Title: Any Sufficiently Advanced Technology...
Author: smrt1
Warnings: crossover, kid!fic, crack!fic
Timeline: Torchwood, sometime post 1.4 and before 1.10. Harry Potter, AU CoS.
Notes: Originally written for class (yes, I've got a class that I can do fanfiction for). Also, I don't own anything or anyone at all in this, so plz to not be suing, yes?

Chapter One: In Which Certain People in Cardiff Become Eleven Year Olds

None of them were quite sure how it happened, all they knew was that one minute, they were sitting around eating some Thai take-out (or, at least, that's what Ianto had said it was; Owen was of the opinion that it was actually Italian as made by three year olds using Play-Doh, and everyone had agreed that they weren't ordering from this place again), then there was a flash of light, and... they had shrunk. Not a lot in some of their cases (Tosh), and quite a bit more in other cases (Jack).

"Anyone feel like telling me why we're suddenly pre-teens?" That was probably Jack's voice, but it couldn't be Jack, Ianto thought, because it was coming from a kid who looked like he was maybe eight. If he stretched.

"What do you mean, 'pre-teens'? You're not nearly that old. You're barely out of nappies." That was definitely Owen.

Mini-Jack, or whoever he was, pouted in response. "I'll have you know that until I was thirteen, I was very small for my age!" It came from growing up in space, where the lack of natural resources made everyone incredibly small, but he wasn't going to tell them that. It would totally ruin his dark and mysterious persona.

This settled (not that anyone really believed Jack), they went back to the 'what just happened' problem. But alas, nobody knew how they'd all suddenly became children all over again. Or, more importantly, how to fix it.

Tosh and Ianto searched the inventory and archives for anything that might have caused the regression, while Owen performed multiple tests using blood samples from each of them, and Jack and Gwen sat around and kicked their heels for a while before deciding to play with Myfanwy (Owen was trying to figure out if this was a side-effect of the age regression, or just Jack and Gwen being themselves; Ianto's vote was on the latter).

A good five hours of work later, and... they had come up with nothing. Ianto had an idea of how to help them get back to normal, but it was sort of a last resort. Because he really didn't feel like telling the others that he was a wizard, even if he could Obliviate or retcon them after all this was over. And anyway, how likely was it that this was caused by something magical, as opposed to technological? That never happened.

They all worked through the night, but Owen couldn't find anything wrong at all with their blood compared to the samples they had given when they first began working at Torchwood. According to every piece of alien technology they'd ever salvaged, and the best human technology ever developed, they were exactly the same. Only younger. And, Owen found to his annoyance, the years of orthodontic work that had been done on his mouth during his teenage years was totally reversed.

Tosh found a few pieces in their collection that had less than full descriptions and might be responsible, but each was eventually ruled out through a lengthy and boring testing process that made Jack's eyes cross whenever he tried to pay attention. When it hit seven in the morning and they still had no clue to what happened (and Jack had given up on trying to keep his pants up and was just running around in a shirt that came to his knees), Ianto sighed and decided to pull out his trump card.

"I may," he told the others reluctantly, "have a way to get us back to normal."

"And you didn't tell us earlier because why?!" Owen snapped at him, nerves worn down by a combination of staying up all night and running every test known to mankind (and a number that weren't), and Jack refusing to let anyone have coffee, saying it would stunt their growth.

Ianto didn't answer, but instead shuffled over to the fireplace (ignoring the mutterings of, "Why do we have a fireplace in the Hub? Wasn't this an old train station? Who puts fireplaces in train stations?"). He opened an inconspicuous jar next to the fireplace, tossed a handful of powder into the fire ("Okay, how is the fireplace lit if we didn't even know there WAS one?!"), and called out, "Albus Dumbledore, Hogwarts."

Eyebrows were generally raised in amusement at the evident psychotic break Ianto was undergoing, but those eyebrows shot towards the roof when a face suddenly appeared in the fire. It was the face of an old man, with half-moon glasses and long white hair and beard. And a pointy hat. Everyone but Ianto stared at him in disbelief. (Well, really it was only Owen and Gwen; Jack just had a small smirk on his small face, and Tosh was sure there was a technological explanation – why, she could already come up with a number of them!)

"Mr. Jones, is that really you? Why, you look exactly the same as you did thirteen years ago!" the old man sounded astounded, but looked just slightly amused.

"Yes sir," Ianto said, kneeling in front of the fire, still ignoring the rest of the group. "You see, my colleagues and I were somehow turned into eleven year olds. We haven't been able to figure out a cause for it, and I was wondering if you might be able to help."

"Yes, yes, my dear boy! Step back from the fireplace, I'll come through and see what can be done."

