London, October 13th, 1910

The church was cold and empty. Their footsteps echoed in the cavernous space as Rory, Amy, and Arven hastily took cover inside.

"Help me with this," Arven requested, attempting to close the heavy oak doors with his remaining arm. Rory ran to his aid, pushing them shut and sliding the deadbolts into place. Within seconds, the doors were buckling violently in their housing as the three Squall threw themselves against the other side, trying to force their way in.

"Great. Now we're trapped again," Amy said despondently.

Rory looked around, trying to get his bearings. The building was ancient and somber, solidly built, thick stone walls inset with rows of stained-glass windows. The sunlight shining through them cast colorful patterns over the rough wooden furniture below.

"They're not going to give up," Arven argued, and as if to underline his point, there was a tremendous bang from above as the creatures tried to batter their way in through the roof. Rory saw dark shadows flitting past the windows.

"There's more of them," he reported. "They've found us."

"It won't take them long to work out they can break in through the windows," Amy pointed out. "We need to think of a plan."

"We can barricade the doors with some of those pews," Rory suggested, pointing at the ranks of wooden benches lined up behind them.

"They'll still be able to get in through the windows," Arven reminded him. "Amy's right. We don't have very long."

Amy crossed to the altar at the far end of the hall. "Do you think there's another way out?" she called, her voice echoing around them.

Rory shrugged. "Probably. But that won't do us much good. They'll be waiting outside."

"No, I don't mean a back door. These old churches always have hidden nooks and crannies, secret passageways and stuff. You know the sort of thing: dark, dingy tunnels, dead people."

"I think you've been watching too many horror films," Rory teased. "But we're running out of options." He went to join Amy. Behind him, the Squall were frantically scratching at the doors with their talons. He could hear hordes of them chittering and squawking outside.

Maybe it was just Rory's imagination (or, the nurse part of him had to admit, lingering PTSD), but the sounds were far too reminiscent of the Headless Monks' chanting as they prepared to attack him, his wife and baby, and their small, makeshift army on Demons Run.

His jaw clenched, and his fingers suddenly itched for a sword. He had to keep Amy safe. "Okay," he said determinedly. "There's got to be something around here. Some other way out. Arven, can you keep an eye on those Squall while Amy and I take a look around?"

The AI nodded and turned to face the doors. Rory turned to tell Amy they should split up, but found she'd already gone. Sighing, he set out for her.

Behind the altar and pulpit was a series of smaller rooms – private rooms, Rory assumed – for the vicar. They were sparsely furnished. One of them contained only a beaten old table and a few chairs, along with a basic stove and tea-making equipment. Another held a desk and a number of bookcases, the shelves lined with row upon row of musty leather-bound tomes. The doors were solid enough, and if it came to it they'd be able to retreat into one of the rooms, effectively shutting themselves off from the invading Squall, but Rory knew they wouldn't be able to hold out for long.

"Over here!" he heard Amy cry a moment later. He ducked out of the study, picking his way along the narrow stone passageway. He found her standing between two large marble tombs, each of them bearing the solemn-faced effigy of the dead person it contained. She had a triumphant smile on her face.

"See! I told you! A secret passageway!" She stepped to one side, indicating a small doorway behind her. The door was hanging ajar, and Rory saw it opened onto a flight of worn stone steps. He inched forward and peered into the inky darkness below.

His protective determination suddenly faltered. "We can't go down there," he protested. "It could be anything. A dungeon. A tomb. A dead end."

"Well, it's not like we have any better options," Amy said pointedly.

Just then, there was a cry from the other end of the church, and their eyes met in concern. "Arven!" Rory cried, turning around and starting back down the passageway. He stopped when he heard Arven's footsteps thundering against the flagstones, heading in their direction.

A second later, the artificial man was sliding to a stop before him. "They're here!" he said urgently. "They're inside!" Sure enough, Rory could hear the Squall bashing their way in through the priceless windows.

"Secret tunnel it is!" Amy declared, reaching through the doorway and yanking something free from a bracket on the wall. It was a wooden torch – an actual, traditional torch – of the sort used to ward off monsters in those same horror films that Rory had joked about with Amy.

