A fit gripped Angelo and his whole body started to shudder and convulse. His arms dropped to his sides, shaking wildly along with the rest of him.

Odin's arm hadn't lowered at all, but the tips of Angelo's toes were now scuffing against the floor. The Allfather's face was turning red, as if the effort of holding the boy aloft was taking all his strength. The soles of Angelo's feet touched the ground, although Odin still hadn't moved a muscle.

That was when Zac realised a" he was growing. Angelo was growing. In that moment, something inside Zac's head went click.

Jekyll & Hyde. A whole shelf full of Jekyll & Hyde. Gabriel had said Angelo was only half angel.

But he never said the other half was human.

Zac shuffled a few centimetres backwards on his knees, until he could retreat no further.

One of the Vikings beside Odin pointed at Angelo's face. He laughed, but the sound was nervous and uncertain. "He's going an awfully funny colour, Allfather," he said.

"Is anyone hot in here all of a sudden?" asked another of the Norsemen.

And at that, all Hell broke loose.

NGELO'S FINGERS BALLED into tight fists, then opened again suddenly. Smoke trailed from his blackened nails.

The T-shirt he was wearing split down the back as the boy's frame filled out. A jagged row of blood-red spikes tore through his skin along the length of his spine. He hurled back his head and screamed, spewing fire in a mushroom cloud above him.

As one, the Vikings shuffled back. Odin tried to maintain his grip, but Angelo was growing exponentially, and soon his neck was too broad for the Allfather to hold on to.

There was another rip as the sleeves of the shirt surrendered to Angelo's bulging biceps. His toes distended, sprouting curved black claws. The plastic straps of his flip-flops snapped as his feet rapidly outgrew them.

His skin too was changing. It wasn't just the colour a" now a reddish-brown, like dry desert mud a" it was the texture too. Rough, coarse scales covered his flesh, like a fish with a bad case of psoriasis.

Odin's eye swivelled up and down as he examined the creature that now towered above him. "A dragon!" he announced.

"A demon," Zac corrected. The Vikings holding him had loosened their grip. He pulled free and jumped to his feet, but they were too startled to try to catch him.

At the sound of Zac's voice, the Angelo-demon whipped round. Fire burned in the hollows of his eyes, and Zac knew in that instant that Angelo wasn't at home any more.

"A challenge!" Odin bellowed. He stooped to retrieve his axe. "How long have I waited for a moment such as this? I say we battle. What say you, dragon?"

Angelo's jaws opened, revealing several hundred needle-like teeth. He let out a deep, guttural roar, and a blast of flame hit Odin in the face.

The Allfather blinked. "Right, then," he mumbled, patting down the embers in his smouldering beard. "I'll take that as a yes."

The thing that had been Angelo was still transforming. The spikes down his spine now continued along a twisting tail. It tore through the back of Angelo's trousers a" which miraculously were still more or less in one piece a" and flattened into an arrowhead point at the end. The tail gave a faint boing as it reached its full impressive length.

Odin, who had mere moments ago seemed enormous, was now dwarfed by the demon. Angelo's head hung low and his broad, scaly shoulders were stooped, but even hunched over he was at least four metres tall. Taller, if you included the horns jutting up like elephant tusks from the top of his head. His ears were pointed and elf-like. His nose was flat, spread across his face like a clumsy boxer's.

"Right, then, Dragon!" Odin bellowed. "What say wea"?"

The sole of the Angelo-demon's foot slammed against Odin's armour. Vikings were scattered like skittles as the flailing form of the Allfather cannoned backwards across the hall. Those still on their feet watched as Odin was driven clean through the wall and into the snowy wilderness beyond.

For a moment, there was no sound, save the falling of plaster and the swirling of wind through the newly formed hole. Then, from somewhere in the crowd, there came a battle cry. It was hesitant and uncertain, but it was a battle cry all the same. Others soon followed.

"Slay the dragon!"

"Cut off its head!"

"Stop talking about it!" roared one of the Norsemen. "And just kill the thing!"

He and some of the Vikings nearer the back of the crowd began to push forward. They shoved with an enthusiasm reserved for those who know full well that there are several dozen other people between them and anything dangerous.

Those Vikings who were unfortunate enough to be near the front were much less gung-ho. They had seen the full horror of the creature, they had felt the searing heat of its breath and they had decided that while they might already be dead, this thing could almost certainly make them deader.

The crowd heaved, half of it pushing forward, the other half pushing back. Those pushing forward had managed to seize the element of surprise, though, and the throngs quickly began to tighten round Angelo.

With an inhuman screech, he swung a scaly arm, batting half a dozen Vikings into the air. Even before they landed, he was sweeping his other arm out in a wide arc. Ten, twenty, thirty Norsemen crunched down across the room.

Those pushing from the back did some quick mental calculations and realised they didn't have nearly the number of human shields they'd had a moment ago. They hesitated, their swords no longer waving so enthusiastically, their shouting now barely audible over the cries of their kinsmen.

