This was originally intended to be part of the "Six Shades of Ruin" project (which I haven't forgotten and will be updating!), but it got a lot longer and seemed set on being its own story. Hope you enjoy! Concrit, as ever, is greatly appreciated!

"...so then I heard-" Castiel's voice cut off as the building thrum that had underlain his words peaked, and the lights of the hall faded into pitch blackness. Voices cut through it, seeming to come from every direction as they echoed one another in confusion and fear.

"Ow!" "What happened?!" "What's going on?!" "I can't see!" "Moon's Light!" "Where are you?!"

"Silence!" a woman shouted into the growing panic, enough authority in her voice that the majority obeyed the order. Castiel listened to the hush, his unease growing. Something was very, very wrong. He only realised what he'd missed as it began again: the faint, undying background vibration, more felt than heard, that spoke of the life of the city. For that brief time, Soltis' halls had rung with confusion, but the city itself had fallen utterly silent. Blue-white light traced circuitry patterns along walls, floors, and ceilings, and the soft illumination of the city's internal day sprang back to life. The cool light revealed the turmoil wrought by the seconds of darkness, ordinarily calm people frozen mid-stride, or fallen to the floor, or clutching at the walls – or even one another.

Glancing at his companion, an engineer a couple of ranks higher than Castiel himself, he asked

"What do you think that was all about?"

Meredin shrugged. "It can't have been our doing, but we should get back to the Core and find out just what did cause it."

The Core was the local engineers' nickname for the immense Silver Moon Stone that had been a part of the continent since time immemorial, painstakingly excavated from rock and earth and purified in situ through tremendous effort. Much smaller than its former self, it held if anything more power than it had before, resisting the pull of Arcadia's gravity and powering a section of the city with energy to spare.

"You're right! There weren't any kind of tests scheduled for today, were there?"

A headshake. "Not that I know of, and nothing we've done has ever caused something like this. I can't think of anything that could have. Better get down there before something worse happens and we both get demoted back to Tenth."

"Ouch," Castiel said, with feeling. He was a fourth-rank local engineer, and Meredin a second, just one rank below the First Engineer who oversaw all work to do with their particular Core. They'd both earned their positions by their own merit and nothing more, like all Silvites, at least in theory. But a catastrophic failure would see them damned for their own incompetence unless there was no way they could have prevented the disaster.

"You!" a voice rang out as they turned back the way they'd come, close by and definitely female. Startled, Castiel stopped dead, looking back over his shoulder to see a woman closing on them rapidly. She was wearing a long-sleeved white dress that left her shoulders bare and split a little below her hips. Decorated in places with a silver circuitry pattern, together with a silver headband, the style of her clothing and tone of her voice told the two engineers that she was someone technically more important than either of them, although not directly related to their line of work.

"You're engineers, aren't you?"

"Er... that's right, ma'am." Like hers, Castiel's and Meredin's clothes gave away their position in life quite well. There was a lot more light grey in their somewhat simpler outfits, its thin, soft weave belying its prowess as an exceptionally damage-resistant and insulating fabric. The exact detailing and patterning of the clothing denoted their precise status, for anyone who was interested enough to care.

"Do you know what just happened?"

She wasn't demanding they tell her, although he suspected a part of her wanted to, and that, at least, was good. A lot of people expected all engineers to be able to solve anything, instantly, and while they were good, they weren't that good.

"No, ma'am. We were about to start back to the Core – that's what we call the Stone here, Silver Source Thirteen – to find out."

"Good." She scrutinised them for a moment. "Fourth and Second rank Engineers? End of your morning shift?"

Startled, Castiel nodded. "That's right, ma'am."

"You'll take me there with you."

Castiel blinked at the abrupt statement. "What, to the – to Silver Source Thirteen, ma'am?"

"Yes, unless it isn't permitted for me to view the Source."

"No, there's no rule against it, but..." He let himself trail off. Dissuading her would be more trouble than it was worth with whatever had just happened still hanging over their heads, and as long as she'd stay out of the way – which he'd expect her to be able to; few people rose high without a level head on their shoulders – then she wouldn't be much of a problem.

"Good. Lead on, then."

