Free Chronicles of the Red King #3: Leopards' Gold by Jenny Nimmo

Melyntha.
    “But what if the crystal isn’t there?” said King Timoken. “We can’t attack without a reason. I don’t doubt that the eagles saw Rigg and his abductors on the castle road, but we need more proof. The crystal might still be here, hidden by whoever took it.”
    John, the guard, might have told them more, but he had inconveniently escaped. The soldier who had been guarding him was overcome in the middle of the night, knocked senseless by a blow to his head. His keys had been taken and John set free.
    The stricken soldier wasn’t discovered until morning. It was feared that he might never regain his senses.
    Never before had the king and his court had so many problems to deal with. In the meantime, with everyone in the castle so distracted, Vyborn discovered how to have fun. Encouraged by Olga and Lilith, he practiced his new shape-shifting talent almost the whole day long.
    The boys in Vyborn’s bedchamber were kept awake all night by boar grunting, owl hooting, bat screeching, and donkey braying. Wings scratched their faces, tusks pulled off their covers, and the donkey seemed to fill every space in the room with its great head and rough-haired body.
    “Perhaps it’s not a donkey,” Petrello muttered, burying his head under his pillow.
    It was a dark night and Vyborn’s shape-shifting couldn’t be seen. There were only the familiar animal sounds to suggest what was going on.
    “I’ll bet you can’t become a quiet creature like a cat,” said Tolly, hoping Vyborn would take up the challenge.
    “Cats aren’t always quiet,” said Gunfrid, who was sharing Tolly’s bed.
    There followed several moments of grunting and sniffing. Fingernails scraped the floor, a heavy object rolled and scratched and struggled. Something banged against Petrello’s bedpost. What was going on?
    All at once, the moon swam out from the gray cloud that had buried it, and Vyborn’s human shape could be seen. The light on his face was eerie and cold, and the voice that came from him was an awful, yearning, resentful sound.
    “I can’t,” said Vyborn, through gritted teeth. His dark, fathomless eyes glared up at Tolly. “Why did you say a cat?”
    “Just a thought,” said Tolly.
    “No,” barked Vyborn. “You guessed I couldn’t. I tried to be a leopard, but I couldn’t. Why?” He looked up at Petrello, who had removed the pillow from his head.
    “How should I know?” said Petrello.
    “Why? Why? Why can’t I be a leopard?”
    “Leopards are very, very special.” Guanhamara stood in the doorway, a lantern swinging from her hand. “Leopards are creatures that can never be used by ‘things’ like you, Vyborn, and you’d better get used to the idea.”
    “S-s-s-s-k-k-k-gr-gr-gr!” Vyborn’s voice went through a series of unidentifiable animal noises. The sounds ranged from a quiet squeak to a deafening roar. And it was while he was roaring that his face and body began to change into a big, featureless lump, a creature that never was, and never could be.
    The dark shape lumbered toward Guanhamara, but she stood her ground. “I’m going to have to teach you a lesson, Vyborn,” she said, her voice very stern.
    The lump hesitated. It grunted and sniffed the air. And then it shrieked. Everyone else screamed.
    There, standing just inside the door, was a tall, white, writhing monster: a demon with two heads, its eyes red embers, its open mouth awash with fangs, its arms scaly, its fingers bloody.
    Petrello knew it had to be one of his sister’s illusions, but he couldn’t stop himself from screaming.
    It was the middle of the night. Bloodcurdling screams were bound to cause a stir. But by the time Nurse Ogle appeared on the scene, Guanhamara had tiptoed away, the ghostly demon had dematerialized, and Vyborn’s head was under the covers.
    “What’s going on?” Nurse Ogle demanded. “Are you causing trouble again, foolish Petrello?”
    “I am not,” said Petrello indignantly.
    “He is not,” said