"Here, hand me those matches," Amy ordered, pointing to a small table covered in altar candles. Rory reached over and retrieved the matchbook from where it lay amongst the white pillars of wax. He pulled a match free, struck it, and put the flame to the proffered torch. It went up with a sudden whoosh and, before he knew it, the three of them were descending the steps into the darkness, Amy leading the way, the torch held high above her head.

Rory pushed the door shut behind them. "No one's been down here for years," he said, dismayed, as he fought to brush the cobwebs away from his face. They were in some sort of catacomb, a roughly hewn tunnel that was only just high enough for Rory to be able to stand at his full height. Arven, on the other hand, had to stoop to be able to maneuver in the confined space.

Innumerable alcoves had been carved into the walls, each one occupied by the remnants of the long dead. Some of them bore wooden coffins – or what remained of them – while in others there were simply heaps of dusty bones, wrapped in the occasional rag. The hollow sockets of the skulls seemed to stare at them as they crept along, winding their way further beneath the ancient building.

"These tunnels must go right under the graveyard," Amy figured, using the torch to singe away a particularly dense cluster of spider webs blocking their route. It was an eerie thought to consider they were entirely surrounded by the dead, both in the walls and high above them in the soft ground of the graveyard. Rory suppressed a shudder.

They pressed on like this for some time, mostly in silence, each of them expecting to hear the sounds of the pursuing Squall in the tunnel behind them at any moment. Amy led them along the narrow tunnel as it snaked further and further beneath the city, glancing back every few minutes to check that Rory hadn't fallen behind.

Presently, after what seemed like hours of trudging through the creepy passageway, Rory became aware of the sound of running water up ahead.

"Urgh!" Amy cried in disgust. "What's that smell?"

"Human waste," Arven replied in his usual monotone. "I think we must be nearing the sewers."

"Sewers?" Amy echoed. "Perhaps we should turn back?"

Rory covered his nose and mouth with his cupped hands in an effort to stifle the acrid stench. "No," he called. "No, there'll be a way out through the sewers. If these tunnels meet up with them, we'll be able to find a manhole to the street above. There's nothing but Squall back there in the church." They continued on, slowly growing used to the disgusting smell.

Sure enough, the tunnel soon came to a T-junction that opened out into a dark, brick-built sewer. The walls curved up around them, and filthy water sluiced along in a wide channel, carrying with it all manner of disgusting waste. Rory tried not to look at it.

The writhing forms of rodents scampered out of their way as they edged cautiously along the walkway. "Rats!" Amy bemoaned, with barely concealed horror. "God, I hate rats!" She waved the torch at the sea of them around her boots, and they squealed and shot away, splashing into the water.

"There's a ladder up ahead," Arven said, pointing to a spot a little further along the tunnel. Rory could just make it out in the semi-darkness, an iron ladder leading up to a manhole high above.

"Come on!" Rory called, urging them forward. "We'll be out of here in a few minutes." He took the torch from Amy and squeezed past her, leading them on with renewed vigor.

"Right, you first, Arven," he said as they came to the foot of the ladder a few moments later. The AI mounted the first rung and began the steady climb to the surface, bracing himself with his legs as he pulled himself up with his one remaining arm. "Now you, Amy." He watched until she was safely halfway up the ladder. Then, ditching the torch on the walkway, he followed behind the others.

When he finally got to the top of the ladder, Rory found that Arven had already shifted the cover to one side and was hauling Amy out into the street. Rory pulled himself up and out with a loud groan of exertion, and Amy helped him to his feet. He dusted himself down, blinking into the bright sunlight. A small crowd of people were milling around, staring at the three of them in astonishment as Arven slid the manhole cover back into place with a loud CLANG.

"Erm, hello," Rory said, offering them a little wave. "Sewer inspection."

"Yes, and everything's fine," Amy added, as if that was the end of the matter. "Ten out of ten." She grabbed Rory's arm. "Come on!" she said, urgently, and together the three of them, looking somewhat incongruous in their modern clothes, set off at a run, hoping to put as much distance between themselves and the Squall as possible.

~The Pros and Cons of Silence~

Three days.

Three days they'd been on the run, moving from location to location, each time hoping they'd happened upon a place where the Squall wouldn't be able to find them, each time being forced to move on when they did.

They'd been constantly on the move, resting for only a few hours at a time, moving around the city, living hand to mouth. They'd managed to purloin some clothes from a washing line in a deserted garden, getting a long black coat to cover Amy's short skirt, which had already drawn rather too much attention as they'd hurtled through the streets, and a shirt and cap for Arven, the latter of which they'd pulled down low over his face, making it easier for him to hide what was left of his damaged flesh.

