Imagine sucking air into a pair of lungs. The stem that the air passes through may bulge from one end of the corridor into another, but it is never altered drastically beyond its original proportions. The true change occurs around the lung sacs. As more and more oxygen and nitrogen are pushed into a space too small to accept the accumulation, there is only one thing to do: expand.
So long as internal pressure increases, volume must as well, and that's what the Gaiss Hollow looked like. The lung of a giant expanded to the point of breaking, and then some. This giant--metaphorically, of course, had long expired and returned to rest in stone. Its lung, petrified and slowly reclaimed by generations of moving sediments and pressure, now made a subterranean world, the only one Pa-5 had ever known.
She turned back to her guide, saluting as the scutumsteel was rolled back into place, collapsing back into the valley wall. He returned it, and in his eyes she saw the same look all the other guides and assistants had given. It was cut off like before, too.
She had been brought out at the bottom of one of many crevice-like valleys that dotted the landscape around Fort Io, a signature quirk of the western lands. She clicked off the headlights, guided by a dim, yet passable bioluminescent glow emanating from the local flora. Mosses were just about the only thing that could persist down here, latching onto the valley basin with a determination to survive rivaling cockroaches. She had once heard of a kind of plant called a flower, and it was described as beautiful and otherworldly.
The path on her HUD flickered, then rerouted as she turned, disappearing beyond the local mists. She proceeded cautiously at first, unsure if there were any Aud that had skirted around the base as an advance hunting party. Most would've headed east, attracted by the larger amounts of people in the capitol and Fort Rhea.
Her steps were raggedy at first, making her cringe every time she stumbled against a rocky cropping and almost face planted. Even if the light WAVs were made for maneuverability and speed, they were a far cry from the fine motor control and capabilities of her body.
With every meter, she adapted, relying on both her HUD and the automated servos to find a delicate balance between speed and consistency that brought her to a comfortable pace.
With most of her attention occupied, she cranked the audio sensors past their recommended settings and chose her ears as the lookout. Each footstep was a deep bass thump against her eardrums, and at this level, the distant ongoing assault against the fort was still audible. Mostly the war cries of the Aud, but the retort of sonics and electronics made a decent effort to accompany. Together, it was a macabre tone of harmony and melody.
Every few seconds, the frequency of man-made sounds decreased, reminding her of the timer over her head, ticking with ceremonious indifference. Some of the shock from the attack had been pushed out of her mind, but it was still too much to make peace with at the moment.
There had been drills, she mused. With two forts already nothing but history and ruins, it was never a matter of if, just when the Aud would target another fort. A rarer, yet perfectly viable outcome was the bypassing of the forts entirely, and the sitesmen only learning of the fall of the capitol days after communications had ceased. She supposed it was better, infinitely better that another fort had met its end, instead of the capitol. So long as the final city of humanity stood, there was a chance for rebuilding, repopulation, and the eventual counterstrike against the Aud. If the Last Beacon fell, so would their last hope for the future.
Her journey became primarily vertical as she reached one end of the valley. She stumbled as a pothole hidden by moss attempted to claim a leg, bracing against a rock wall for support. The HUD beeped, and to her chagrin, she watched as the dotted line rerouted again, directing her up and over the wall. Good thing she was sent off in a light WAV.
The number of handholds needed to make a quick path up wasn't absent, just scarce enough that she had to make a few risky maneuvers. Her knuckles punched deeper into the stone whenever it wasn't enough, and the only time she had to jump, the fear of being reclaimed by gravity was strong.
"When I get home--" Right. She couldn't get her hopes up and risk making a mistake, especially not here. It was if. If she made it home, not when. The last step was another leap of faith, something she did with hesitance.
But the suit didn't fail her, providing a reassuring lack of error in its movements that she wasn't sure her arms possessed. She dragged her torso and legs over the top, stopping to take a breath and look over the edge. The valley was further down than she first thought, giving credence to her unwillingness to risk speeding her climb.
The HUD's track flashed, informing her of an emergency change in course. Someone further along another path adjacent to hers had sent out a transmission. She wondered if it was someone she knew, pressing her knees into the crumbly sediment to stand.
The base level of Gaiss Hollow was an impossibility. Stretching hundreds of kilometers in every direction, it was as if a great plain was ripped from its place and dragged into the depths. Capitol scientists had long puzzled over how it was vast enough to have extensive airspace and hadn't collapsed under the weight of the cavern roof without support but were without an answer.
Like the valley, the craggy ground itself was nearly imperceptible beneath the blanket of mildew and fluff that refused to budge even as Pa-5 stepped through it. It swirled and coasted around, but her job was made easier since it never went higher than her thighs. Or, the WAV's thighs, at least. It'd be up to her waist if she stepped out.
There were less mosses up here too. Or any plant life, really. The path continued on and on, and despite her reservations, Pa-5 slowed her pace. The suit battery was down three percent, and unless she wanted to see the meter drop lower, she needed to get conservative.
Once out of the immediate vicinity of the valley, she halted long enough to deposit a cluster of stands. Like three-legged dogs, each uncurled and began wobbling in a different direction at a respectable speed. Inside her helmet, she watched as additional feeds buzzed alive on her HUD.
The scout drones were built for endurance, with a large enough internal volume to hold a suit battery of their own. The vastly smaller number of functions that needed to be powered meant the drones could continue running days after her suit's power source ran dry.
Two were directed back towards the fort. One returned to the valley, waiting at the top of the ridge to warn her if she was followed. Three went ahead of her in a pronged formation, the one in the middle heading straight along the HUD's path. And two more went off in the opposite direction, toward the Last Light. She expected the ones assigned to check the situation at the fort to encounter Aud first.
