had to do was get them out of the way long enough to make it to the end of the hallway. Through the door, press the button. Complete the exercise.

Another baton arced down towards her, but this time she wasn't particularly inclined to just take it: she struck out with another palm heel strike to the wrist, followed by a crouch and a leg grapple, tugging the target straight to the floor. Perhaps someone stronger than her could pull off a bona fide leg sweep, but every time she'd tried she'd just ended up with bruised legs.

Aria rolled forward, using her hands to cushion her skull against the hard ceracrete floors of the training deck, rising up out of the crouch. Two attackers left — at least ones who still presented a meaningful opposition between her and her objective — one on either flank, both swinging at her. A simple arithmetic problem, really.

Simply cancel the terms on either side.

Aria lunged at the one on her left, grabbing it under the armpit and groin, and leveraging her entire upper body to toss it at its compatriot. Once again, it was insufficient to actually eliminate them — even if making the poor sack of potatoes eat the hit meant for her was a decent consolation prize — but that wasn't the point. She was free and clear for the final stretch of hallway.

Aria sprinted through the door at the end of the hall — dimly remembering how actually they would be called bulkheads, since they were part of an Admiralty weapons installation, and how not caring about the distinction supposedly made her unqualified for the rank she held — and didn't even bother stopping as she hit the big, obvious, red E-Stop button.

Aria glared daggers at the blacked-out windows of the observation deck, as she leaned on the now-unveiled ceracrete wall, catching her breath. "That was pretty close time to my personal best, so I'm not too mad. I'll give you a five second head start before I chase you down and spit in your ears."

The dark glass turned transparent, and Aria's throat ran dry as she practically felt the blood drain from her face. On the other side, grinning lazily like the Cheshire cat, stood a woman who time didn't dare to ravage. Her hair was ashen gray, not from age, but because she simply believed it ought to be. Her physique was soft, rounded, almost gentle.

Her eyes were anything but.

They bore into Aria, the weight of centuries, of infinite lives weighed and altered irreversibly, of profound truths grasped and of countless foes whose mettle was tested and found wanting.

The woman was dressed in simple robes, charcoal black, with skeletal red streaks embroidered into its surface. An amulet sat upon her breast, a gilded cage shackling a blood-red crimson gemstone trapped within. At her waist, sheathed within a gold-and-red sash, sat a pair of stone knives, knapped from a pale jade.

The woman was an Inner Disciple of the Sacred Starheart Monastery. A venerable immortal who had withstood the wrath of Tribulation, and been found worthy to carry the will and the marque of the Monastery's ancient and unknowable elders.

She spoke, with a voice like honeyed snowflakes, and Aria found herself wondering if perhaps death would be a kinder fate.

"I would so very much like to see you try that, little firebrand."