It was quite late by the time they left Mr Evergreen’s house. This time, there were little carts that trundled them back up the long drive to the gate. “No need to prove they want to leave,” said Snape, when Harry commented on this. It was a very smooth ride, and Harry felt his eyes growing heavier.

The cart rolled to a stop, and the jostle of Snape getting out jerked Harry back into full consciousness. Marble gave a loud snort, as if warning him to be careful.

“Come along, Potter,” Snape said, and ushered him out through the tall gates. Moving a few steps forward, Snape held up his wand.

The Knight Bus had obviously been in the middle of a turn when summoned, as it appeared curving towards them on just two wheels. There was a horrifying moment when Harry thought it was going to tip over on them and crush them. He drew back against Snape’s still figure. Marble, his travelling box clutched tightly to Harry’s chest, reared up, his wings outspread as though trying to intimidate the monstrous purple vehicle.

Just when it appeared the bus was going to lose all balance and fall, there was a loud, metallic ping! from near the top of it, and it abruptly tilted the other way and landed with a thump on all four wheels. It juddered to a complete halt in front of them.

Harry found himself panting after holding his breath in anticipation of imminent death. Marble was agitatedly rustling his wings, snorting contemptuously. Apparently, he already didn’t much care for this mode of transport either. Harry couldn’t blame him.

“Welcome to the Knight Bus, emergency transport for stranded witches and wizards,” the conductor was saying, reading off a small card. Despite the fact it was the same conductor that had been there when Snape had tried to return him to Privet Drive, he didn’t appear to have learned his lines too well. “My name is Stan Shunpike,” the teenaged boy continued, “and I will be—” He raised his head, and came eye to tip with Snape’s wand. A strange gurgle escaped from his mouth, but no other words.

“We know who you are,” Snape sneered at him. He jabbed the wand forward, and the boy hurriedly backed up. “Come on, Po—” Even giving the wand a cross-eyed look, the conductor was obviously too interested for Snape’ peace of mind. “Podraig,” the professor corrected himself, with barely a hiccup.

Harry looked down at Marble. Podraig? he mouthed, but the Aethonian just shook his mane out and snorted.

Still puzzling over what the strange word meant, and why Snape had applied it to him, Harry followed his professor up the steps into the Knight Bus only to come to a halt as the interior met his eyes.

For instead of the armchairs the bus had had last time, now a row of beds stretched out. They all appeared to be four-poster beds, but without any curtains hanging around them. Strangely enough, they were all single four-poster beds, and were already swaying alarmingly from the bus’ wild halt. They all had different coloured bedding, none of which seemed to match any other piece. One bed was already occupied, the sleeping wizard in it snoring loudly. Harry wondered how on earth he managed to sleep through what was, essentially, a roller-coaster ride.

“Here, boy,” Snape called, and Harry darted down the aisle at the end of the beds to where the professor stood. He gestured for Harry to choose a bed. Dubiously, Harry poked at a bed with a pale green cotton blanket on it, before gingerly clambering onto it. Snape waved his wand, and Harry felt the Sticking Charm hit both him and Marble’s box.

“Ah, and where might we be taking the professor to this time?” Stan Shunpike asked, giving a smile that he no doubt thought was charming, but just made him look creepy.

“Spinner’s End,” Snape said, briskly, handing over the relevant coins, and sat himself down on the bed beside Harry’s.

“Spinner’s End,” said Stan, and then paused, as though expecting something else. When Snape said nothing, merely stared at him, Stan frowned slightly. “Right you are, sir,” he said, and made his way to the driver’s area, casting looks over his shoulder every so often. Harry was quite surprised he didn’t trip over one of the beds, since he was more concerned about what was behind him, rather than looking where he was going.

The Knight Bus took off with a jerk – apparently back to the corner it had been rounding before, as the entire vehicle suddenly slewed sideways. The bed Harry was sitting on abruptly felt like it was on wheels, and it rolled with the motion in a way that made Harry feel distinctly unpleasant. He grabbed hold of one of the upright columns, and swallowed hard.

