But Simon was still weak, and he got weaker. It was hard not to see this as some kind of moral failing; Nirgal had never been sick, and he found the concept disgusting. It could only happen to the old ones. And even they were supposed to have been saved by their aging treatment, which everyone got when they were old, and so never died. Only plants and animals died. But people were animals. But they had invented the treatment. At night, worrying about these discrepancies, Nirgal read his lectern’s whole entry on leukemia, even though it was as long as a book. Cancer of the blood. White cells proliferated out of the bone marrow and flooded the system, attacking healthy systems. They were giving Simon chemicals and irradiation and pseudoviruses to kill the white blood cells, and trying to replace the sick marrow in him with new marrow from Nirgal. They had also given him the aging treatment three times now. Nirgal read about this too. It was a matter of genomic mismatch scanning, which found broken chromosomes and repaired them so that cell division error did not occur. But it was hard to penetrate bone with the array of introduced auto repair cells, and apparently in Simon’s case little pockets of cancerous marrow had remained behind every time. Children had a better chance of recovery than adults, as the leukemia entry made clear. But with the aging treatments and the marrow transfusions he was sure to get well. It was just a matter of time and of giving. The treatments cured everything in the end.

“We need a bioreactor,” Ursula said to Vlad. They were working on converting one of the ectogene tanks into one, packing it with spongy animal collagen and inoculating it with cells from Nirgal’s marrow, hoping to generate an array of lymphocytes, macrophages, and granulocytes. But they didn’t have the circulatory system working right, or perhaps it was the matrix, they weren’t sure. Nirgal remained their living bioreactor.

Sax was teaching them soil chemistry during the mornings when he was teacher, and he even took them out of the schoolroom occasionally to work in the soil labs, introducing biomass to the sand and then wheelbarrowing it to the greenhouses or the beach. It was fun work, but it tended to pass through Nirgal as if he were asleep. He would catch sight of Simon outside, stubbornly taking a walk, and he would forget whatever they were doing.

Despite the treatments Simon’s steps were slow and stiff. He walked bowlegged, in fact, his legs swinging forward with very little bend to them. Once Nirgal caught up to him and stood beside him on the last dune before the beach. Sandpipers were charging up and down the wet strand, chased by white tapestries of foaming water. Simon pointed at the herd of black sheep, cropping grass between dunes. His arm rose like a bamboo crossbar. The sheep’s frosted breath poured onto the grass.

Simon said something that Nirgal didn’t catch; his lips were stiff now, and some words he was finding hard to pronounce. Perhaps it was this that was making him quieter than ever. Now he tried again, and then again, but no matter how hard he tried, Nirgal couldn’t guess what he was saying. Finally Simon gave up trying and shrugged, and they were left looking at each other, mute and helpless.

When Nirgal played with the other kids, they both took him in and kept their distance, so that he moved in a kind of circle. Sax admonished him mildly for his absentmindedness in class. “Concentrate on the moment,” he would say, forcing Nirgal to recite the loops of the nitrogen cycle, or to shove his hands deep into the wet black soil they were working on, instructing him to knead it, to break up the long strings of diatom blooms, and the fungi and lichen and algae and all the invisible microbacteria they had grown, to distribute them through the rusty clods of grit. “Get it distributed as regularly as possible. Pay attention, that’s it. Nothing but this. Thisness is a very important quality. Look at the structures on the microscope screen. That clear one like a rice grain is a chemolith-otroph, Thiobacillus denitrificans. And there’s a chunk of sulphides. Now what will result when the former eats the latter?”

“It oxidizes the sulphur.”

“And?”

“And denitrifies.”

“Which is?”

“Nitrates into nitrogen. From the ground into the air.”

“Very good. A very useful microbe, that.”

So Sax forced him to pay attention to the moment, but the price was high. He found himself exhausted at midday when school was over, it was hard to do things in the afternoon. Then they asked him to give more marrow for Simon, who lay in the hospital mute and embarrassed, his eyes apologizing to Nirgal, who steeled himself to smile, to put his fingers around Simon’s bamboo forearm. “It’s all right,” he said cheerily, and lay down. Although surely Simon was doing something wrong, was weak or lazy or somehow wanted to be sick. There was no other way to explain it. They stuck the needle in Nirgal’s arm and it went numb. Stuck the IV needle in the back of his hand and after a while it too went numb. He lay back, part of the fabric of the hospital, trying to go as numb as he could. Part of him could feel the big marrow needle, pushing against his upper arm bone. No pain, no feeling in his flesh at all, just a pressure on the bone. Then it let up, and he knew the needle had penetrated to the soft inside of his bone.

This time the process did not help at all. Simon was useless, he stayed in the hospital continually. Nirgal visited him there from time to time, and they played a weather game on Simon’s screen, tapping buttons for dice rolls, and exclaiming when the roll of one or twelve cast them abruptly onto another quadrant of Mars, one with a whole new climate. Simon’s laugh, never more than a chuckle, had diminished now to just a little smile.

Nirgal’s arm hurt, and he slept poorly, tossing through the nights and waking hot and sweaty, and frightened for no reason.

Then one night Hiroko woke him from the depths of slumber, and led him down the winding staircase and over to the hospital. He leaned groggily against her, unable to wake fully. She was as impassive as ever, but had her arm around his shoulders, holding him with surprising strength. When they passed Ann sitting in the hospital’s outer room something in the slope of Ann’s shoulders caused Nirgal to wonder why Hiroko was here in the village at night, and he struggled to wake fv.lly, touched by dread.

The hospital’s bedroom was overlit, sharp-edged, pulsing as if glories were trying to burst out of everything. Simon lay with his head on a white pillow. His skin was pale and waxy. He looked a thousand years old.

He turned his head and saw Nirgal. His dark eyes searched Nirgal’s face with a hungry look, as if he were trying to find a way into Nirgal — a way to jump across into him. Nirgal shivered and held the dark intense gaze, thinking, Okay, come into me. Do it if you want. Do it.

But there was no way across. They both saw that. They both relaxed. A little smile passed over Simon’s face, and he reached over with an effort and held Nirgal’s hand. Now his eyes darted back and forth, searching Nirgal’s face with a completely different expression, as if he were trying to find words that would help Nirgal in the years to come, that would pass across whatever it was that Simon had learned.

But that too was impossible. Again they both saw it. Simon would have to give Nirgal to his fate, whatever it was. There was no way to help. “Be good,” he whispered finally, and Hiroko led Nirgal out of the room. She took him through the dark back up to his room, and he fell into a deep sleep. Simon died sometime during the night.

It was the first funeral in Zygote, and the first for all the children. But the adults knew what to do. They met in one of the greenhouses, among the workbenches, and they sat in a circle around the long box holding Simon’s body. They passed around a flask of rice liquor, and everyone filled their neighbor’s cup. They drank the fiery stuff down, and the old ones walked around the box holding hands, and then they sat in a knot around Ann and Peter. . Maya and Nadia sat by Ann with their arms around her shoulders. Ann appeared stunned, Peter disconsolate. Jurgen and Maya told stories about Simon’s legendary taciturnity. “One time,” Maya said, “we were in a rover and an oxygen canister blew out and knocked a hole in the cabin roof, and we were all running around screaming and Simon had been outside and he picked up a rock just the right size and jumped up and dropped it in the hole, and plugged it. And afterward we were all talking like crazy people, and working to make a real plug, and suddenly we realized Simon still hadn’t said anything, and we all stopped working and looked at him, and he said, That was close.’ “