The two engineers started walking again, sharing a quick glance that spoke more than any words they might have exchanged.

"Now that's sorted out," she said, falling into place behind them, "we should introduce ourselves. I'm Celesia."

Castiel and Meredin responded with their names automatically before something registered in Castiel's mind, prompting him to speak and cut her off.

"Ple-"

"Celesia – not Sector Prime Celesia?!"

"Er... yes, actually."

He looked over his shoulder to see her looking slightly uncomfortable at his outburst, and turned around, now walking backwards with practised ease, to look at her again. Celesia's hair was dark for a Silvite, but still recognisably blonde rather than the foreign light brown, and her eyes were a brilliant green that Castiel had known his sister envy. Soltis was divided into six sectors both physically and politically; seven if the Elders' Spire was considered as well. The Sector Primes governed the six sectors, and in turn answered to the Elders, who also oversaw the Primes of other cities. Soltis was simply the largest Silvite city, and the capital.

Celesia covered a smile with a slender hand, but Castiel could still see it dancing in her eyes. This close to, he wondered how old she was. Silvites lived a long time, the average lifespan of a Soltisian noticeably longer than any of their less advanced cousins beneath the other Moons, but she didn't look all that old.

"You should be more careful, Engineer Castiel. You can't see where you're going."

Despite himself, he found himself wanting to smile back at her light tone. "I know my way around well enough, Sector Prime. If we have to make repairs in the dark, I'm well prepared."

She chuckled, and beside him, Meredin laughed.

"Hey, don't youuu-!" The entire city trembled, a crash as much felt as heard rolling through it, and Castiel fell backwards to the floor. Marginally more stable, Meredin managed to keep his balance, and Celesia clung to the hall's central divider for support.

"That was an impact on the Dome of Light!" she exclaimed, shocked. Propping himself up on his elbows, Castiel stared up at her, disbelieving.

"An... an attack?"

Another impact sent its shockwave rippling faintly through the city, and his eyes widened further as Meredin shouted "Sabotage!"

At once, everything fell into place. The unprecedented power fluctuation – somehow, something or someone had infiltrated the city of Soltis, and their army was attacking from the outside even as unknown agents within attempted to disable the power sources for the Dome of Light!

"They must have meant to disable our power and attack when we couldn't defend ourselves!" Celesia shouted, echoing Castiel's own thoughts. "But they didn't count on the strength of our defences – or our engineers! They won't underestimate us again!" She extended a hand to Castiel, who took it automatically, letting her help him up. "Second Engineer Meredin, head back to the Source, to your Core! They'll need you! Fourth Engineer Castiel, stay with me!"

Neither of them thought to argue, Meredin nodding and dashing off, keeping his footing even as a third tremor shook the city.

"What are they doing?!" Castiel exclaimed. He'd experienced several such attacks, and often all that could be made out from inside was a dull booming in the outermost two or three levels of the city. Only when the Gigas Bluheim and Plergoth had been brought to bear on their defences had anything like this happened, and so far they were the only ones to have attacked them directly. Bluheim had retreated unharmed after carrying out a lightning-fast strike that had shaken the populace but caused little damage, but Plergoth only when the Gigas itself had been wounded by a cleverly programmed drone.

"I don't know... a Gigas?" She started moving as she spoke, running on down the hall. The orderly flow of Silvite life had been utterly disrupted, and people were trying to go in all directions on both sides of the hall, with the result that they were creating tangled knots of confusion everywhere. Castiel followed her, pushing people aside where he had to, fighting to keep the determined Sector Prime in sight and within reach. "The Blue Gigas' appearance two months ago was designed to test our defences. It must have been. Perhaps this is their real attack!"

It was the best theory either of them could come up with. Celesia stopped at the first public terminal, Castiel almost carried past her by a sudden flow of people. Quickly providing the authorisations appropriate to her station, she convinced it to display an external view of the city, panning the camera up and around to angle it towards the Dome of Light and the invading fleet she expected. But only plumes of smoke marred the sky, as if several ships had fallen in battle, too few for a fleet yet leaving none behind, either fleeing or fighting.

