C4T never slept. Its skin absorbed the light of day at 80% conversion efficiency, and stored it for the night at 95% roundtrip efficiency. It was lazy in the day by design, but incredibly efficient at night.

It was perched up on the roof of the bookstore, watching the procession of Alphas below. The rest of the squad had also decided to forgo sleep, keeping ready to face any sort of attack. Just one Alpha needed to get a whiff of them, and the rest of them would come barrelling down.

It was doubtful that they could get through the door, though. A net of carbon monofilaments anchored the door to the wall. The wall was better off being destroyed first, but it would take a Beta to do that.

That was why C4T was being a cat-loaf on the roof, looking for the damned things, its paws on the metaphorical red button. The moment a Beta appeared, their defense condition would be promoted all the way up, and Assassin micro-drones would home in on the Beta, delivering a decapitating strike to the danger.

It would rile up the surrounding Alphas, but they were just fodder. Coronel would rather gun down every single Alpha in the block than make a hasty roof-wards retreat and leave their freshly-processed resources behind.

Saito and Eliso were huddled behind the bookstore counter. Coronel was busy nanostructing defensive spikes and razoredge monolines from filament nanites. If the Alphas came barging in, they’d be impaled on thousands of meter-long carbon needles and cut to pieces by nanotube strings criss-crossing the room. The stuff didn’t use up any precious manites, either, so it was a cost-effective option for them.

The things easily caught on fire, though, so they’d have to watch their aim. They weren’t particularly durable, either, but that was fine if only just for tonight.

“They’re just wandering out there,” Saito said. They had short-range cameras affixed to the walls outside and opposite the street, besides sharing C4T’s own visuals. “Why didn’t they come out in the day? We couldn’t find them, too.”

“They prefer darkness,” Coronel replied. “Don’t get any ideas and make a ruckus in broad daylight, either. Make yourself an easy target, and the time of day won’t matter.”

“They can tell?” Eliso asked.

“They’re made to be predators.” Coronel aimed at the door. “Hyper-optimized to hunt down every last human on the face of a planet.”

“Why’d the Kartesh even need to go through so many loops? They could’ve just RKV’ed the place and be done with it.”

Coronel glared at him. Eliso gulped. He might’ve plucked a string he shouldn’t have.

“We’re a resource in their eyes. Don’t forget that,” Coronel said.

A grenade-sized detonation threw everyone’s focus into gear. Only Coronel didn’t flinch. He’d seen C4T’s visuals, noticing an odd one moving among the crowd outside.

The Alpha’s reacted as expected. Without knowing the direction, they started attacking any door and window within reach, ransacking the whole street—and even the bookstore, too.

They couldn’t get in, though. Their hands couldn’t claw through iron bars, and though their hands ripped out bits of the door, they finally hit the reinforced layer.

“They’re stronger than I thought,” Saito said.

“At least they aren’t stronger than nanotubes,” Eliso replied.

They weren’t. Eventually, the wooden part of the door was gone, and a single layer of carbon textile was all that kept the Alphas out. It was like tissue paper at this point—tissue paper with ridiculously high tensile strength. The stresses of the continued intrusion were all within spec, though, and they never got through.

A second blast happened around midnight, attracting more Alphas to the area, roused to rowdiness once more. Other than that, the night passed without a single laser crack.

***

The sun was up, and they were, too. The packbots were loaded with the nanite capsules and whatever extra Assassin micro-drones they’d managed to make. Two had been used up last night, but that was well within Coronel’s expectation.

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They had two types at the moment. One, the Assassin-E, was a flying shaped charge for when they wanted to absolutely murder something specific that just happened to be too sturdy for conventional options. The other, the Assassin-K, was a flying grasscutter with carbon monofilaments spinning around and slicing at tendons and necks. It wouldn’t make for a straight decapitation, but Kartesian bioweapons could die from blood loss all the same.

The theory was the Assassin-K’s would be zipping around and taking care of the trash while the Assassin-E’s shot molten steel along the longest internal distance of the target.

The Assassin-E’s had their test run last night. The Assassin-K’s were up next.

The street outside was still filled with Alphas, more than the initial wandering mob last night, drawn here by explosions throughout the night. From each end of the street, it was just heads and bodies. There wasn’t even space for a cat down there.

