Mach stared after her. What was the problem? She had seemed so vigorous and cheerful during the climb, completely recovered from her hard run of two days before. There was no evidence of pursuit at the moment. Why should she have to leave him now, if she didn't want to?

He ate his fruit and rested, admiring the countryside. She would surely tell him in due course, and meanwhile this was about as nice a region as he could imagine. He had never had physical experience with either mountains or forests before, there being only holo representations of such things in the dome-cities of Proton, and he liked them very well. The hill sloped gradually down to the south, and then the nearest segment of the Purple Mountain range heaved up to an extraordinary elevation, the highest peak spearing a cloud and anchoring it so that it could not drift away.

Actually, it wasn't just the terrain that exhilarated him, he realized. It was the living body. He had discovered that eating was not the nuisance he had imagined it to be, when in robot body; it was a pleasure. In Proton, as a robot, he had lacked the sense of taste, it being unnecessary to his survival; here it was a glorious perception. Even the complication of periodic elimination was not really bothersome, once he knew how to handle it expeditiously. The rest of it was wonderful: the feel of the wind against his skin, the pleasure of healthy exertion, the sheer satisfaction of slaking thirst. The act of living was a dynamic experience.

Fleta returned and changed to girl form. "There be a good path ahead," she reported. "There be a dragon to the east, but it moves not from its stream; an we steer clear o' that, no problem."

Mach looked at her. "What about this matter of-" he began, but then sheered off, deciding not to press the mystery of her need to leave him. "Clothing? How is it that you have no clothing in animal form, yet do now? Where does it go when you change?"

She laughed with a certain relief, as if she had feared another type of question. 'That be no mystery, Mach! I wear clothing in all three forms. In one it be called feathers, and in another, hair."

So simple an answer! And it seemed that anything she carried with her in human form she carried with her in animal form, transforming it to feather or fur.

They resumed their travel. But Fleta seemed increasingly uneasy. Something certainly was bothering her.

In the hollow between the slope of the foothill and the slope of the mountain, she turned to him with a strange expression of hunger. Suddenly he remembered his fear of the unicorn, the first night, not knowing what it fed on. As it had turned out, unicorns were herbivores; his concern had been groundless. But now- "Are you all right, Fleta?" he asked nervously.

"I think I must leave thee now," she said tightly. "I had hoped to see thee safely o'er the mountain, but that must needs wait."

"Fleta, where do you have to go?" he asked.

"To the herd I was destined for, before I met thee."

"Well, of course you can go there, if you wish! But why right now?"

"Mayhap I can go, and return in a few days to see thee the rest of thy journey. Thou shouldst be safe here."

"Well, yes, if that's the way you feel! But-"

"It be fairest to thee." She looked about. "There be fruit trees ahead, and so long as thou dost not go east to the river, and dost avoid being spotted from the air-"

"Fleta, please tell me why! Have I given you some offense? If I am too much of a burden-if I'm not doing enough-"

"I see I must needs tell thee. I must go to the stallion to be bred."

"Right now?"

She made a wan smile. "As soon's I can reach him. It be a fair distance."

"Another long run? You'll wear yourself out! Can't it wait for a more convenient time?"

"Mach, must I speak more directly than I like. With thy kind, breeding be at convenience. Not so with my kind. When a mare dost come into heat, she must be bred; she doth have no choice. Be she in the wrong herd, the local stallion must do it; no choice for him either. That be why I could not approach mine own Herd in this time."

Mach remembered what he had learned of horses and other animals. The females came into heat at intervals, and bred compulsively. They had no interest in such activity at any other time, but were desperate for it then. Fleta was an animal and so followed this pattern. She had seemed so much like a human being, especially because she had remained most of the time in her human form, that this aspect of her nature had not occurred to him.

"Now at last I understand why you had no concern when we went naked," he said. "When you-saw me aroused. You knew that-that breeding occurs only within a creature's own species. So you had no interest in-" He found himself beginning to flush, and didn't care to discuss it further.