Snape didn’t appear to be having any trouble, but when he could spare a glance, Marble was standing with all four legs braced, and his head low to the ground. Idly, Harry wondered if horses could get travel sickness.

“Where . . . exactly . . . are we?” Harry managed to get out. He’d tried looking out of the window, but it was now too dark outside to see. Then again, that may have been a blessing in disguise, since he wasn’t sure he wanted to see the route the bus was taking – or not taking.

“Essex,” said Stan, confidently, but then he frowned. “Or maybe Edinburgh.” There came a gargled murmur from the driver’s seat, and the conductor’s expression cleared. “Ah, Middleborough,” he proclaimed, beaming at them.

There was a sudden bang and lurch from the bus, and then the sound of water hitting the bus. At the same time, there came the faint, tinny sound of an alarm clock. Harry glanced upwards. He didn’t want to think of how loudly that alarm was ringing if he could hear it from a floor down . . . or even two, if it had been on the top floor.

Stan disappeared up the stairs, just as the bus came to a halt as abruptly as if it had smashed into a brick wall. All the beds on the ground floor – and presumably the other floors, too – smashed together at the front end of the bus. Despite the Sticking Charm, Harry grabbed frantically for both the bed and Marble’s box as the entire bed swung wildly. He vaguely envied Snape, who sat there as calmly as if he were sitting in his own non-moving armchair.

“Loch Ness!” Stan’s voice floated back down to them. “Loch Ness! Who’s for Loch Ness?”

“Loch Ness?” Harry tried to peer out of the window, but could still see nothing but the reflected interior of the bus. “We’re actually at Loch Ness? In Scotland?”

Snape made a vague humming sound of agreement. “From the sound of it,” he said, “we’ve just travelled straight over the Loch.”

Harry raised his eyebrows. That’s what the sound of water had been? Then his eyebrows drew together in a frown. “The bus can travel over water, sir?” he asked.

“It’s a magical bus,” Snape pointed out, raising an eyebrow of his own at Harry. “It can travel almost anywhere you want the bus to take you.”

Harry tried hard, but couldn’t entirely suppress the blush that crept up his face. He supposed he should have thought of that, but he was still getting used to the fact that wizards even had a bus system at all.

Voices came from upstairs, and two wizards tip-toed down the stairs, Stan hurrying behind them, trying his best to get in front. The foremost wizard staggered to the door and lurched out before Stan could grab him. There was a brief whoop, and an almighty splash.

“Mind the step,” Stan said to the other wizard, forcefully. He spun the wizard around, and pointed at a door that Harry hadn’t noticed before, directly opposite the one they’d got in by. “That’s the land side.”

From outside came a bellowing, yet somehow musical, roar that sounded as though it were underwater. Something slapped against the outside of the bus, which rocked alarmingly, and something went yodelling overhead.

“Thanks, Nessie!” Stan yelled out of the door the unfortunate wizard had fallen through, and half-pushed the second wizard out of the land side door.

Harry gaped at Stan, then tried his hardest to see out of the window, before turning to Snape. “Nessie?” he asked, disbelievingly. “The Loch Ness Monster is real?!”

“Of course it’s real,” Snape said, sounding briefly puzzled. “Even the Muggles have pictures of it.”

“I thought they were just hoaxes,” said Harry, turning back to the window. He jumped when the underside of what looked like a flipper slapped against the glass, before sliding off again.

“Nah, Nessie just don’t like being photographed that often,” Stan said from behind him, and reached out to slap twice at the wall. “Thanks, Ness! Take ‘er away, Ern!”

“Yeah, take ‘er away, Ern!” chortled the shrunken head hanging beside the driver.

Harry gulped and made a grab for the bedcovers and Marble’s box, as the bus leapt away as though rocket-propelled, and all the beds slid down towards the back of the bus.

By the time they stumbled off the Knight Bus in Spinner’s End, after zig-zagging up and down the country for half an hour, Potter had turned a nasty shade of white, and the animated Aethonian was leaning heavily against a corner of its box, as though the two walls were the only thing keeping it upright.

Severus had to admit, the trip had been a tad wilder than it normally was. No doubt the vision spells on the shrunken head that linked to the driver’s thick coke-bottle eyeglasses needed refreshing again. Either that or the thing had been asleep for part of the journey.

