“It may surprise you for me to say it, but no, I’m not insulted. If I had your skills in robotics, I’d be, well, proud.”

Was it his imagination, Derec wondered, or did his father’s eyes momentarily glaze over? As he looked more closely into the man’s cool and detached eyes, he decided it must have been imagination.

“Well,” Avery finally said, “you’re pretty skilled in that area already. You may surpass me-and don’t say anything more about it now. We should pursue other subjects.”

“We will. Ina moment. I have to know one thing, then I’ll let you off the hook.”

“Just don’t mistake me for an affectionate father.”

“I could hardly do that.”

Avery had walked away from Derec, and his back was turned to him.

“You said we were once close,” Derec said. “Why did that change?”

The answer came out abruptly, bitterly.

“Your mother left me.”

“Tell me about her. “

“No.”

This time his “no” was spoken softly, but with no less firmness. Derec was going to have to work hard to find out anything about her, that was abundantly clear.

“Derec,” Avery said softly, “even talking with you is difficult for me. Don’t expect a plethora of revelations.”

Derec nodded. “All right, I won’t.”

He wondered if he should walk to his father, perhaps embrace him, perhaps ask him if they could start over, perhaps suggest that he would still like to sit on a high stool and watch Avery work.

He took one step toward his father but was interrupted by a noise at the door. Turning around, he saw Wolruf limp into the room. She was clearly on the point of collapsing.

Derec rushed to her and caught her before she fell. Gently he eased her to the floor and felt for her pulse. The slow rate of her pulse beneath her normally cold skin assured Derec that whatever injuries she may have sustained, she was alive and not in immediate danger.

Avery, reaching over his son’s shoulder, delicately spread areas of Wolruf’s fur apart. She winced with pain.

“There seems to be a bruise on her neck,” he said, “a big one.”

“He strruck me there,” Wolruf said in a raspy voice.

“Who?” Derec asked. “Who hit you?”

“The Bogie that iss not Bogie.”

“All right, Wolruf. I want you to tell me about it. But don’t strain your voice. Speak quietly, slowly.”

She explained what had happened when she had caught up with Bogie, and how Mandelbrot and Timestep had continued the chase.

“Okay,” Derec said when she finished, “you rest right here. We’ll get you to the medical facility as soon as we can.”

“No, Derrec. I will be fine ssoon. You have too much that’ss necessary to do now.”

“Well, we’ll see.”

Derec stood up and turned to his father, asking, “What do you make of it?”

“I have some suspicions, but you tell me what you think first.”

Derec felt an odd pride in the way Avery solicited his opinion, almost as if they were colleagues now.

“Well,” he said, “whoever attacked Wolruf, it wasn’t Bogie.”

“I agree, but why?”

“It simply wasn’t a Robot City robot. They are all programmed to accept her as a human. That is, although they know she is an alien, they are to apply the Laws of Robotics to her, too. If Bogie was stopped by her, he would have had to allow it, according to First Law. Instead, he retaliated.”

“Was he reprogrammed perhaps, while you were off-planet?”

“I don’t think so. He was a proper robot previous to this incident, applying all the Laws to his behavior. No, if Bogie attacked Wolruf, he was not Bogie. I sensed a change in him before I sent him on an errand. I rather liked Bogie, and this one simply did not respond like the Bogie I’d known. And, by the way, all indications are that the robot I ordered to go to Ariel never even tried to get there, another clue that I didn’t give the order to Bogie, who would have been compelled by Second Law to obey it. Furthermore, in responding to Wolruf’s leap upon him, he seems to have been using Third Law, that of protecting himself, but First and Second Law would have prevented him from doing so.”

“Okay, good. Then if he wasn’t Bogie, who was he?”

“An alien?”

“What alien? Except for Wolruf, I haven’t encountered any aliens. You have, what with Aranimas and your erstwhile friends, the blackbodies. None of them have any talent for disguise, nor have the few alien races that have been reported. A human might pull off such a disguise, get into a robot suit and do a fairly accurate imitation, but there is no evidence of any other humans but us on the entire planet. If I were still mad, we might have made out a good case for it being me.” He laughed softly, sardonically, then said reflectively, “I did so want to be a robot. I still say the role would have suited me. So, Derec, who do you think it might be?”

“How about a robot, one that’s not programmed in the same manner as a Robot City robot?”

Avery’s eyes raised in admiration. “Very good. You’re right on the line of my thinking. It’s a robot, I’m sure, but not an Avery robot.”

“Why are you so sure?”

“It would have to be some kind of rogue robot. Not my style at all. An Avery robot would not have so much confusion about the three laws. No, somebody else made this robot, and I have a sneaking suspicion who.”

“Who? Tell me.”

Avery shook his head slowly. “Not now. In a moment. I have some questions to ask you. I need to know about Adam and Eve. Your view of them. I know where they came from, what they’ve done so far. Adam gave me a pretty full history during our marathon sessions together. What do you think of them? Robotically speaking, I mean.”

“I’m not sure what you want.”

“Free-associate about them, if you like. “

“Well, I don’t know.” He paused, trying to collect his thoughts. “Sometimes they don’t seem like robots.”

“Uh huh. I’ve noticed.”

“One thing, they can be too mischievous. I know some of it’s curiosity and some of it has to do with their over-meticulous attempts to define some kind of impossible human being, an ideal we apparently fail to live up to. As a result, their hold on the Laws of Robotics is shaky.”

“That seems to be because they apply them too specifically. Rather than accept us as the perfect humans they seek, they strip us of our humanity in their minds, and the result is that they don’t always jump to our aid according to First Law, or obey us as Second commands.”

“That’s not all of it, though. They don’t seem to be certain that they are robots, in spite of all evidence. They accept it and don’t accept it simultaneously. It’s as if their mechanisms are so refined, they can’t be ordinary robots like the others.”

Avery winced. “By ordinary, you mean Avery robots.”

“What’s wrong?”

“I don’t like to think of my creations as somehow second-class models.”

Derec smiled. “If you say so, but I don’t think it’s a criticism of your skills as a roboticist. At any rate, their behavior is inconsistent. Sometimes they seem to be normal robots, at other times they are excellent copies of whomever they’ve imprinted on. Adam does a mean Wolruf, and Eve’s version of Ariel makes me edgy because it’s too accurate.”

“It’s this shape-changing ability that fascinates me, Derec. Explain it to me.”

Under Avery’s sharp questioning, Derec revealed what he had observed about the Silversides, about the differences in their cellular structure, about the sequences of physical transformation during the imprinting process, about the shifts in matter density when they took on the shapes of either smaller or larger beings, about the limits to which they could reduce or enlarge their mass. (Neither could approximate the size of small animals or insects, but could look like enormous versions of them. By the same token, if giants had been available, they could not stretch themselves to that size, either. When they had shaped their mass into a blackbody imprint, they had been about twice the size of that impressive flying alien.)