They'd eaten only scraps of stolen food, or whatever they'd been able to beg from the scant few people who'd helped them. Arven, of course, needed neither food nor sleep and had proved a constant companion, remaining watchful and alert, keeping an eye on Rory and Amy while they slept.

Wherever they went, however, whatever they tried to do, they seemed unable to shake the constant hounding of the Squall. It was as if the aliens were somehow drawn to them, as if the creatures had picked up their scent and were doggedly refusing to let it go.

Rory suspected there was more to the creature's persistence than the simple impulse to hunt, of course, but he had no way of telling, and no real time to consider it. They hadn't been able to remain in one place for long enough. At one point, they'd taken shelter in a house in Kensington – a huge, well-appointed townhouse that appeared to be empty – only to find the still-warm corpse of a burglar laid out on the kitchen floor, surrounded by the scattered spoils of his trade. He'd bled profusely from his eyes, and at the sound of movement from upstairs they had fled again, realizing the Squall were already there, waiting for them. They'd spent the night beneath a railway bridge instead, huddled against the cold, wishing they'd been able to find somewhere warm and dry.

The previous day – October 16th – they'd waited with bated breath, waited for the Doctor and Alex to come storming out of the misty London morning to find them. Waited for the distant, elephantine roar of the TARDIS's engines. In the end, however, neither had come. The Doctor and Alex were somewhere in London, but the likelihood was that they didn't even have the slightest notion that Amy and Rory were there too.

They'd discussed going back to the scene of the crash, to see if they might find the couple poking around in the remnants of the time ship, but the presence of the Squall made that impossible. They knew they'd never even get near the ship, what with the sheer number of creatures in the vicinity.

They'd seen the newspapers too, of course, and were aware of the reign of terror under which the Squall held the city. There had been so many deaths, so many victims. The Squall were all over London now, picking their victims indiscriminately, plucking them openly from the streets. They loitered in the mouths of dark alleyways, hid around corners or swept down on people from the rooftops, gliding on their translucent wings. The evidence was there before everyone's eyes, but the police seemed entirely unable to acknowledge it, attributing the deaths to the work of an imaginary serial killer.

Rory had considered going to them, showing them the evidence himself, but he knew he'd simply be branded a madman and thrown in a cell, or worse, in a sanatorium. That would be no use to anyone, least of all Amy, Alex, and the Doctor.

Sighing, Rory peeled open his eyes.

Day was breaking. The sunlight slanting in through the window picked out the dust motes ebbing on the stirring currents. He watched them dance for a moment, transfixed.

Amy was still dozing on the pile of woolen blankets beside him, her hair like a spill of bright red ink on the makeshift pillow. Rory decided to let her sleep for a little while longer. He knew that she didn't really need protecting – if anyone could look after themselves, Amy Pond could – but it didn't prevent him from trying. It didn't change anything. He was her husband, and he had a job to do. Keeping her safe was his first priority.

The house they were in had clearly been abandoned for some months, if not longer. It was in a grave state of disrepair. It stank of mildew and damp, and the ceilings had collapsed in a number of places, opening up ragged holes that allowed them to see through to the floor above. They'd decided to remain downstairs for the duration of their brief stay, both to make it easier if they needed to get out in a hurry and to avoid any of them accidentally falling through the rotten floor from above.

They'd found the place almost by accident while trying to lose themselves in the slums of the Whitechapel district, hoping the sheer volume of people, coupled with the stench of the place, would help to throw the Squall off their scent. Rory had been appalled by the things they had seen while wandering the streets, the sheer poverty on display at every turn. The people there lived in absolute squalor, eking out a miserable existence with little or no prospects of ever finding a way out.

It was like something he might expect to see in the Dark Ages. But this – this was the 20th century. Surely there was no need for people to live like that in 1910.

Whatever the case, he'd been grateful for the empty house they'd discovered here, boarded up down a narrow lane. His survival instincts had kicked in, and together he and Arven had affected a makeshift entrance through a back window. They'd holed up in there for the night, wrapping up against the cold in whatever rags they could find. Now, it was nearly time to move on again. He wondered if today they might find the Doctor and Alex. Or rather, if the Doctor and Alex might find them.

