No wonder Lucius had suspected he might be human. For a time, Derec had wondered if he was a robot. In some cases it was a slippery distinction.

I, too, lack a past,Lucius sent.

Learn to like it,Derec replied.

Avery was waiting for them when they arrived. Derec wondered how he had managed that, then realized that it was his own doing. He had sent him off at high speed. Even the long way can be a shortcut if you go fast enough.

“Very funny,” Avery said as Derec stepped from his booth.

Derec grinned. “You needed to loosen up.”

“I’ll remember that.” Avery turned and stalked into the apartment building, determined, Derec was sure, to do nothing of the sort.

Derec waited for the others to climb out of their booths, then followed after Avery. The apartment was on the top floor of what was currently a twenty-floor tower, but the height was subject to change without notice. Derec had considered ordering the City to leave the building alone, but in the end had decided against it. Variety was the spice of life, after all. Why should he care how tall the building was? On days when it was too tall for stairs, he could always use the elevator.

Avery had already done so, but the car was already descending again. When it arrived, Derec and everyone else packed into it, and Derec commanded it to take them to the top.

The apartment filled the entire floor. The elevator opened into a skylit atrium filled with plants, surrounding a fountain that Derec had copied from an ancient design. From either side of the pool a solid stream of water arched upward in a parabola, the two streams carefully balanced to meet in the middle and spray outward in a vertical sheet of water. Derec was about to lead on past it, but Lucius paused when he saw it, then reached out and interrupted the path of one stream of water with a hand. The last of the stream continued upward as if nothing had happened, but when the gap reached the center, the other beam arched over to splash against the top of Lucius’s hand, just opposite the other water beam. It was obvious that the two beams followed exactly the same trajectory, and could meet anywhere along their paths.

Lucius removed his hand and the two streams met headon again, the point of contact slowly climbing back up to the center.

“Interesting,” he said.

“I call it ‘Negative Feedback,’ “ Derec replied. Unable to resist a little dig, he added, “It’s a useful principle. Think about it.”

If Lucius understood his implication, he gave no sign of it. “I will,” he promised.

Ariel walked on past them, through a massive simulated-wood double door and into the apartment itself. It was a palace. The living room took up one whole quarter of the floor, its glass walls on two sides affording a view of half the city stretching out to the horizon. From the main entryway, a wide, curving hallway led off into the rest of the apartment, one glass wall facing the atrium and the other studded with doors leading into the library, computer room, bedrooms, video room, dining room, kitchen, game room, fitness room, swimming pool, and on into unused space that remained unused only because no one could think of anything else they wanted to fill it with.

The apartment was big and ostentatious, far more than three humans and an alien needed, but as the only inhabitants of an entire city full of robots they had decided to enjoy it. In this particular instance, there seemed little advantage in moderation.

Another robot waited for them in the apartment: Mandelbrot, Ariel and Derec’s personal robot. Mandelbrot was a standard Auroran model, made of levers and gears and servo motors, save where damage to his right arm had been repaired with an arm salvaged from a Robot City robot. That arm could have been any shape Mandelbrot-or his masters-wished, but he had chosen to make it match his other arm as closely as possible.

“You beat us home,” Derec said when he saw him. Mandelbrot had been in the Compass Tower, helping direct the city’s reconstruction from there.

“I left as soon as my task was finished, reasoning that you would come here soon after,” the robot replied.

“Right, as usual,” Derec said, patting Mandelbrot’s metal shoulder in easy camaraderie. He nodded toward Lucius. “Here’s our troublesome renegade, ordered to behave and given a new name to remind him of it. Mandelbrot, meet Lucius.”

“Hello, Lucius,” Mandelbrot said.

“I am more properly called ‘Lucius II,’ “ Lucius said, “to distinguish me from the artist; however, Derec has pointed out that among those who realize the original Lucius is no longer operative, there is little danger of confusion in calling me simply ‘Lucius.’”

“That seems reasonable,” Mandelbrot replied.

Ariel had already disappeared into the apartment, as had Dr. Avery, but from the soft, synthesized music coming from the living room, Derec knew where at least one of them had gone. He waved the robots into the living room as well, then went into the small kitchen just next door. It held a small automat that provided light snacks and drinks for anyone who didn’t want to walk or send a robot all the way to the main kitchen. Derec dialed a number from memory, and the machine delivered up a glass of dark brown, bubbling synthetic cola, one of his own experimental creations.

“Betelgeuse, anyone?” he asked loudly.

“Yecch”‘ Ariel said from the living room.

Wolruf padded into the kitchen. “I’ll ‘ave one,” she said, holding out her hand. Derec gave her the one he had already dialed for, then ordered another for himself and a glass of Ariel’s favorite, Auroran Ambrosia, for her.

From the library Avery said, “Mandelbrot, get me a mug of coffee.”

The robot entered the kitchen behind Wolruf, waited patiently for Derec to finish with the automat, then pushed buttons in the sequence for coffee. Derec shook his head in exasperation. Avery had a whole city full of robots at his command, but he still loved to order Mandelbrot around. No doubt it was because Mandelbrot was Derec’s robot, and Ariel’s before him. Derec had considered telling Mandelbrot to ignore Avery’s picayune orders, but so far he hadn’t felt like provoking the conflict that Avery so obviously wanted.

Ariel was already sitting in one of the single-person chairs in the living room, her back to the glassed-in comer looking out over the city.Adam and Eve and Lucius were seated on a couch at an angle beside her, looking like a triple reflection of her. Wolruf followed Derec into the room and took another chair opposite the robots, leaving Derec with the choice of a chair beside Wolruf or one across from Ariel. Or

Convert Ariel ’ s chair into a loveseat,he sent to the apartment controller, and the malleable Robot City material began flowing into the new shape. The chair’s right arm receded from Ariel while more material rose up from the floor to fill in the space.

“What the-oh. You could warn a girl.”

“But you’re so pretty when you’re surprised. Your eyes go wide, and you breathe in deep…”

“Beast.”

“Thank you.” Derec handed her the glass of Ambrosia and sat beside her.

He took a long pull at his Betelgeuse. It felt grand to relax. It seemed he’d been going full tilt since he’d first heard of these strange new robots. But now, with Lucius tracked down and ordered to stop his human-creating project, the problems he had caused were over. Completely. One nice thing about robots; once they accepted an order to do something-0r not to do it-they were locked into whatever behavior pattern that entailed.

Which, come to think of it, didn’t necessarily mean no more trouble. No amount of orders could cover every eventuality, not even a blanket order like, “Don’t cause any more trouble.” Not even the Three Laws, built into the very nature of their brains, could keep them from occasionally damaging themselves, or disobeying orders, or even harming a human, however inadvertently. It kept such harm to a minimum, surely, but it didn’t prevent it entirely. Nor would anything Derec could do keep these robots from letting their curious nature draw them into unusual situations. They were like cats; only dead ones stayed out of mischief.