But if the cold wind dropped low, then the hot wind must drop also, and also the shear zone between them. Rarely, it was possible for human eyes to detect the shear zone, and he convinced himself at last that he could see it now, faint whirls of mist, vanishing almost before the eye made them out. His objective, then, was to climb as high as he dared and then glide NailBiter into that valley and hope to ride the hot wind around to the dark side of Eagle Dome.
It sounded simple.
The climb in the thermals was easy; NailBiter did not care, for his lungs could handle the altitude with ease, and perhaps he was even impatient with the rider who held him back, easing gradually to humanly impossible altitudes. The top of Eagle Rock seemed no lower when Shadow reached his nose-bleeding limit and tried a twist of air from the ancient bottle. It smelled foul, and seemed to do very little to clear his head. He risked a few more minutes' climbing and a few more puffs, then signaled for a dive. He probably blacked out briefly after that, but a sudden surge and a torrid breath told him that he had entered the invisible trough of the shear zone.
It was like riding a batted bird--NailBiter was hurled and buffeted and tossed. At times the two of them were turned right around and thrown toward the plains. Then a saving upwelling would loop them over and swirl them back again. Shadow's head throbbed, and his stomach heaved--he had never experienced anything like this before. He suspected NailBiter was enjoying it, but the strain on his wings must be immense. How much of their progress was due to his eagle instinct and how much to Shadow's skill and how much to sheer luck was impossible to know; all they could do was try to climb in the ups and avoid the downs, with neither visible in advance and their mutual boundaries unpredictable--a great game for lunatics.
Just once, and only briefly, they caught a sky wave, a smooth ripple between hot wind above and cold wind below, moving in the right direction, and for a few minutes they rushed in silent flight up the valley. Then it ended abruptly, or they lost it, and it was back to the turbulence again.
Inch by inch, it seemed, they fought their way up the narrowing gorge. The sun sank lower, the plains behind began to shrink, framed between the mountains of the Rand and the flank of Eagle Dome, and the land below was a darkness faintly glimmering with traces of ice.
Yet the topographic valley climbed relentlessly, and the invisible valley in the sky climbed also. Eventually the shear zone was too high for Shadow, and that came just where Ukarres had warned it would: where the valley swung around the mountain and the black bulk of Eagle Dome cut out the sun. The air bottle was exhausted. Shadow put NailBiter into a dive, and they plunged down through the icy wind toward the side of the mountain.
A jagged spur loomed out of the darkness, and he signaled for NailBiter to perch.
He had never experienced such cold; it soaked through his flying suit like ice water--and met the cold of fear working outward. NailBiter clutched fiercely at the rock and hunched down, his feathers fluffed out and rippling in the hurricane. The valley was lit by a dim reflection from immense sun-bright peaks on the High Rand, ragged and taller even than the Dome. On one side the black valley, on the other an equally black cliff stretching up...
Stars! Shadow had never seen stars, but his eyes had adjusted to the dark, and the sky above him glittered with billions of tiny points of light. He had heard of them--and there they were. Even in his terror and exhaustion he was overwhelmed by their beauty. The poets and the ancient texts had never done them justice.
But if he sat and looked at stars for very long, he would freeze to death. Somehow he had to fight his way up the next stretch of this valley. Eventually, Ukarres had said, he would come to a junction, where the torrent of cold wind from Darkside flowed down off the High Rand and split against the back of Eagle Dome. After that, it would be downhill all the way to Allaban. Until then, it was upwind and there were only two ways to travel upwind: on the power of NailBiter's wings or by kiting.
"Let's go, fellow," Shadow said through chattering teeth, and pulled on the reins.
NailBiter did not want to go--he could see no reason whatsoever to fight against the wind into darkness. Food and warmth and his mate were in the other direction, and he balked and argued and struggled and was kicked as he had never before been kicked. The wind would be least strong near the ground, so the first leg was easy--a nearly vertical, ear-bursting dive toward the surface of the glacier to traverse the cold blast as quickly as possible and gain maximum speed for a glide--but after that it was powered flight all the way, NailBiter fighting the wind and Shadow fighting NailBiter.
The glacier itself was a rock pile, with only small traces of ice showing and deadly teeth looming unexpectedly out of the night. Some of the boulders were as large as Hiando Keep, small mountains. Those giants provided lee air and slightly easier flying for a moment--and then made up for the respite with the icy fury of their turbulent edge winds.
Shadow had lost all count of time, and he had no idea how long the battle went on, until he suddenly realized that the ground was right there in front of him, and NailBiter grabbed a rock and stopped. He was finished--a bird could not carry a man far on muscle power. Shadow was lying prone, with his head against the feathered back, and he could hear the pounding heart.
They rested, man and bird, as the wind moaned its triumph and dug ice talons deeper into Shadow's bones. When NailBiter's pulse rate had dropped to a more normal level, Shadow moved to the next stage. He took a sheep's leg from his baggage and tossed it forward.
Snap!
Two minutes later they were airborne once more--the mutton had been doped with a trace of batmeat. In very small doses it acted as a stimulant. That was how his predecessor had died, he remembered, when some young aristocrat had tried the trick while in the prince's company. The difference between stimulation and madness was razor-narrow, and now he risked the same fate as Vindax, if he and Vonimor had misjudged the amount.
But even batmeat had its limits. Four times he doped his eagle and NailBiter surged forth with new strength. But Vak and Shadow had agreed that four was the most they could risk--a dead bird would be of little use. The final dose produced only a short progress, from which NailBiter took a long time to recover, crouching low to his rock and trembling violently. He could fly no farther.
The frozen desert of dark and rock and cold still held them, sloping more steeply now, but still they had not reached the crest of the pass. There was only one desperate measure still to try.
"Good old buddy," Shadow said. "You've done your best. Now for a new trick."
NailBiter had never been taught kiting; Shadow had never seen it done. He untied his coil of rope and grapnel, slid from the saddle, and started to walk, scrambling in the dark over the boulders. Every step was a torment for tortured lungs, and he needed to stop frequently just to get breath.
When he guessed that he had come far enough, he wedged the grapnel between two rocks and started to return, paying out rope, stumbling, falling, panting...Idiot! He should have tied the other end first. What if he could not find the bird? The thin air was shriveling his brain.
But he did find NailBiter, and with fingers already numb inside his mitts, he fastened the other end of the rope to the saddle girths. He threw the rest of it loose on the ground, climbed aboard again, and took a hard grip on the end closest to the grapnel.
"Okay, Naily," he muttered. "Let's kill ourselves."