He felt Amy stirring beside him. She blinked up at him with sleepy eyes. "Oh, it's not time to get up already, is it? It's so cold, and I'm so warm in here."

"I'm afraid so," Rory said. "We've got to get moving before the Squall find us. And besides, today's the seventeenth of October." He glanced over at Arven pointedly.

"Oh," Amy breathed, her mood suddenly changing. She sat up, propping herself on one elbow. They both knew what that meant. The AI they'd seen dredged from the Thames, a thousand years in the future, had been just like Arven. That one had also been missing an arm. It had been in the water for over a thousand years, and it had fallen into the water – the Doctor had said – on October 17th, 1910.

It was only a matter of time before Arven found himself in the river. It was practically inevitable, and it was going to happen today.

"I can hardly look at him," Rory confided, in hushed tones. "I didn't think he'd be like this, so much like a . . . person. I thought he would be just a robot, a tool created for a specific role."

"I know," Amy agreed, putting her hand on his arm. "But all we can do is try to prevent it from happening." She sighed. "I wish the Doctor and Alex would hurry up."

"I've been thinking about that. Do you remember in the future, on the embankment, when the Doctor spoke to the AI?"

"Of course."

"Well, it clearly knew him. It recognized him. And that means that at some point today, before he has his . . . accident, Arven is going to meet the Doctor. And if he meets the Doctor, Alex shouldn't be too far away."

Amy's eyes widened as the implications of his words struck home. Her face split into a wide grin. "Oh, you're not just a pretty face, are you?" she quipped, leaning forward to kiss him brightly on the cheek.

"Now all we have to do is stay alive long enough to find them," Rory said dryly.

"Oh, go on, spoil the moment," Amy chided, but she was smiling.

"Right. Time to get up." Rory heaved himself up and crossed to where Arven was standing, sentry-like, by the window. "Morning," he greeted. His mouth felt dry as he stood beside the proud figure of the AI. He didn't know what else to say to it, couldn't find any words that wouldn't sound hollow, knowing what he knew about the machine's impending demise.

Arven seemed to sense his discomfort. "I do not belong here," he said, keeping his gaze fixed on the street beyond the grimy window. People were already milling around out there, going about their morning business.

"None of us belong here, Arven," Rory said quietly. "But we have to stop the Squall. We have to find the Doctor and Alex and work out how to prevent them from sucking the planet dry, from killing any more people."

Arven turned his scarred face from the window to look at Rory. The ribbons of torn flesh still hung across his left cheek like trailing fingers. "I admire you, Rory Williams. I admire your resolve, your dedication. You remind me very much of Professor Gradius."

Rory swallowed, unsure how to respond. "Um, thanks."

He turned, grateful for the interruption, at the sound of a boot scuffing the bare floorboards behind him. Amy stood watching them both with an amused expression on her face, her hands on her hips. "Okay, boys," she said, full of gusto. "It's a brand-new day, and we're going to find the Doctor and Alex. Time to get moving!"

~The Pros and Cons of Silence~

When the Squall found them again, they were down by the river.

Rory had suggested they head to the waterfront, at least in part because it was where he expected the day's events to transpire, unless things somehow played out very differently to how he imagined they would.

The Doctor and Alex knew that the AI would end up in the river at some point that day too, so it seemed a reasonable assumption that they might come looking for them there. So, Rory had led them to what he thought was roughly the same location at which they'd first arrived in London over a thousand years in the future. It was presently a nondescript spot on the embankment overlooking the Houses of Parliament. All had been quiet when they'd arrived, save for the pigeons that pecked incessantly at his boots and the squawking gulls that wheeled beneath a canopy of dirty gray, high above their heads.

Amy had clearly recognized where they were, but she'd remained steadfastly silent on the subject of Arven. To Rory, this was a clear indicator that she suspected what was going to happen, but wasn't yet prepared to give voice to her thoughts.

Nevertheless, he felt somewhat guilty for hastening Arven on towards what would most likely prove to be the last few hours of his existence. Whether he was a machine or not, whether he actually experienced pain or anguish, he was still a person. Standing there on the embankment, looking out over the dark, glassy water, Rory had resolved to do whatever he could to save the AI, to alter the future, to prevent those things from coming to pass. Life wasn't predetermined. He knew that. Things could change. He'd seen the Doctor do it any number of times, plucking people out of their own timelines, saving people's lives, altering the course of events. Perhaps, then, there was hope for Arven?

