Carlotta was doing gravity calibrations in the field footing at the very back of the ship when Ender came in to life support, which was just above where she was working. Or just forward of it, depending on how you thought of the ship.

"Sergeant needs a dog," said Carlotta.

Ender jumped. "What are you doing down here?"

"My work," said Carlotta. "What are you doing?"

"Samples," said Ender. "We've been working with viruses for gene splices for a long time, but there's some productive work being done with bacterial latency and chemical triggers."

He sounded so happy.

"I was hoping you could help me come up with something that will help Sergeant bear his life. He suffers more from loneliness than you and I do. He's more like Father."

"The Giant and Sergeant? I never thought of that, but I think you might be right. Sergeant needs to be a street kid in constant danger of starving or getting killed. That would occupy him nicely. So what you really want is not a dog for Sergeant. More like a sabertooth tiger. Something that is stalking him constantly so that he can devote himself to fighting off genuine threats so he doesn't have to keep making them up."

"I was thinking more along the lines of a companion that extends his life beyond the boundaries of the ship."

"A dog on another world?" asked Ender. "There are bio-research labs on several worlds that are studying various xenofauna. I assume you're suggesting that I invent some kind of excuse for this to be a project of mine, which I would talk about with believable enthusiasm, so that Sergeant will think he's sneaking behind my back to get control of the creature and divert it to his own purposes."

"Something like that," said Carlotta.

Ender said nothing more. He closed the lid on his last sample and left life support.

Carlotta was already finished with her readings. As usual, everything was working fine.

What routine, boring, lonely job was next? She hadn't checked the tracking software for a while. Weeks? Days? At least days. She closed up the floor panel over the gravitational field sensors and made her way to the elevator shaft.

When she first stepped onto the platform, it was a small floor under her feet. But as it moved upward, it passed into a flux zone, where she felt herself falling in every direction. She was used to it, though it still gave her a bit of an adrenaline rush as her body felt the usual momentary panic. The limbic nodedeep in her brain didn't understand that she no longer lived in a tree, no longer had to panic when she felt herself to be falling.

Ender was in the lower lab when she got there. It took her a couple of steps to move fully into the zone of Earth-normal gravity that the ship maintained in the forward compartments, where Father couldn't go anyway. Ender didn't look up -- he was busy inserting his samples into various bits of equipment, some of them for freezing, some to be worked with right away. He had no time for her.

Wordlessly she passed Ender and climbed up into the upper lab. She sat down at the terminal for the tracking computer, brought up the holocharts, and began going through all the star systems that fell anywhere near their future path, starting with the stars they were just about to pass and working forward. The computer was looking for the arrangement of mass in each system in order to estimate how the gravitator would have to adjust its lensing.

It was on the fortieth star she looked at -- one that was still several months in their future, but would come fairly near to them -- that the computer pointed out an anomaly. There was an object that was being tracked as belonging to that star system, but according to the computer report, the object's mass kept changing.

That was impossible, of course, a mere artifact of the data. The mass didn't change, that's simply how it was reported. What was actually happening was that the object was not moving on a path that was predictable in relation with the known masses of the star and its larger planets. So the software kept adjusting the estimate of the object's mass to make it conform to its most recent movements.

It wasn't an "object" at all. It was using its own power to move on a path it chose itself, independent of the gravity of the star and its planets.

Carlotta told the software to regard the object as a starship.

Immediately she got a very different report of its past movements. The ship now had a constant mass -- more than a thousand times more massive than the Herodotus. But the trajectory now made perfect sense. The ship was slowing down as it entered the star system. It was heading, not toward the star, but toward a rocky planet in the goldilocks zone.

But Carlotta didn't care much about the planet. Planets were of no use to them because Father couldn't stand even half a gee, let alone 1.2. The fact that the alien ship was approaching it suggested that the atmosphere was attractive to whatever species the ship belonged to. But what mattered to Herodotus was the existence of the alien ship.

The human race had encountered only one alien species, ever, and had fought a war of extinction with them. According to a story told by the writer of The Hive Queen under the pseudonym "Speaker for the Dead," the Formics had not meant to wipe out the human race at all. But Carlotta wasn't buying it -- it was easy to impute benign motives to an alien species that no longer existed.

The trouble was, it was too late to avoid meeting the species. No matter what the Herodotus did, it would be detected -- and its plasma path could be followed back till it disappeared. And since their flight had been straight as an arrow since they reached near-lightspeed, all the aliens would have to do to find the human home world was keep on going straight along the path marked by the Herodotus's plasma emission trail even after the trail itself petered out.

It would be far more useful to slow down and stop, not turn, so that they could discover as much as possible about this alien ship and its inhabitants. Using the ansible, they could report every speck of information they found -- right up to the moment when the aliens destroyed them. The human race would then have time to make whatever preparations might be possible to meet these aliens when they followed the Herodotus's trail back to Earth.

And it would give Sergeant something useful to occupy his time instead of plotting ways to kill Father -- or whoever his enemy might be today.

Carlotta sent a signal to Ender and Sergeant. Come with me to talk to the Giant. Something important has come up. Then she copied the pertinent charts and reports to Father's holotop.