Roaring, Angelo smashed both enormous fists down on to the floor. The ground quaked, yet more Vikings fell, and for the first time since they had been erected, the walls of Valhalla began to tremble.

Over the sounds of the screaming and the roaring, Zac heard another sound. It was a high-pitched whistling, like something slicing through air. He looked up to see one of the shields from the ceiling zipping towards him, and leaped sideways in time to avoid being sliced cleanly in two.

With a metallic ba-doing, the shield embedded itself several centimetres into the stone floor. It was a decorative piece, too large for even Odin to wield in battle, and as Zac looked up he thought he saw Herya scuttling away from the space where the shield had been hanging.

Cupping his hands round his mouth, he shouted to the Valkyrie lurking somewhere above. "Oi, watch out! That nearly hit me!"

Another shield began to fall. It flipped over, mid-plunge, and landed face down on the stone right beside Zac. The clang rang out like the tolling of a church bell. The echo lapped the hall half a dozen times, before fading away.

"And again!" Zac shouted. "What are you doing? Trying to kill me?"

Zac felt a gust of warm breath breeze over him. Angelo had turned away from the Vikings and now stood glaring down at him, shoulders hunched, fists clenched.

"Oh... hi," Zac offered as brightly as he could. The fire danced higher in the demon's hollow eye sockets. It opened its wide jaws, and Zac saw something spark at the back of the cavernous maw.

He swore then, loudly and creatively, but the words were drowned out by the crackling of the flames from Angelo's throat. Zac dived and tucked himself in behind the upright shield just as the inferno hit. He felt the metal go red-hot; coughed as his lungs filled with the tang of fire and brimstone.

There was a hiss from the floor. Zac looked down to see drops of molten gold pooling together on the cool stone. He looked up. The flames were still licking over the top and round the edges of the shield, melting his defences away.

"Stop!" he wheezed. "Angelo, stop."

But Angelo was no longer listening, because Angelo was no longer there. Only the demon remained, scaly and sizzling and a" Zac hated to use the word a" hulking.

Gold flowed in rivers round his feet. The shield was little more than a gleaming wafer now. Zac's time was up.

"DRAGON!"

The word raced round Valhalla, deep and booming and oh-so-very angry. With a whoosh of inrushing air, the fire stopped.

A moment later, what was left of the shield became a shimmering sludge on the floor, and Zac saw a demon turn to face a god.

Odin was standing at the far end of the long wooden table, axe in hand, several centimetres of snow piled up on top of his helmet. His white beard was dark with soot, but his expression was darker still. He flipped up the patch with the surprised eye drawn on, revealing a fourth and final patch beneath. The eye drawn on this one scowled furiously, with flecks of red painted at the centre of the pupil.

With one hand he swung the axe down on the table. The wood split along its entire length, and the two halves fell neatly in opposite directions. Odin began a slow march along the newly formed path, and with each step the god took, Zac felt his ears go pop.

"I welcomed thee into my home, Dragon, and you repay me thus?" Odin growled. He ground his teeth together and tiny blue sparks spat from his mouth. "You attack my Viking brothers. You destroy the Great Table."

"Um, actually, I think that was you, Allfather," whimpered a voice from somewhere beneath a pile of groaning Vikings. "To be fair."

"And you defy the all-powerful Odin," continued the god, ignoring the interruption. "Here in Valhalla. Here in Asgard, you defy me!"

Odin was halfway to the demon now. The handle of the axe creaked as he tightened both hands round it. "I, who have slain giants in my sleep. I, who created all of Midgard from the blood, bones and flesh of my fallen enemies."

He stopped just a few metres away from the monster. "I, who has a dirty great axe and a very short temper."

The few Vikings who were still intact and fully operational gave a cheer at that, but it was a cautious one, as if they weren't completely sure that Odin was going to win. The last thing they wanted was to get any further into the demon's bad books.

"Thou hast put a right bloody dampener on an otherwise fine afternoon, Dragon. And for that thou shalt die!"

HE THING THAT had until just a few moments ago been Angelo, vomited Hellfire in the Allfather's face. The flames licked hungrily across the old god's weathered skin, turning his eyepatch black and melting the snow that had been balanced on his head.

Although he was several metres away, the heat forced Zac to draw back. Odin growled with pain, but otherwise didn't flinch. He raised the axe before him, using the flat of the blade to block the worst of the fire.

Angelo's tail flicked around like a striking cobra and his clawed fingers curled into fists as, step by agonising step, Odin advanced.

Zac kept his distance and just watched. For the first time in as long as he could remember, he had absolutely no idea what to do. He'd spent a lifetime thinking on his feet, finding solutions to problems before they even happened. Now, though, standing in a mythical land, watching a Norse god fight a transforming angel-demon, he was fresh out of ideas.

As he drew close to the demon, Odin swung the axe in an upwards curve. The blade clipped the brute on the chin, snapping his head back and making him shriek and howl furiously.

