Guards! Guards!

his hand clamped over Errol’s muzzle. The little dragon was whimpering like a kicked puppy, and fighting to get away.
    “It’s a magnificent brute,” said Lady Ramkin, in what she probably thought was a whisper.
    “I do wish you wouldn’t keep saying that,” said Vimes.
    There was a scraping noise as the dragon dragged itself over the stones.
    “I knew it wasn’t killed,” growled Vimes. “There were no bits. It was too neat. It was sent somewhere by some sort of magic, I bet. Look at it. It’s bloody impossible! It needs magic to keep it alive!”
    “What do you mean?” said Lady Ramkin, not tearing her gaze from its armored flanks.
    What did he mean? What did he mean? He thought fast.
    “It’s just not physically possible, that’s what I mean,” he said. “Nothing that heavy should be able to fly, or breathe fire like that. I told you.”
    “But it looks real enough. I mean, you’d expect a magical creature to be, well, gauzy.”
    “Oh, it’s real. It’s real all right,” said Vimes bitterly. “But supposing it needs magic like we need, like we need…sunlight? Or food.”
    “It’s a thaumivore, you mean?”
    “I just think it eats magic, that’s all,” said Vimes, who had not had a classical education. “I mean, all these little swamp dragons, always on the point of extinction, suppose one day back in prehistoric times some of them found out how to use magic?”
    “There used to be a lot of natural magic around once,” said Lady Ramkin thoughtfully.
    “There you are, then. After all, creatures use the air and the sea. I mean, if there’s a natural resource around, something’s going to use it, aren’t they? Then it wouldn’t matter about bad digestion and weight and wing size and so on, because the magic would take care of it. Wow!”
    But you’d need a lot , he thought. He wasn’t certain how much magic you’d need to change the world enough to let tons of armored carcass flit around the sky like a swallow, but he’d bet it was lots.
    All those thefts. Someone’d been feeding the dragon.
    He looked at the bulk of the Unseen University Library of magic books, the greatest accumulation of distilled magical power on the Discworld.
    And now the dragon had learned how to feed itself.
    He became terribly aware that Lady Ramkin had moved, and saw to his horror that she was striding toward the dragon, chin stuck out like an anvil.
    “What the hell are you doing?” he whispered loudly.
    “If it’s descended from the swamp dragons then I can probably control it,” she called back. “You have to look them in the eye and use a no-nonsense tone of voice. They can’t resist a stern human voice. They don’t have the willpower, you know. They’re just big softies.”
    To his shame, Vimes realized that his legs were going to have nothing to do with any mad dash to drag her back. His pride didn’t like that, but his body pointed out that it wasn’t his pride that stood a very reasonable chance of being thinly laminated to the nearest building. Through ears burning with embarrassment he heard her say: “Bad boy!”
    The echoes of that stern injunction rang out across the plaza.
    Oh gods, he thought, is that how you train a dragon? Point them at the melted patch on the floor and threaten to rub their nose in it?
    He risked a peep over the horsetrough.
    The dragon’s head was swinging around slowly, like a crane jib. It had some difficulty focusing on her, right below it. Vimes could see the great red eyes narrow as the creature tried to squint down the length of its own nose. It looked puzzled. He wasn’t surprised.
    “Sit!” bellowed Lady Ramkin, in a tone so undisobeyable that even Vimes felt his legs involuntarily sag. “Good boy! I think I may have a lump of coke somewhere—” She patted her pockets.
    Eye contact. That was the important thing. She really, Vimes thought, shouldn’t have looked down even for a moment.
    The dragon raised one talon in a leisurely fashion and pinned her to the ground.
    As Vimes half-rose in horror Errol escaped from his grip and cleared the trough in one leap. He bounced across the plaza in a series of wing-whirring arcs, mouth gaping, emitting wheezing burps, trying to flame.
    He was answered with a tongue of blue-white fire that melted a streak of bubbling rock several yards long but failed to strike the challenger. It was hard to pick him out of the air because, quite clearly, even Errol didn’t know where he was going to be, or