"That be but a half truth, Mach," she said. "I would fain have played with thee as I did with Bane in years o' yore. But it be not seemly, when the parties are of age to know better."

"Yes, of course. We are two different species. There can be no such thing between us." He sighed. "Go and do what you must, Fleta; I will wait for your return."

"Aye." But she did not move, and he saw her lower lip trembling again.

"What's the problem, Fleta? Don't worry about me; I'll be fine, here."

"I fear for thee nonetheless," she said. "If the goblins spy thee-"

"I'll take that chance! Please, Fleta, don't let me interfere with your life any further!"

"O, I wish there were the right plants in these mountains!" she exclaimed.

"Plants?"

"Herbs. We eat them at need, to suppress the cycle."

"Oh."

"O Mach, I love thee and would not leave thee vulnerable to the dangers of Phaze. I want to leave thee not!"

Mach took a step toward her, his arms outstretched, intending to comfort her, but she backed hastily away. "I dare not touch thee now!" she whispered.

"But I mean you no harm, Fleta!" he protested.

"Dost thou not see-it be thee I would be bred by, not some stupid stallion!"

Mach was stunned. "But-but I'm not your species! We agreed that it was not proper for us to-"

"Aye, we agreed," she said, biting her lip. "And no way it would take. I be a pighead even to say this, but-"

"Are you saying-you and I-?"

"The body knoweth not; it thinks one breeding be as good as another. I could stay with thee till the time pa.s.s-"

"Stay-and-?"

"Dost despise me now?" she asked, her face wet with tears. "Fain would I ne'er have had thee know, but me-thought I could get thee to safety before-"

Mach worked it out aloud, to be sure there was no misunderstanding. "If you and I tried to breed, nothing would come of it because of the difference in our species. But then you would not have to run off to the stallion. You could stay with me."

"That be my thought. I know I have no right-I know it be wrong-"

"Fleta, I come from a different culture. Robots and androids and human beings-we do this sort of thing all the time, knowing none of it can take. I myself am the offspring of an impossible marriage between a man and a machine. I have not-not tried to engage in-not with you, because-I understood you did not want it!"

"Ne'er did I say I wanted it not," she said. "I said it should not be. I spoke not for myself, but for my culture."

"Then we have no problem!" he exclaimed. "I have have longed for-if I had realized-"

"Then-thou wouldst do it?"

"Just tell me when!"

Something gave way in her. "Now?" she asked faintly.

Mach stepped toward her again, and this time she did not retreat. "Now and forever!" he cried.

They came together, and he discovered in a moment that this was no ordinary tryst. He tried to kiss her, but she was too busy trying to tear off his clothing and her own. All she wanted was one thing, and she wanted it instantly.

They did that one thing, but such was the urgency and haste of it that it was not, for him, the fulfilling experience he had antic.i.p.ated. He lay beside her on the leafy ground, his clothing half off, her cloak the same, and wondered whether that really could be all there was to it, in the living state. No preliminaries, no caressing, no speaking, not even kissing; just the straight, raw thrust of it. Yet of course she was an animal, and this was the way her kind did it, regardless of the form a.s.sumed. He should have known.

She turned to him, on the ground. There were twigs in her hair, and dirt was on her b.r.e.a.s.t.s. "Mach?"

"Yes?"

"Canst-again?"

"Again? Now?"

As a robot, Mach could have done it; as a living creature, he found it difficult. "Um, let's work up to it a bit more slowly, this time," he said.

"But I need it now!" she protested. To be in heat: to have a temporary but insatiable appet.i.te for s.e.x. He understood this intellectually, but his body could not keep the pace.

"I'll try," he said.

He tried, and to his surprise found he was able. The body was young and healthy, and the mind retained desire. This time the culmination was slower, but she seemed satisfied.

He relaxed, glad he had gotten through. She would not have to charge off to the herd.

But in a few minutes she stirred again. "Canst-?"

"Fleta, there is only so much flesh can do!" he cried.

