But then the door opened: Dr. Collingwood, with Dr. Kyriakides behind him.

Collingwood cleared his throat. “We’re ready now.”

Maxim Kyriakides watched through a glass dividing wall as a nurse installed John in the bone-white ring of the PET scanner and administered an injection of glucose laced with fluorine-18, a radioactive isotope. The isotope would diffuse through the tissues of his body, breaking down and releasing tiny bursts of radioactivity. The video monitor, over which Collingwood was hovering like a protective parent, would then translate this radiation into a picture of John’s brain. Rather, Maxim thought, of the activity of his brain, not specifically the physical structure; this was the superiority of the PET scanner over a CAT. Maxim had never operated such a device; he was more strictly a creature of the test tube, the laboratory animal, the microscope. Consequently he watched from a respectful distance as the images began to scroll up.

“Interesting,” Collingwood said.

“Butterflies,” Kyriakides said quietly.

“Hm?”

“Or Rorschach tests. Like the ones they gave us as undergraduates. Ink blots. Except these are red and blue.”

In fact they were images of John’s functioning brain, and Maxim was able to recognize the left and right occipitals, the temporal lobes, as the scanner read its sequential slices through the skull. But the vivid colors meant nothing to him.

Res externa and res cogita Matter and the mind. Both those categories had lost some of their firmness since Maxim’s college days. Res externa, the notion of the solid body in physical space, had receded into the conceptual fog of modern particle physics. And res cogita—well, we didn’t really believe in it, did we? Maxim had never been a radical reductionist, like Skinner. But it had never occurred to him to doubt that every mental event had its precise physical parallel in the brain; that a “thought” was simply a neuronal twitch of one kind or another.

Today all that had changed. Neurological science was a wasteland of warring theories; the brain was everything from a quantum-event amplifier to a chaotic equilibrium. Every step toward understanding, the discovery of this or that chemical neurotransmitter, seemed to unfold a Chinese puzzle of increasingly complex questions. Some researchers had even concluded that the effort to understand the brain was necessarily doomed—that consciousness cannot comprehend consciousness any more than a box may contain itself.

“This is really an extraordinary amount of activity,” Collingwood said. “There’s no question that what we have here is not a normal scan. It’s all lit up—it’s a bloody Christmas tree. I mean, look at the occipitals. Ordinarily, the only time you’d find that much activity is in a subject who’s hallucinating.” Collingwood looked over his shoulder. “Does he hallucinate?”

“Occasionally.”

“But not just the occipitals. It’s everything! He must be burning glucose at a tremendous rate.”

Maxim said, “No sign of pathology?”

“Hard to say. We don’t have a baseline, do we? I mean, what’s it supposed to look like? However—” Collingwood squinted at the monitor. “There are these shadowy patches scattered through the frontal cortex. If you insist on a sign of pathology, maybe that. But I wouldn’t stake a diagnosis on it.” He frowned. “What did your animal studies show?”

“In a mature chimp with induced cortical growth, a decline over time. Periodic fever, convulsions, then accelerated deterioration of the induced cerebral tissue.”

“Fatal?”

“Often. The decline was always permanent.”

“I don’t suppose you ran PETs.”

“I didn’t have access to a machine. You know what it’s been like.” Funding had dried up decades ago and the work he had performed in the fifties was still tightly classified. Following the cortical growth into maturity and old age in a primate population had been his own idea—an impulse; it would not only satisfy his curiosity, but would be useful if the publication bans were ever lifted. “We did autopsies,” he told Collingwood. “The symptoms were vaguely Alzheimer’s-like, but there was no specific loss of acetylcholine neurons, no neurofibrillary plaques. Our suspicion was that the new cortical growth was sufficiently distinct—in some way—that it eventually triggered an autoimmune response. Mortality depended on how essential the new growth had become to the organism.”

Collingwood shook his head. “All those years ago, doing synthesis protocols—I never really imagined we would have to face this. Him, I mean—a human being, an enhanced adult human being. Are his symptoms severe?”

“Intermittently.”

“Advanced?”

Maxim shrugged.

“Well,” Collingwood said, “we might be looking at tiny lesions, peppered over the frontal lobes. But there’s so much activity, Max, it’s just difficult to say.” He turned back to the video display. Maxim saw him stand suddenly erect as something caught his attention. “Hold on—wait a minute—”

The attending nurse in the PET room picked up a microphone; her voice was relayed to the speaker grille over Collingwood’s head. “Doctor,” she said, “the patient is convulsing—shall I pull him out?”

Maxim hurried to the window. He could see John lying with his head in the mouth of the PET scanner, as if he were being devoured by the machine. His pale, long limbs were trembling slightly.

Collingwood looked at Maxim; Maxim shook his head.

Collingwood said, “Hold him steady a few more minutes.”

There was silence, punctuated by the whirring of disc drives. Maxim looked over Collingwood’s shoulder at the video display.

The butterfly-wing image of John’s brain was changing, subtly but distinctly. The bright colors began to fade; in particular, the hot band of the frontal lobes faded toward shadow. Watching, Maxim felt a cold hollowness at the pit of his stomach. “What’s happening?”

“His glucose economy is suddenly down. Behaviorally, you mean? Jesus, I don’t know—I’ve never seen anything like it.”

Maxim said, “He’s changing.”

“That’s obvious!”

“I mean, he’s not John anymore. I think he’s becoming Benjamin.”

“The secondary personality you mentioned?”

“I believe so.”

“This is radical,” Collingwood said. “I’ve never seen this kind of bottoming-out. Is this voluntary?”

Maxim began to shake his head, then reconsidered. It was a tremendous coincidence, that Benjamin should manifest just as John was in the PET scanner. It was as if John wanted to show us this, Maxim thought. John’s way of cooperating with the test.

Or Benjamin’s.

“Not exactly voluntary,” he told Collingwood, “not on the conscious level. But John is a unique individual. Not voluntary, but perhaps not an accident.”

“The patient is febrile and convulsive,” the nurse reported, “but he seems to be coming around… Doctor?”

“Pull him out,” Collingwood said.

He switched off the intercom and looked at Maxim. Video images were still cycling through on the monitor behind him. Cool blue butterfly wings. Icy Rorschach blots. “Jesus Christ, Max,” Collingwood said tonelessly. “What did we do to this man? Just what kind of thing is he?”

Benjamin was back. But Benjamin had changed.

Amelie was deeply pleased, at first, to be with him again. She realized how much she had cherished the time before Benjamin went away—before Roch moved in and took his place. Having even a fraction of that life restored was like an answered prayer. She worried that there might be some conflict with Susan or Dr. Kyriakides, but there was not; aside from the time Benjamin spent in therapy sessions with Kyriakides and a few medical tests, Amelie was allowed to have him to herself. Susan maintained a polite, somber distance; and after a few days she left the city on some mission for Dr. Kyriakides.