"Look at the roof!" Castiel shouted, peering over her shoulder. Obediently, her gaze dropped to the bottom of the screen, and she gasped, panning down again. The broad and roughly level expanse of white that formed the roof of whichever section of the Sector she'd accessed was dotted with defence drones, floating automatons that policed and protected all Silvite cities. Normally, the larger units would be mobilised outside the shield to fight off attackers, but now robots of all sizes mingled, seeming to almost crouch against the city as if afraid.

"What are they hiding from?" he asked. Celesia had no response, beginning to aim the camera up again as the city rumbled once more, and Castiel grabbed her arms to stabilise both her and himself, only really becoming conscious of his action after the shaking had died. At once, he let go again.

"I'm sorry, Sector Prime!"

"It's all right." She shook her head. "They're dropping something on us, but I can't make out what. We've got to get onto the surface."

"To the surface?!" Castiel knew people who had never been above ground in their lives. Soltis provided everything they could possibly need. In the middle of an attack, he'd feel safer by far with its familiar ceiling above his head than he would protected solely by the immaterial Dome of Light.

"Yes, the surface! Traffic won't be permitted to fly, and after what just happened to the power I don't trust the teleportation system. I need to know what's going on out there, and the only way I can do that now is to get aboveground and see for myself!"

Reluctantly, he nodded.

"Now show me the nearest way up that doesn't involve the city's power!"

That, in Soltis, was a lot harder than it sounded. Almost everything relied on Silvite achievement one way or another, each generation building on the work of that before. Each one left a small addition to the vast legacy that was Soltis before their lives were over and they returned to the empty void of death. Knowing by the very nature of their innate magical gifts that there were no second chances, that life departed into the same void from which it so miraculously came, it was their philosophy to make every second worthwhile, and often to leave at least something that would live on after they themselves had returned to nothing. It had driven them on, further and faster than the other civilisations who wasted their one chance at life, or let their talents lie idle, expecting some other fate beyond death's blank and inescapable embrace. Castiel was forced to pause through several seconds, and two more impacts, before replying.

"...This way!"

He couldn't help but worry as he took off down the corridor. Was it his imagination, or were the attacks growing closer together? The Dome of Light could only protect them as long as it had power, and if there was another blackout, they'd be defenceless. Even without that, he knew that however magnificent it was, the defensive barrier had to have its limitations. It had never been tested to destruction even by the Gigas, and its theoretical strength was claimed to have been specifically calculated to withstand truly astronomical impacts, but even so, as an engineer he knew how disastrous it could be to assume anything was limitless.

Several more distant impacts sent ripples through the city before they even reached the stairs, and Castiel groaned as he realised they'd have to climb the entire twenty-three flights unaided.

"Are you sure about this? It's twenty-three floors to the top!"

"We don't have a choice, Engineer. I don't have a choice. If you want to, go back to Source Thirteen."

It was tempting. Very tempting. The Source would be providing a lot of power, and whatever had happened to it would have left it needing careful monitoring even if it were repaired. Though everyone would doubtless be there already, there would be a place for him, and he'd be welcomed unquestioningly. But however much he wanted to hide in familiarity, he knew he couldn't leave the determined Sector Prime entirely alone.

"I'll see this through, Sector Prime."

"Good. Then come on!"

She started taking the stairs two at a time, Castiel trailing behind, going faster than he felt comfortable with but still slower than she was. Only when a powerful shudder caused her to lose her footing and trip, sliding down several steps before she could catch herself, did she slow, and then only as much as she had to.

By the time they reached the top, both were out of breath. Celesia bent double, gasping, for several moments before forcing herself to straighten up and open the door to the outside world... revealing a scene neither had ever imagined even in their wildest fears.

Trails of smoke angled across the sky in unbelievable numbers. It wasn't Soltis that was under attack, but the entire continent – no, further than that. Nowhere could Castiel see an end to the streaks of darkness, growing thinner only with distance and continuing into the horizon until they became indistinguishable from one another and from the wounded sky.

"How are they doing this...?" he breathed, and beside him, Celesia clutched his arm in the first indication he'd seen that she might not be completely self-assured and in control.

"They're not..."

He looked at her white face, and followed its angle up until he, too, saw what she did and he returned her grip with one equally fierce.

"It's the Moon..."