"But an it not do more, must needs I seek the stallion-and this I want not!"

Because her body governed this need, not her mind. Mach would have found this baffling, had he not had his own experience with involuntary arousal.

So Mach tried again. This time he made a production of it, deliberately kissing her and playing with her b.r.e.a.s.t.s and stroking her body. She tolerated this, but it was not her interest; she craved the breeding, nothing else. Finally he was able to do it a third time, and then she relaxed.

But too soon she stirred again. "Canst-?"

Mach lurched to his feet. "Must-urinate," he said, and headed for the bushes.

In the bushes he did what he said he would do, but his mind was elsewhere. He had thought that one or two acts would satisfy the need; now he knew that the need was as far beyond his means as the galloping travel across the plain had been. Yet Fleta was under the control of her cycle; she had to be bred, as she put it, and if he could not serve in lieu of the stallion, she would be compelled to seek that stallion. He had to find a way to accommodate her, at least until her cycle moved on.

He gazed at his limp anatomy. This was hopeless! Then he had a notion. He worked it out in his head, and then hummed to summon his magic. "Grant me the skill to perform at will," he sang, thinking of s.e.x.

The fog formed and dissipated-and abruptly his potency was restored. For once his magic had worked the way he wanted!

He strode back to Fleta. Without a word he took her in his arms and did what she wished. There was no special joy in it; the spell merely made him potent, not satisfied. Perhaps that was why it worked, he realized: he now had no more satisfaction in the act than she did therefore was never satiated. Then, before she could stir again, he did it again. And again. He was magically competent.

Finally, after half a dozen repet.i.tions, she was satisfied. She embraced him and slept. He relaxed, but his anatomy did not. Sure enough, in half an hour she woke, wanting more.

So it was for the afternoon, and the night, and the following morning. Finally, in the afternoon, her cycle moved on, and she needed no more from him. It was Mach's turn to sleep the sleep of exhaustion, as the energy drained from his body by the potency spell had to be restored. If Fleta had run hundreds of kilometers in an afternoon, he had performed a similar feat.

They resumed their journey, climbing the great Purple Mountain. But now some of the urgency was gone. Why was he going to see the Brown Adept? Mach asked himself. To find out how to return to Proton? What, then, would become of Fleta? To escape the pursuit by the various monsters? They seemed to be free of it here. Yet if he did not go-if he just stayed here-what of Bane, whose body and world these really were? He had no right to think only of himself.

Fleta paused, looking at him. "Thou'rt all right?"

"Just wishing I could stay here forever, with you. But that would be at Bane's expense."

"Aye. And he be an apprentice Adept. Our love be not for eternity." She looked so forlorn as she said it, that he had to take her in his arms and kiss her. This time she responded warmly.

"Funny thing," he said. "Yesterday, when-you wouldn't kiss me."

"This be love," she said. "That be breeding."

"But can't the two be joined?"

Her brow furrowed. "They be two different things!"

"Not in my frame."

"What a funny frame!"

"I suppose so." What point to debate it with her? Her nature did not equip her to understand.

They found a niche to spend the night, well up the mountain. After they had eaten, and the darkness closed in, Mach brought up the question of the afternoon again. "When you're out of heat, you don't seek s.e.x," he said.

"Aye. It be pointless, then."

"But can you do it?"

"Can, aye. Did, as game with Bane. But why?"

"Because I prefer to combine love and s.e.x. That's the way it is, with human beings."

"But when it be impossible to breed-"

"When we did it, it was impossible to breed. But we did it anyway, for another reason."

'To prevent me from running away," she agreed. "And glad I am that thou didst manage that, Mach! But now there be no danger o' that."

"So even your kind can do it for other reason than for breeding."

She considered. "Aye."

"I'd like to do it for other reason now. For pleasure."

"Why of course, Mach, an it please thee! It meaneth naught to me, other than as a game." She hiked up her cloak and spread her legs. "But be not long about it, so I can sleep."