There were lights somewhere up there in the spoke. He supposed they were the windows he had read about. From here they dwindled like runway lights seen from a landing plane.

He gradually became aware of a more immediate light, to his left and over his head as he reclined on the deck. He sat up and turned around and saw that the surface of Nox was being lit from below with a pearly blue luminescence. At first he thought it was a hive of the sea insects Cirocco had told him about.

"It's a sub," said a voice to his right. He was startled; Cirocco had joined him silently. "I sent messengers a few hours ago, hoping to attract one. But it looks like she'll be too busy to give us a tow." She pointed at the sky to the west, and Chris found a big patch of deeper darkness against the night. He didn't need anyone to tell him it was a blimp, and a big one.

"Not many people have seen this," Cirocco said quietly. "There aren't any subs in Hyperion because there're no seas. Blimps go anywhere, but subs stay where they're born. Ophion won't hold them."

There was a piercing series of whistles from the blimp, followed by a sizzling and hissing from the rear of Constance. Chris understood that the blimp had asked for the fire to be put out, and the Titanides had complied.

He felt Cirocco's hand on his shoulder. She pointed over the water. "Right there," she said. He looked, still conscious of her hand, and saw tentacles writhing upward, thrashing slowly against the water. A slender stalk rose from the mass of them.

"That's her periscope eye. This is about as much of a sub as you'll ever see. Notice the long swelling there on the water? That's her body. She never comes out any more than that."

"But what's she doing?"

"Mating. Be quiet, don't disturb them. I'll fill you in."

The story was straightforward, though not obvious. The blimps and subs were male and female of the same species. Both descended from the sexless children of their union, which were snakelike and nearly brainless until competition had reduced their swarms to a small number of twenty-meter survivors. At that point they grew a brain and tapped some racial source of knowledge that neither Gaea nor the blimp-subs had ever explained to Cirocco. It had nothing to do with nurturing, for from the time they were spawned neither the mothers nor the fathers had anything further to do with them.

But they grew wise in some mysterious way, and eventually made a conscious decision to become male or female, blimp or sub. Each entailed a hazard. The water contained many predators which ate young subs. There was no such risk in the air, but a young blimp could not manufacture his own hydrogen. His fate after metamorphosis would be to sit on the water, an empty bladder, and hope a mature blimp would, so to speak, blow him up. No adult could support more than six or seven in his squadron. If there were no openings, it was just too bad. The decision to differentiate was irrevocable.

The blimps and subs had little to do with each other. They might never come together at all at the watery interface between their worlds but for two facts. There was a species of seaweed that grew only in deep water; without it, the blimps could not survive, and the Titan trees-massive spurs of the body of Gaea herself, growing more than six kilometers tall and only in the highlands-sprouted leaves near their tops which were vital to the diets of subs.

Amicable mating was in the interest of both sexes.

Something fell from the tendrils which dangled below the midships bulge on the great curve of the blimp's belly. It splashed into the water. The sub's tentacles gathered it in and made it vanish. There was a deep sigh as the blimp vented hydrogen and sank toward the outstretched arms of his lover.

Beyond that there was not much to see. The tendrils entwined and the massive bodies touched at the surface of the sea, and they just stayed that way. It was only when waves began to roll the raft that Chris realized how much activity might be concealed by distance.

"There is a lot happening," Cirocco confirmed. "There is a way to get closer to the action, by the way. I was once a passenger in a blimp when he got smitten by love. Let me tell you ... never mind. It's a rough ride."

Cirocco went away as quietly as she had come. Chris continued to watch. Before long he heard hooves on the deck, and Valiha came around the cabin to join him. He was sitting on the edge of the raft, his feet dangling over the side to just reach the water. Valiha sat the same way, and for a moment a trick of the shadows made the equine part of her body vanish. She became a very big woman with shrunken, spindly legs, dangling her devil's feet in the water. The image upset him, and he looked away from her.

"Beautiful, isn't it?" she asked, in English so singsong that for a moment he thought she had sung it in Titanide.

"It's interesting." In truth, he was beginning to tire of it. He was just about to get up when she took his hand, raised it to her mouth, and kissed it

"Oh."

"Hmmm?" She looked at him, but he could not think of anything to say. It apparently didn't matter. She kissed him on the cheek, the neck, and the lips. He took a deep breath when he was able.

"Wait. Valiha, wait." She did, looking at him with her great, guileless eyes. "I don't think I'm ready for this. I mean... I don't know what to tell you. I just don't think I can handle it. Not now." She continued to search his eyes. He wondered if she was looking for madness, decided that was his own fear speaking. At last she briefly pressed his hand between both of hers, nodded, and let him go. She stood up.

"Let me know when you are. Okay?" She hurried away.

He felt bad about it. Though he tried to analyze his reasons for rejecting her, nothing satisfied. Partly Valiha was a reminder of something he had done while possessed. He was a lot braver at those times, unless he was a lot more timid. It looked as if that had been a brave time because try as he might, he could not come up with a comfortable answer to one question: what did a Titanide and a human do? And another: how much life insurance would he need before attempting it?

Valiha was big. She scared him to death.

It might have been fifteen minutes later that Gaby came around the side of the cabin and joined him in the bow. He only wanted to be alone with his thoughts, but his hideaway was turning into a parade ground.

She leaned on the rail, whistling, then nudged him.

"Feeling the blues, buddy?"

He shrugged. "It's been a weird eight hours or so. You think something's in the air?"

"Like what?"

"I don't know. Everybody's in love. Out there the sky's in love with the sea. Back onshore I found myself acting foolish over Robin."

Gaby whistled. "Poor boy."

"Yeah. Just a few minutes ago Valiha wanted to pick up where my mad alter ego left off, shooting marbles, as they say." He sighed. "It must be something in the air."

"Well, you know what they say. It makes the world go around. Love, that is. And Gaea spins a hell of a lot faster than the Earth."

He looked at her suspiciously. "You didn't have anything... ."

She held her hands up and shook her head. "Not me, friend, I won't bother you. With me, it's once in a blue moon, and usually with girls. I don't go in for the short-term stuff either. I want all my relationships to last. All seventeen of them." She made a face.

"I guess you have a different perspective on it," Chris ventured. "Being as old as you are."

"You'd think so, wouldn't you? Not true. It always hurts. I want it to last forever, and it never does. And it's my fault. I always end up measuring them by Cirocco, and they never measure up." She coughed nervously. "Well, listen to me. I didn't mean to get into that. I came to stick my nose into your business. You don't have to be afraid of Valiha. Not emotionally, if that's what's bothering you. She would not be jealous, or possessive, or expect it to last long. Titanides have no concept of exclusiveness."