And sure enough, a second after Ianto scrambled away from in front of it, the man stepped through the fire and into the Hub. Jack and Gwen immediately went for their guns, only to remember that they weren't actually wearing them (Gwen had managed to keep her pants on – a situation that Owen had many a snarky thing to say about – by tightening the belt to a ridiculous amount and rolling up the cuffs, but the weight of wearing a gun would pull them right back down).

"Nice dress," was Owen's only reaction. Tosh elbowed him, since she had actually been taught to respect her elders, and Ianto rolled his eyes.

The weird old guy in the dress has brandishing a stick, and when he muttered a few words it began to glow. He ran it over each of them and studied them carefully, frowning a little. He opened his mouth to say something, but Owen – ever snarky – interrupted. "Lemme guess, you have some good news and some bad news."

Dumbledore smiled, eyes twinkling. "Well, yes. The good news, as you put it, is that I know the spell that made you children again. The bad news is that it can't be reversed, it has to wear off." He paused. "And the worse news is that it takes a year to wear off." For someone delivering bad news, his eyes were twinkling a disturbing amount.

Reactions were varied. Ianto dropped his head, looking resigned – it would figure that the one time it was magic's fault, it would be something like this; Owen rolled his eyes and mouthed, 'Magic?' at Tosh, who elbowed him again; Gwen looked panicked; and Jack... looked amused. Again. Ianto glanced suspiciously between his boss and the headmaster, mentally noting that they seemed to have the exact same expression.

"I have some other news for you, as well," Dumbledore said after a moment. He'd been watching their reactions, and was pretty certain it was, indeed, news to them. "You two," he gestured at Owen and Jack, "are wizards, and the young ladies here are witches."

Jack and Ianto didn't react, but Owen snorted and Gwen and Tosh both looked highly skeptical.

What followed was the typical display of magic given to equally skeptical Muggleborns and their parents every year – around the same time, as well. Ianto reluctantly assisted, pulling his own wand out to the surprise of... well, no one, really, since the old guy had recognized him.

After having convinced them of magic (Owen was particularly stubborn about it, and had to actually be given Ianto's wand and perform a spell – bad as it was, given that it was a borrowed wand – before he began to believe), Dumbledore offered them all a place at Hogwarts. As Ianto pointed out, no one was going to let a group of primary schoolers into crime scenes to investigate Torchwood-related crimes, so they might as well go to Hogwarts and learn things that would be useful in their normal activities rather than just sit around and play with shiny objects and the pterodactyl.

Jack cheerfully accepted Dumbledore's offer, not seeming at all perturbed by both the news that magic existed, and that he was going to be stuck at eight – eleven, Ianto reminded himself – for a full year. But then, he was Jack. For all they knew, he could have planned it.

That was why, two days later (and a call to the Prime Minister informing her that they were magically eleven years old again and going off to study magic in Scotland, which she took surprisingly well), the five members of Torchwood 3 were standing in the alleyway behind a dingy pub. Ianto glanced around and carefully tapped a brick with his wand, not blinking as the doorway to Diagon Alley formed. Tosh was muttering under her breath possible scientific explanations, Gwen was staring open-mouthed, Jack was... smiling again, and Owen just decided to ignore everything and walked through the hole. "Well? Come on!" he snapped at the others, who hadn't moved.

Jack, of course, immediately took control, looking intently at the supplies list they'd each been given. "Okay, let's get fitted for robes first, then get potions supplies, then books and we'll finish with the wands." Everyone agreed with this strategy, and they followed Ianto to Madame Malkin's.

Things went far better than Ianto ever could have hoped – until, of course, they went to get their schoolbooks. Tosh's eyes lit up at the sight of all the books upon books upon books, and somehow managed to slip away from the group without anyone noticing. Owen found the section on magical medicine and healing techniques and was soon entirely lost, as was Gwen when she stumbled across Quidditch. They all seemed relatively harmless, wrapped up as they were, so Ianto kept his attention on Jack – who was, after all, the most likely to get into trouble. Didn't matter how much your world gets turned upside-down, you could always rely on Jack to piss somebody off.

Which was why Ianto was rather surprised that when a fight did start at the bookstore, Jack had nothing to do with it. They had been standing off to one side of an incredibly long line while Jack criticized the guy the line was for – a 'Gilderoy Lockhart'. "My hair," Jack whined, "is so much better than his!" He had just moved on to complaining that he had a better sense of style (post-Dumbledore, Ianto had shrunk all of their clothing down to a normal size, so Jack was dressed in his typical World War garb) and nobody ever lined up for him like they did for this guy, when a fistfight broke out between two adults nearby.

