(We have one absolute leader at a time; when he/she/it dies, another is born. More intelligent, larger, stronger, and faster than the rest of us, and usually long-lived. Unless humans interfere, it turns out.)

The leader, whom Carmen christened Red, took a floater out and picked up Carmen and her idiot robot companion, called a dog, and brought them back to us. Our medicine cured her broken bones and frostbite.

We are not sure why it worked on her, but we don’t know how it works on us, either. It always has.

We agreed not to speak to her, for the time being. We only spoke our native languages, which the human vocal apparatus can’t reproduce. Humans can’t even hear the high-pitched part.

So Red took her back to the colony the next night, taking advantage of a sandstorm to remain hidden. Left her at the air-lock door, with no explanation.

It was very amusing to monitor what happened afterward—we do listen to all communications traffic between Earth and Mars. Nobody wanted to believe her fantastic story, since Martians do not and could not exist, but no one could explain how she had survived so long. They even found evidence of the broken bones we healed but assumed they were old injuries she had forgotten about, or was lying about.

We could have had years of entertainment, following their tortuous logic, but illness forced our hand.

All of us Martians go through a phase, roughly corresponding to the transition between infancy and childhood, when for a short period our bodies clean themselves out and start over. It isn’t pleasant, but neither is it frightening, since it happens to everybody at the same time of life.

Somehow, Carmen “caught” it from us, which is medically impossible. Our biologies aren’t remotely related; we don’t even have DNA. Nevertheless, she did have the transition “sickness,” and we brought her back to our home and treated her the way we would a Martian child, having her breathe an unpleasant mixture of smoldering herbs. She expelled everything, especially the two large cysts that had grown in her lungs. She was fine the next day, though, and went home—which was when the real trouble started.

She had apparently infected all the other youngsters in the colony—everyone under the age of twenty or so.

It was all sorted out eventually. Our leader Red and a healer Martian went over to the human colony and treated all the children the way they had Carmen, not pleasant but not dangerous. Unfortunately, no one could explain how the “disease” could have been transmitted from us to Carmen and from Carmen to the children. Human scientists were mystified, and, of course, we don’t have scientists as such.

The children seemed to be all right. But people were afraid that something worse might happen, and so the humans on Earth put all of Mars under quarantine, where it remains to this day, although there have been no other incidents. People who come to Mars do so in the knowledge that they may never see Earth again.