“Come along, Potter,” he said, turning to unlock the wards on his front door. “I think it’s past time you were in bed.”

The boy looked as though he wanted to protest, but even as the thought crossed his mind, a yawn took him by surprise.

Severus carefully concealed a smirk as he ushered the boy into the house in front of him, ensuring that he set the wards again once they were safely inside. Turning back again, he studied the living room. “I believe that Marble will be spending the night in your room, Potter,” he decided, finally. He’d heard a lot of stories about how long it took animated figurines to settle in, and he had no wish to be disturbed by the Aethonian flapping back and forth and posturing at the non-animated figures all night.

Potter had sat down on the edge of his armchair, his school books still lying on the seat from when Severus had discovered Bertie’s letter and hustled him out. His head was down, although Severus couldn’t tell if that was because the boy was studying Marble or if he was falling asleep where he sat. Or, of course, he could be giving thanks for being back on steady ground, Severus thought, a corner of his mouth curling upwards before he caught himself.

Drawing his wand, Severus leaned in and tapped it thrice on the top of Marble’s travelling box, preparing the charms to reverse themselves. It was hard to ignore Potter’s violent flinch as his arm suddenly appeared in the boy’s line of sight, but when Potter flushed and darted a quick upward glance at him, Severus pretended that he hadn’t noticed. That was a conversation for another day when it wasn’t so late.

“Place the box upon the desk in your room,” he instructed. “Marble may be very active at first; try to ignore him if at all possible. He needs to learn that he won’t be pandered to.”

The Aethonian let out an indignant snort and shook his head, his mane flopping over his neck.

Potter gave a weak smile, then a slightly firmer one to the Aethonian. “He won’t bother me,” he said. He rose to his feet, clutched the box tightly to his chest with one hand and scrabbled to scoop up his school books with the other hand. “What about food and . . . stuff?” he asked, hesitantly. Marble tilted his head and peered up at the boy.

Severus shook his head and moved towards the bookcase hiding the stairway. “He may be animated, but he’s still only a figurine,” he pointed out. “His innards are still resin. What the entire figure is made of,” he added, sensing rather than seeing Potter’s mouth open on another question. “It’s a type of modelling material, made of hardened tree sap.” It was a bit more complicated than that, but he wasn’t sure Potter would have understood, even if the boy wasn’t almost asleep on his feet.

Opening the bookcase, he gestured for Potter to go up. “Go to bed, Potter,” he said.

Potter had barely set foot on the first stair before he suddenly paused, and then turned and scurried back into the living room, a flush creeping over his cheekbones, setting Marble’s box onto the seat of the armchair as he passed. Realising what was wrong, Severus stifled a chuckle as Potter dashed outside towards the outhouse.

When he returned some five minutes later, he scooped up Marble’s box and headed for the stairs again. “Good night, sir,” he murmured. Marble snorted and bobbed his head.

“Good night, Potter,” Severus responded, and closed the bookcase door behind the boy.

Harry placed the travelling box on the small desk and sat down on the bed. The box slowly turned opaque, almost as if it were filling with fog. Once he could no longer see inside, the box abruptly sprang open, almost like a flower unfurling its petals, until it was lying flat on the desk.

It reminded Harry of primary school, when they’d been making 3D shapes. He’d figured out how to do it fairly quickly, but Dudley hadn’t seemed to get the hang of it at all, so Harry had done it once, just to prove to himself that he could, and had then spent the rest of the lesson putting it together in every way but the correct one. After his fourth ‘attempt’, the teacher had left him alone in disgust at his ineptitude.

Now, the animated Aethonian stalked off what had been his box and stood at the edge of the desk, his head up as he examined his new kingdom, his wings mantled up and open to make himself look bigger. Finally, with a long rolling snort, Marble backed up a couple of paces, and then launched himself off the desk, spiralling upwards to circle the light fixture.

Harry shifted to lie on his back under the covers, idly watching as Marble soared past the other figurines, obviously showing off to them. It was hypnotic, and it wasn’t long before his eyelids were drooping shut.