C4T agreed to help put a freshly-nanostructed photovoltaic blanket on the roof. The cat was plenty strong, plenty sneaky, and it looked like the Alphas tended to ignore non-human things more easily. It climbed up the ladder from the narrow balcony, which had space for little more than a few potted plants.

It may have kicked over a pot and killed something down there. It didn’t matter.

The photovoltaic blanket was thin enough that it could be rolled up into something like a roll of tissue paper. C4T got to work unrolling it one way, then unfolding the resulting rectangle bit by bit, until there was a 10-by-10 meter photovoltaic plant on the roof.

Eliso and Saito were standing by the narrow second floor windows, their laser rifles plugged in and drawing power from the photovoltaic blanket. As long as the sun was shining, they didn’t need to think about the meager 10-shot capacity of their rifles’ batteries.

Coronel appeared on the balcony. He tossed out a bundle of five Assassin-K’s like he was tossing out a handful of rice.

The straw-shaped Assassins' floppy propellers flapped out and started spinning with a high pitch, pulling up the rest of their bodies. Their course abruptly went from straight down to straight up, but then stopped to hovering a meter above the heads of the Alphas.

Then they got to work.

They whizzed by the necks of the Alphas, spinning up a secondary motor that whipped around a single carbon monofilament, just a few inches long. A single, deep slice across an important artery was all it took. The Alphas complained in gurgling growls, clawing at the blurs and the noise, only to end up clawing off the faces of the Alphas beside them, who responded the same in anger—but to be so angry, and so powerful, all the time, the Alphas had been designed to cast away the typical constraints that kept an ordinary human from self-destructing, and so they would rip their muscles to shreds if it meant the strength to rip open a door to get to a survivor.

Most importantly, they had such a high blood pressure, that blood spurts always had a theatrical effect. Lopped-off limbs experienced a little bit of reactive thrust, often causing them to rotate slightly in mid-air. Decapped heads popped off like they had a wound-up spring for a neck. It was all very … well, at least there was a lot of visual confirmation.

After ten seconds, the slashed Alphas started experiencing dizziness. After twenty seconds, they’d basically squeezed out all their blood like a desolate toothpaste tube. Just like that, they were dead.

Coronel tossed out another bundle, and another, until there were twenty Assassin-K’s zipping around, independently targeting and lacerating arteries for a swarm effectiveness of dozens of Alphas taken out of action per second.

Coronel picked up his laser rifle as Saito and Eliso opened fire, joining them soon after. Their kill contribution was abyssmal compared to the Assassin-K’s, their survival rifles only able to fire one shot per second, but there was one little performance issue with the Assassin-K’s they couldn’t ignore: battery life.

The Assassin-K’s floated up and into the balcony, Coronel staying well the fuck away. It’s not as if they would’ve killed him, even by accident, but being lacerated by monofilaments was a different kind of pain compared to being stabbed. He would much prefer being stabbed, and he had the experience to be able to say that with certainty.

The Assassin-K’s docked on ersatz charging stations. A cable snaking down from the roof supplied the power.

“Sir, they’re riled up!” Saito announced as he continued firing.

“What are they doing?” Coronel asked.

The answer was an Alpha climbing into the balcony. C4T promptly fell on it from the roof and extricated the head from the body, punting caput et corpus off the edge and letting them fall into the street. C4T rushed backed up to the roof, as Coronel already had his rifle ready for the next one. He promptly vaporized the hand that appeared, then rushed to the edge, pouring fire into the column of Alphas that made the small climbing spire.

The bastards were genetically engineered to know how to make a self-optimizing cheerleader formation to make the tallest climbing ramp with the least number of bodies.

Optimize against laser fire, you fuckers. “Saito, Eliso, focus fire on the climbing spire!”

The spire collapsed, but more Alphas rushed in to rebuild it. It was like watching manites rebuild a whole nanostruct after a failed operation.

Finally, the Assassin-K’s had recharged, and they rushed out past Coronel. He ignored his fear of monofilament laceration in favor of directing the Assassin swarm to keep any more Alphas from joining the climbing spire.

There were too many moving elements. His cerebral aim assist program was locking onto one Alpha then snapping to the next just as it passed by. It was annoying, but it was a guaranteed hit. Invisible laser shots blasted off limbs and opened up heart chambers into open, smoking air.

The battle continued for the next 10 minutes. It was amazing what kill rate a three-man, one-cat team could achieve with a bit of technology.