"I won't bore you with the details of four centuries of fighting. They never have caught up with us in physics, and we never have caught up with them in the organic sciences. They're a bit ahead of us in chemistry, too, but we've got a huge edge in weapons, computer science, FTL technology-all the hardware aspects of fighting a war in space-and we're better strategists. Their caution works against them, and we're a lot more tuitive. They can kill any planet they can range on, but so can we, and our advantages mean that they've been pushed onto the defensive. They have to get past the fleet to attack our planets, and we've shoved them further and further back with every generation. By now, they're penned up in just three star systems, and we've got them pretty much blockaded there."

She paused again, and he cocked his head to one side.

"Excuse me," he said, "but I don't quite understand. If you're so much better fighters, how have they lasted this long?"

"They aren't stupid, Ster Aston," she said grimly, "just xenophobic and fanatical. Somewhere fairly early in the fighting, they decided that some fundamental difference in the way our minds work gave us an inherent advantage. It must have galled them, but the fact was that we were better fighters, and they were losing. Not all the time, and not all the battles, but most of the big ones. So they decided to do something about it."

"But what could they do?"

"They used their own strengths. If we had some kind of inbred advantage, they had to acquire the same advantage for themselves. So they built a race of cyborgs."

"Cyborgs?"

"Cyborgs. Machines with organic brains."

"But if the problem was inbred-"

"I didn't say machines with Kanga brains, Ster Aston," she said harshly. "They had prisoners of their own, and they're fantastic biological engineers. They developed a method to build total obedience into an organic brain. Then they operated on their prisoners."

Aston stared at her, stomach heaving as the implications sank in.

"Yes, Ster Aston," she said coldly. "They decided, in your idiom, to set a thief to catch a thief. If humans could out-think and out-fight them, they needed humans of their own. Their cyborgs were never quite as good as having regular humans, and they've never trusted them entirely. Strategy and sensitive research are still in strictly Kanga hands, but tactics and actual combat are another matter. Their cyborgs are completely expendable, and obedience is engineered into them; they can't even argue about being expended, but they're very good at what they do. By now, the Kangas are actually 'farming' to produce them." She looked ill, but her voice was level. "They clone human brains to produce the things that do their fighting against other humans."

"My God," he whispered, holding his cold pipe.

"God had very little to do with it," she said softly, "and the hell of it is that the cyborgs hate us even more than the Kangas do. We're the ones who keep killing them, but, in a sense, we're also related, and it horrifies and disgusts both of us. They're slaves to the Kangas; even if we wanted to, we could never forget that, and they know it. We didn't create them, and we're not the ones who enslaved them, but they know exactly how horrible we find them, and they feel-and share-our hate.

"When we first realized what they were, we tried to overcome our disgust," she said even more softly. "We really tried, but it didn't work. They're fighting machines-by our standards, their human brains are psychopathic, because the Kangas wanted totally obedient, highly skilled, utterly conscienceless killing machines. They got them, too. The first time we cornered some of them and tried to talk to them, they slaughtered our entire contact team-over a hundred people-even though they knew we had enough troops and firepower to exterminate them.

"In two hundred years, every single confrontation with them has ended in death-ours or theirs. They're poor, bastardized monsters, but they are monsters. We can never let ourselves forget that. I think that's why we never call them 'cyborgs.' "

"What do you call them?" he asked, his voice barely above a whisper.

"We call them Trolls, Ster Aston," she said quietly, "and one of them shot down my interceptor and killed my crew. That's what's loose on your planet-and somehow, we have to find it and kill it."

Ice spicules danced on a howling wind. They'd rattled on the tough alloy, at first; now they only burnished a thick and growing cocoon of ice. The metal skin within exactly matched the temperature of its icy coat, and the interior of the hidden vessel was scarcely warmer. The last surviving Troll sent another surge of current through the heat field that kept his light receptors clear as he watched the gray and white and black-rock bitterness of Antarctica.

This place suited him. It was a fitting place to pause and consider. There was no fear of discovery, for there was no life here, no slightest living thing to disturb his gloating triumph, nor did the chance of distant observation concern him. The technology which had surprised his Shirmaksu masters had surprised him, as well, and he had no more data on this world's current capabilities than they did, for all that his organic ancestors had sprung from it. But what had happened gave him a crude benchmark, and his own sensors had confirmed the presence of several hundred small, obviously artificial objects in orbit about it. It seemed that these humans had primitive spacecraft-of a sort, at any rate-and the sheer numbers of satellites, coupled with the humans' extensive (if crude) weaponry and military readiness, argued that there were probably optical and thermal reconnaissance platforms among them. Not that it mattered now. The astonishing rapidity of their response to what had to have been a totally unexpected threat had surprised him as much as it had his masters, however much it galled him to admit that, but they would not surprise him again, and their satellites would not see him here. They couldn't, for there was no longer anything to see, now that his fighter had merged with the ice and snow, and there was no heat to detect, for he had no need of heat.

The moaning wind pleased him in a way he could not have defined even to another of his own kind. It was like a kindred soul-powerful and pitiless. Its icy breath didn't bother him. Indeed, cold and heat were merely abstract concepts to him, as meaningless as weariness and as alien as pity. Pain he understood, for that was how the Shirmaksu "programmed" his kind. Direct stimulation of the pain and pleasure centers communicated displeasure and grudging approval quite well, he thought coldly, savoring his hate anew.

Yet what he felt now was a special sort of pleasure. It hadn't been inflicted upon him; he had won it for himself. It was ... personal.

He watched the wind of the driving blizzard and quivered with a sort of cerebral ecstasy. He was free. Obedience to the Shirmaksu had been engineered into him, reinforced by agonizing training and long habituation, yet there were no Shirmaksu now for him to obey. The cralkhi's missile had done that for him, had snapped the intangible and thus unbreakable chains which had bound him for so long.

The Troll hadn't recognized that immediately. He'd pursued the cralkhi to its death, obedient to his masters' final orders, before he realized there were no more masters. Not that he would have spared the cralkhi even if he had considered the gift it had given him. The cralkhi had been his enemy, its interceptor the only force which might have challenged him, its brain the only source of information which might endanger him. Logic had decreed that the cralkhi must die, but he hadn't needed logic. Hatred was sufficient.