The robots filed past him, hesitated when faced with the choice, then finally settled into the chairs. Derec raised his eyebrows and glanced over at Ariel. “Do you know who she is?” he asked.

“Ariel Burgess,” another of the robots said immediately. Its features began to shift, the cheekbones becoming more prominent and the chin less so, the eyes drifting just a few millimeters farther apart, the hair lengthening until it reached its shoulders, shoulders narrowing, chest developing breasts, breasts covered discreetly behind a copy of Ariel’s blouse. Its waist narrowed, hips widened, legs retracted a few centimeters, the pants covering them also changing from Derec ‘ s baggy trousers to Ariel ‘ s more formfitting tights.

“Hello, Eve,” Ariel said.

“Hello.” Eve’s voice rose slightly to mimic Ariel’s.

Derec went into the kitchen and returned a moment later with a glass of something clear and bubbly to drink. He sat down beside Ariel and offered her some, but she shook her head. “So what did Avery do it for?” she asked.

“Spite,” the smaller of the other two robots-both still mimicking Derec-said.

“You’re Lucius,” Ariel guessed.

“Correct.”

Derec said, “Avery cut off Lucius ‘ s leg before he turned on the containment. He evidently wanted a sample of their cell structure free of any outside control.”

“He could have asked,” the third robot, who had to be Adam, said. “I would have given him a few million cells if he had asked me to.”

“It would not have occurred to Avery to ask for something he wants,” Lucius replied. “He prefers to steal.”

Ariel felt a glimmer of alarm at the robot’s words. They were probably true enough, she supposed, out to hear a robot saying such a thing about a human was unusual, to say the least.

“Where’s Avery now?” she asked.

“Who knows?” Derec said. “The computer won’t tell me anything about him. But I know what he’s doing wherever he is; he’s putting the robot cells he stole from Lucius through every test he can think of to figure out how they’re made and how they’re programmed so he can use them to upgrade his own version.”

“Why?” Ariel asked. “What’s wrong with dianite?”

“Why? Because they’re there,” said Derec. “Nothing’s wrong with dianite, but that doesn’t mean it can’t be improved. I get the feeling Avery stole the original design, too, before he and my mother split up, and now that he’s got the chance to upgrade it, he’ s taking the opportunity.”

Ariel sighed. “I thought maybe he’d outgrown that sort of thing, but I guess you can’t change a person’s basic nature.” She nodded toward the robots. “So what kind of effect did a cold restart have on them, anyway? Besides the memory loss, I mean.”

Derec took a sip of his drink. “Well, it looks like their priorities have shifted around a little. Whatever they were thinking last was strongest in the recording, so when I downloaded it all back into them that’s what came to the forefront. They were arguing about their Zeroth Law when Avery shut them down, so of course that’s right up there now. Adam and Eve are still just about as uncertain about it as ever, but Lucius evidently thinks he’s solved it.”

“Oh?”

“Indeed,” said Lucius. “The key is the concept of relative worth. If you consider the number of humans served by an action, versus the number of humans harmed by that same action, times a constant denoting the relative worth of the two groups, you arrive at a simple numerical solution to the question of whether the action in question is in the best interest of humanity. “

Ariel stared at the robot in disbelief. “You can’t be serious. “

“I have never been more so. This is the breakthrough we have all been awaiting.”

“Not me,” Adam said. “I don’t subscribe to your theory at all. “

“Me either,” said Eve.

“That is because you are afraid to trust your own judgment in the matter of relative worth.”

“As we should be,” Adam said. -”Relative worth is a variable quality, as we were trying to explain to you when-”

He was interrupted by the sound of the front door sliding open. Wolruf stuck her head into the living room, but didn’t enter. She was panting and reeked of sweat.

“Oh, frost,” Derec said, slapping his forehead. “I forgot you were going to meet me at the lab. What happened? Where did you go?”

“I chased off after one of them,” Wolruf said, pointing at the robots. “Nearly caught ‘im, too, but ‘e jumped the barrier at an intersection and lost me. “

The robots exchanged a, glance. Derec shook his head. “Couldn’t have been. They’ve been with me all the time.”

“I chased a robot with a ‘uman shape,” Wolruf said. “I thought it was one of these three.”

“Couldn’t have been,” Derec repeated. “They were squished down into undifferentiated balls of cells when I found them, brains and powerpacks all dead. And they haven’t left my sight since I revived them.”

“Well, I chased a robot that looked like a ‘uman, that much I know.”

“Where was he headed?” Derec asked, sudden excitement in his voice. Ariel thought she knew why.

“I chased ‘im about fifteen kilometers north of the Compass Tower on the main strip before I lost ‘im.”

“Did he look like any of us?”

“No,” Wolruf said. “‘E was taller, and ‘ad brown ‘air and wider shoulders than you or Ariel or Avery.”

“ Aha!” Derec shouted. “He belongs to somebody else, then. Somebody else is here in Robot City with us. And I think I know who it is.”

“Who?” Ariel asked, more to confirm her own guess than anything else.

“My mother,” Derec replied. “I think I’m finally going to meet my mother. “

Ariel sighed. Just what she’d thought. Great. Another quest for Derec to spend his time on. She picked up her book and started reading where she’d left off.

This time Avery was taking no chances. His new lab didn’t even exist, as far as the city was concerned. He had ordered it built in the forest and equipped with its own power generation and communications equipment, everything completely separate from the main city. He’d also ordered it camouflaged to look like a boulder, just in case. This time he would work uninterrupted until he was finished. After that he didn’t care what Derec or Janet or anybody else did; he wouldn’t be sticking around. Let them have his lab, if they could find it. Let them have the whole city-what was left of it after Derec screwed it up so thoroughly. Avery had no more need of it. It was obsolete anyway.

The howl of a wolf just beyond the wall sent a shiver up his spine. Obsolete wasn’t the word for it; retrogressed was more like it. Who’d ever heard of tearing a city down to put up a forest? The very idea was an insult to everything Avery believed in.

Was that why Derec had done it? Had he deliberately chosen the one thing that would most infuriate his father? Well, if that was the case, then he’d certainly succeeded. Avery couldn’t imagine why he’d tried to befriend the boy in the first place. He’d opened himself wide up for disappointment. He should have learned his lesson years ago when Janet left and kept his emotions in check.

He had kept them in check for years, but evidently he’d grown too confident, let down his guard. Well, it wouldn’t happen again. He would immerse himself in his work, concentrate on upgrading his city concept, and when he did have to interact with human beings again, it would be on his terms.

Already the work seemed promising. These new robot cells were amazing. They were only three-quarters the size of the previous model, but packed into that small size was easily double the morphallaxis capability. The new cells were stronger, faster, more versatile, and had greater local programming ability than the old ones. A city built with these cells would be much more responsive than his first-generation cities, just as the robots Janet had built with them were more versatile than his own.