Ianto, his first time through Hogwarts, had been in the same year as the oldest Weasley child (different house, but same year). So it wasn't exactly a great intellectual achievement, figuring out who at least one of the duelers was.

"I've seen better fighting at nursery schools," Owen remarked over Ianto's shoulder, causing a miniature heart attack in the Welshman – er, boy. "Just because they've got magic is no excuse to fight like a baby." His tone was quite scathing.

And also just a bit too loud. "Hey!" shouted one of the younger redhead gathered around (with two non-redheads next to him, which was a bit of a shock).

Owen rolled his eyes. "Oh please. I bet Mr. Frilly up there-" he jerked his chin in the direction of Lockhart, "-could fight better than these two are doing." The blond boy nearby, who was likely supporting the other side of the fight, made a face that looked like agreement, but didn't speak.

"Professor Lockhart is a great duelist!" proclaimed the bushy brown-haired girl standing with the redheads. "Haven't you read his books?"

"Right, because nobody could ever lie in a book. That's why there's no such things as fiction." Owen's voice was dry and sarcastic, not that this was any change from its usual tone. He glowered at the girl while Ianto surreptitiously reviewed the information he'd been able to turn up on de-aging spells. There was much disagreement between experts in the field, but the one thing they had all agreed on was that victims of the spell would rather quickly be subjected to the emotional and rational states of their original younger selves. Owen appeared to be regressing faster than the rest of them.

"Oi, what's going on?" Gwen said, marching up with her hands, balled into fists, on her hips and glaring at the irate looking twelve year olds. She positioned herself directly in front of the guys with the look of a guard. Jack, Ianto noted, was doing his level best not to snicker uncontrollably.

Tosh had followed Gwen, a curious look on her face and her arms loaded with books. Ianto groaned at that. "Tosh, you don't need all of those," he tried to tell her, but she just gave him the widest-eyed look he had ever gotten, and he sighed and refocused on trying to keep his teammates from attacking a group of underage wizards. "We still have to get wands," he remarked calmly, going into what he had always privately thought of as butler-mode. He then eyed Owen and Gwen, undeniably the hot-heads of the group. "And I'm sure if we finish early, we could get ice cream. The wizarding world has far more flavors than you can imagine."

Neither of them were stupid, but Gwen allowed herself to be pulled away by the promise of ice cream, and Owen wasn't about to get into a fight without any back-up. Besides, it would take away from the hilarity of two full-grown adults brawling in the middle of a bookstore. So he shrugged and followed the rest of Torchwood to the front, where they paid for the books (all of them, since Ianto hadn't been able to talk Tosh out of more than two of the books).

Behind them, the fight stopped, and as they left the store, Ron Weasley muttered darkly to his the other, "I bet that arse is a Slytherin."

"No bet," Harry said, shooting his friend a smile.

Gwen turned out to be a special case, with the first wand she held reacting to her (in a positive way, not a blow-out-all-the-windows way). It was alder, unicorn hair, nine inches – great for wards and shield spells, Ollivander had said. Gwen had practically snuggled the wand after paying for it, and did start bouncing around the store while everyone else were trying wands.

Tosh was a little harder, but within the first ten minutes she had received a willow wand, core of phoenix feather, flexible and suited well for Divination work. Obviously thinking of the Mary incident, Tosh had grimaced and not looked quite as fond of her wand as she had previously.

Next was Jack, who took perhaps as long as Tosh to place, but who also managed to turn half the store into smoking ruins by the time he got the right wand. Hawthorn, thirteen inches, dragon heartstring, good for hexes.

Owen, though, they'd been there for at least a half hour. The pile of wands he'd tried and failed to do anything with had grown to the point where Jack, far shorter than the rest of them, was edging away in fear that the pile would fall on him and crush him. Ianto, fingering his own holly wand, wondered something... "Accio Owen's wand!" he whispered, and sure enough, a wand box from the back came zooming out. Ianto immediately took his hands out of his pockets and smiled innocently at the suspicious look Ollivander gave him.

Owen gave a similarly suspicious look at the box, but pulled out the wand. He flicked it, and a full rainbow of sparks came out the tip. "Ah, yes!" Ollivander said, clasping his hands, "Another hawthorn wand! Eleven inches, phoenix feather, perfect for charms."

Having decided that Ollivander was a completely crazy old coot, the Torchwood crew headed back to the Leaky Cauldron. Nobody had really felt like hanging around Cardiff until September 1st , and the wizarding world was a lot more accepting of a group of little kids running around without parental supervision for weeks on end. So they'd gotten two rooms at the Leaky Cauldron, above the pub, one for the girls and one for the guys (and, Jack had said, giving pointed looks at Owen and Gwen, they would be sticking with that sleeping arrangement).