Perhaps.

Now, however, Rory was feeling a little less confident, as he backed up against the railing, clutching Amy's hand in his fist. Moments earlier, a flock of Squall had descended in a gray flurry, swooping down on them from above. There were at least ten of them in the pack, and they didn't look as if they were about to take no for an answer.

Rory knew he should have been more prepared, should have been watching the skies, but the truth was that he was simply exhausted. Three days with hardly any food or sleep, remaining constantly on the run, had taken their toll. And now, it seemed, there was nowhere left for them to run. The Squall closed in on them, encircling them, hemming them in.

"You. Do. Not. Belong. . ." the Squall hissed in their broken, fragmented English. "You. Taste. . . Different. . . The. Hive. Shall. Absorb. Your. Minds. . . The. Hive. Shall. Feast."

Arven stepped forward, taking in each and every one of the aliens with a sweep of his head. "No," he proclaimed. "This ends here."

The Squall laughed, and it was one of the most hideous sounds that Rory had ever heard. "The. Artificial. Man. Is. Of. No. Consequence. . . The. Hive. Shall. Feast."

Was this it, then? Was this when Arven ended up in the river?

Rory was filled with a sudden sense of panic. He hadn't considered that he and Amy might end up the same way, dropped over the riverbank, their minds consumed by psychic parasites. Presently, it was looking like a distinct possibility.

Rory glanced at Amy, expecting one of her usual quips, but instead she simply grabbed hold of the back of his head, pulled him closer, and planted a whopping great kiss on his lips.

"You too," he said, turning back to the aliens.

There was nothing left to do. They were trapped, and the circle of Squall was closing in.

~The Pros and Cons of Silence~

London, October 17th, 1910

"See! Trouble. I told you. Always in trouble."

The Doctor and Alex, both grinning inanely, charged towards the gathering circle of Squall.

"Amy! Rory!" Alex yelled at the top of her lungs while at the same time, the Doctor bellowed, "Ponds! What do you think you're doing?"

"Doctor! Alex!" A woman's voice floated over the chittering of the alien beasts. "Over here!" She sounded triumphant and more than a little relieved to hear the couple's voices. She leapt up and down on the spot, waving her arms in the air above her head.

Angelchrist hurried along behind the Doctor and Miss Locke, keeping pace as best he could. It seemed odd to him that, after spending so much time running away from the alien creatures, the couple was now intent on running towards them. Such was the way of this bizarre, impossible man and woman; both able, it seemed, to change their minds on a whim, to see at least three steps ahead of their opponents, and take the necessary measures.

As they drew closer, Angelchrist was able to make out three people at the heart of the trouble – a pretty young woman with bright red hair, a thin young man in a checked shirt, and a tall, pale-skinned man wearing a black coat and cap. There were at least ten of the creatures encircling them, and they were backed up against the railing with nowhere to run. The Squall were closing in, clearly intent on devouring their minds.

The Doctor and Alex, of course, had very different thoughts on the matter. They skidded to a halt a couple of meters from the creatures. The Doctor yanked his sonic screwdriver from his trouser pocket and jammed it into the receptacle at the base of his amplification device, which he clutched in his other hand. He poised his thumb over the button, ready to trigger the contraption.

"Oi! You lot!" he called.

"You've had your warning!" Alex snapped. She pulled her sonic necklace out from beneath her shirt and raised the charm threateningly. Her eyes narrowed at the creatures, the copper irises turning dark and stormy. "Now beat it!"

"Go on! Get out of here!" the Doctor affirmed. He and Alex glared daggers at the Squall, who turned as one to regard them, their glassy eyes shining in the morning sun.

"Leave our friends alone." The couple spoke in perfect sync, their firm, forbidding tones sending chills down everyone's backs.

Everyone, that is, except the Squall. "The. Hive. Knows. You. Doctor. Alex. . ." they replied. "The. Squall. Have. Tasted. Your. Thoughts. Doctor. . . The. Hive. Got. A. Glimpse. Of. Your. Ally's. Mind. . . The. Hive. Hungers. For. Your. Minds."