Two kilometers along the path, an alert sounded. The fifth feed took primary residence on the bottom corner of her HUD. It belonged to the drone headed for the northwest, a good seven kilometers from her. Capturing some vague motions, the program controlling the scout switched to thermal scanning. It revealed a trio of hazy, red blotches crowded around another smaller blotch.
She must've passed the threshold where the technicians working under Fort Io could alert her of a sacrificial engineer's expiration. Or the fort had been entirely overrun. Whatever the case, Pa-5 took manual control of the drone, directing it to change its course back east. She needed to see the number of Aud heading west, in her direction.
While she covered more ground, she continually cycled through the feeds, instructing the drones to inform her of the detection of any abnormal movement or heat emission. It wouldn't hurt to get a location on any of the surviving engineers. One of the eastern drones past the fort encountered another drone model, this one active, but unmoving. It had stopped receiving commands from its deployer, she guessed. Did it belong to the pilot her west-most drone detected?
The trio of drones she sent back to the fort had arrived. She directed one to check the northern and southeastern perimeters each, while the last was sent into the fort itself. The walls were still standing, but they had been so damaged it was a miracle they were still perpendicular to the ground. The drone steadily climbed up and over, and she was greeted with the scenery she had morbidly anticipated: smashed and collapsed units, bodies left, right, and center, and an unequal proportion of human to Aud bodies. A good chunk of stragglers was left, gorging themselves on the bodies of both sides. Humanity knew the Aud practiced cannibalism, but the ferocity at which a group of orange tore into the flesh of a dead yellow upset her stomach.
The drone utilized anti-grav propulsion technology to leap from the wall to one of the adjacent units. She wanted to get a fuller picture before risking the drone.
The defensive lines guarding the garage had been whittled down to two lines of WAVs and turrets, doing their best to hold the accumulated horde back. They were using the height of the units in that section of the fort to their advantage, funneling the Aud into a waiting hail of sonics and nets.
At this stage in the fighting, the reality had set in. WAVs that were dragged away from the defensive lines didn't resist or try to make it back if they broke free. Their pilots overloaded the batteries, turning themselves into kamikaze bombs as they charged further into enemy territory.
Those that remained wouldn't last much longer, either. The most pristine armor had a non-functioning arm, and most were so badly damaged the legs no longer worked. These WAVs had been propped up against walls or turrets and relied on their armaments alone to make a futile contribution.
Given everything, Pa-5 thought they could hold out for another few minutes, enough time for her to gain another kilometer of breathing room. Her hopes were dashed when she caught a glimpse of purple among the Aud.
The majority of the attackers had been white and orange-furred, which was why the fortress' defenders had lasted this long in the first place. The toughest among the oranges wouldn't withstand a single hit from a titan's cannons, but the fort never held a titan in reserve in the first place. Still, the WAVs had done well enough, coordinating their efforts even in a terrible state to trap and systematically eliminate stragglers, all while pushing back the main bulk of the Aud.
But a purple-furred Aud was as far as could be from the lower tiers. Mostly following the organizational theme of a rainbow, an Aud's fur represented their general threat level. The further along it was, the faster they could move, the stronger they were, the heavier they became, the smarter they thought.
The appearance of a purple Aud always represented defeat, and in marched one, gaping maw and all. As it stepped forward, the fighting slowed. The rest of the Aud backed up, squishing themselves onto either side of the lane even if those further behind them were crushed helplessly under the combined weight of their kin.
The line of WAVs reassembled themselves, grasping the lull in action to reset what overloaded systems and refuel what they could. The purple looked up and down the line and took a step forward.
"Overcharge nets, cone targeting!" an officer cried. At his command, the WAVs exploded back into action. The rest of the horde forgotten, a third launched nets, while the rest of the line launched electric cables. When the purple was fully tangled in netting and scutumsteel wires, the suits collectively unleashed the power of their overcharged batteries.
The purple grunted and coughed up a bit of smoke. Nothing else. No sizzling. No charred fur. No convulsions. Just ten seconds hooked up to the raw power of a single suit core could fry the average human brain to putty. But from a line of dozens, the purple had been subjected to a modest shock.
It flexed, stretching out its hind legs. One by one, the nets and cords snapped under the tension. When it was free, it crouched. It took the time to look over each WAV again, then bolted forward, a speeding whir. Five WAVs in its path were torn asunder, some trampled, some tossed over its powerful shoulders. The rest turned around in an attempt to restrain it, turrets swiveling in a desperate bid to lock on, but the rest of the horde had lost the fear of an apex predator that held them in place.
With their backs turned, the last two defensive lines crumbled like a sandcastle. The screams were brief amid the roars, and all the drone could see was a frenzy of fur. She closed her heart off and directed the drone to return to the outskirts. It wouldn't make it inside the garage without being crushed underfoot, even if it went unnoticed.
"And s-so, Io joined its siblings," she recited a line from a children's book, "and nevermore hosted breath."
She marked down the time; the Directory would want as accurate of a report as they could get; nothing was to be forgotten. It wouldn't do to be caught slacking. If. If. If.
The rest of the journey to her destination was uneventful, and, surprisingly, boring. She had clawed her way from death's grasp multiple times in the last hour; her heart was still racing, even if logic placated her with knowledge that she should be safe for a half an hour minimum.
But that adrenaline couldn't last without a tangible threat to latch on to. So her thoughts sluggishly organized themselves. And she realized boredom was creeping in.
She wanted to laugh. Boredom. Here she was, on her way to inform the last people in the world that the end was nigh, and she felt bored. It was disrespectful, completely and utterly, to every person who died at the fort. But not even shame could rein it in.
She received a message from her HUD: "Accomplishment: Arrival at quaternary checkpoint in three minutes. Quaternary checkpoint: Greater Western Tunnel Systems."