The Vikings cheered, but Odin's brow knotted when he saw the blade hadn't cut through the scaly skin. He swung again, hacking this time at the demon's barrel-like ribcage. The blow struck like a battering ram smashing against rock. The Angelo-thing staggered, but the axe had failed to draw blood once again.

"What manner of creature art thou?" Odin wondered, before four jagged knuckles crunched into his nose, splattering it across his face. With a roar as savage as any the demon had made, Odin hurled himself forward, letting the axe fall to the floor.

The demon lashed out with its arms and tail. It opened its mouth to cough up more flame, but Odin's hands clamped round its jaws, pinning them shut.

"Let's see you do your fire trick now, Dragon!" cried the Allfather. Fury was etched into every line of his face, but there was something else there too, beneath the blood and the beard a" a bloodthirsty joy. The Allfather was loving every minute of this.

Thrashing wildly, the monster stumbled, a fireball stuck somewhere near the back of his throat. Zac moved quickly from their path, as god and demon crashed towards the wall, then carried on crashing right through it.

There was a hiss of steam as the demon's fiery hide hit the snow, and then both combatants were sliding down the hill, each raining blows on the other as they ploughed a trench through the melting slush.

Zac rushed to the hole in the wall and looked out. Angelo and Odin were twenty metres away already, and they were still picking up speed. He looked ahead of them, down the slope. There, just beyond where it levelled out, Asgard dropped sharply off into nothingness. They were hurtling towards the edge, and they didn't even realise.

"Angelo, look out!" he shouted, but they were too far away to hear, and there was no saying the demon could even understand a word he was saying.

There was a soft whoosh and Herya appeared beside him. "We have to get out of here," she said.

"Stopped dropping shields on me now, have you?" asked Zac, still watching Odin and Angelo sliding down the hill.

Herya caught him by the arm and pulled him away from the wall. "I was saving you from the demon's fire."

Zac's feet splashed through the puddle of melted gold. "OK, I'll give you that one."

She bundled him towards the second shield, which sat like a wide plate on the flagstone floor. "This one's for our escape."

"Escape?" said Zac, then he realised that Jurgen and the other Vikings were closing in round them, weapons drawn. They looked far from happy. "Oh, yeah. Escape."

"There will be no escape for you," Jurgen growled.

"We were having a lovely time until you showed up," snarled another of the warriors.

Jurgen glared at Herya. "And as for you, Valkyrie, stand with us or face thea""

"Oh, shut up, Jurgen," Herya said. She shoved Zac into the bowl of the shield. "And just so you know, when I spilled that drink on you earlier? So not an accident."

Zac looked beyond the edge of the shield to the deep trench in the snow. It was already refreezing, the sides now smooth and slick like polished glass. The shield scraped across the flagstones as Herya heaved it over towards the hole in the wall. Zac finally understood her plan. He gripped the shield's edge as Herya shoved the makeshift sledge on to the polished ice.

"Hold tight!" she said, jumping in behind him.

"Yeah," he replied, as the front of the shield began to dip and the back rose up into the air. "I kind of worked that one out for myself."

There was a bellowed, "Stop them!" from the hole in the wall as the slow-witted Vikings realised what was going on. But there was no stopping them now. As gravity took hold and friction gave up, the shield began to hurtle headlong down the hill.

A blizzard hit Zac in the face. The icy winds tore at him, forcing him to screw up his eyes until they were almost closed. The snow swished past beneath the shield as it raced like a toboggan along the trench cut by Angelo and Odin.

"They're getting away!" said one of the Vikings as they watched the shield slice down the hillside.

"Not for long," said Jurgen. He crammed two thick fingers in his mouth and whistled. Eight winged shapes clambered from the shadows by the ceiling and plunged screeching from the rafters. "Right, then," said Jurgen as the Valkyries alighted around him. "Think they can ruin our party, do they?"

Zac ducked his head and gulped down a breath. The wind was impossibly cold. It snapped at his skin like a thousand biting insects, making his eyes water and his face go numb.

"I'm free. I don't believe it a" I'm free!" Herya said, but the whistling of the wind stole her words away.

"What?" Zac asked, straining his ears.

"Nothing," Herya said, raising her voice to be heard above the storm. "Uh-oh."

"Uh-oh? What do you mean, uh-oh?"

"We've got company," she said as eight winged figures swooped across the sky behind them.

Zac squinted ahead through the snowstorm. He could see the writhing shapes of Angelo and Odin, still locked in battle, still unaware of the drop into nothingness that lay ahead of them. The sound of each thunderous punch and kick rolled across Asgard. It was surely only a matter of time before the other gods emerged from their palaces to find out what all the racket was about. Zac tried not to think what would happen then.

"Go right!" Herya barked, snapping him back to the present.

"What? Why?"

"Stop asking questions and go right!"

Zac threw his weight sharply to one side. He heard a short, sharp scream, followed by a crunch. He risked a glance back and saw a Viking lying face down on the hard-packed snow, unmoving.

"What the Hella"" he began, before a cry of "Geronimo!" and a loud whumpf cut him off. Another Viking plopped into a soft snowdrift just off to the left of the trench.