The Doctor's jaw, already clenched, tightened even further at the mention of Alex. His fingers itched to tug her behind him, out of the Squall's sight. But with both hands occupied with the amplification device, that wasn't an option. Instead, his features darkened. His emerald eyes, normally glittering with enthusiasm and intelligence, were now stern and unforgiving, expressing a malevolence human eyes could never hope to reach.

It was the Oncoming Storm in all his great, terrifying fury. There was nothing anyone, not even Alex, could do to calm him down. The Squall had damned themselves with their actions, and they were about to face the consequences of angering and threatening the last of the Time Lords and his Ally.

"Ah," he said now, slowly and acerbically, "you see, that's where you've got it wrong. That's where you've got it very, very wrong. Because if you knew us, if the hive truly understood what Alex and I are about, it would know that we will never let it succeed, that we will do absolutely everything to prevent it from consuming this planet. It would know that we never give in, and that it should be very, very scared."

"It would know," Alex continued softly, eyeing the Squall contemptuously, "that it should have left when it had the chance."

The Squall cocked their heads to one side in a display of eerie symbolism, regarding the Doctor and Alex as though weighing their words. "The. Hive. Shall. Enjoy. Consuming. Your. Minds. Doctor. Alex. . . You. Are. Worthy. Enemies. Of. The. Squall. . ."

"Wrong answer!" Amy cried as the hungry pack of Squall turned away from her and launched themselves toward the Doctor and Alex, their talons glistening.

Calmly, the Doctor held his sonic screwdriver aloft. Alex aimed her sonic necklace out in front of her, stretching the thin metal chain as far as it could go while still being wrapped around her neck.

When they spoke, it was once again in sync, the words uttered in eerily calm tones. "We warned you."

And then they activated their sonics.

The results were instantaneous. The Squall dropped immediately to the ground like so many dead weights, screaming and writhing in agony. They clutched their heads, some of them even using their own talons to burrow into their flesh as if trying to physically wrench the noise out of their heads.

Amy looked at the Doctor and Alex, a wide-eyed expression on her face. Behind her, the man in the checked shirt – Rory, Angelchrist presumed – didn't seem nearly as surprised, merely regarding the couple with an expression that seemed to suggest equal measures of surprise at their actions, but also acceptance of them.

The Doctor released the trigger. Alex cut off her necklace's buzzing. All around them, the grey-skinned creatures were sprawled on the ground, groaning and shaking their heads in confusion.

"Go," the Doctor commanded, his voice low and dark. "Before we activate them again."

The nearest Squall looked up at them and hissed, its fangs gleaming. Dark red blood was trickling from its ears.

"GO!" the Doctor and Alex bellowed, and the creatures scattered, scrabbling over the paving stones and scampering away into the hazy morning. Seconds later, there was no sign that they had ever been there at all.

The Doctor and Alex met Amy's gaze. The Doctor offered her a playful smile as he said, "It won't keep them busy for long."

Amy's face split into the widest of grins and she ran at him and Alex, wrapping her arms around their shoulders and squeezing them tight. While Alex eagerly reciprocated the hug, the Doctor looked decidedly uncomfortable, and, with both hands full, simply stood there and allowed himself to be squeezed, a baffled expression on his face.

A moment later, Amy released them, stepped back, and folded her arms crossly over her chest, although Angelchrist could tell it was mock fury. "Three days! Three days we've had to hang around waiting for you two to show up. Do you know how desperately I need a shower?" She punched the Doctor gently on the arm. "Three days!"

Alex gaped at her. "You've been here for three days?!"

The Doctor glanced from Amy to Rory, and then back to Amy again. He gave her an apologetic look. "I thought I left the two of you safely in the 28th century?"

"Well, you left us in the 28th century," Rory said dryly. "I'm not sure if safely is exactly the adjective I'd use to describe it."

Angelchrist raised an eyebrow. The 28th century!

"The Squall," Amy clarified. "The Squall were there, too. We found Professor Gradius, but we were too late. They'd already killed her. We used her time ship to get away, to come back to 1910 to find you. Only, we overshot by a few days."

"I'm sorry," the Doctor said solemnly. "I'm sorry I put you through that. Both of you."

They stood in silence for a moment.

"Still," the Doctor said, a little sheepishly, "it must have been a little bit exciting, wasn't it? Traveling in an experimental time ship. Breaking new ground. You were probably some of the first humans in history to take part in an incredibly, profoundly dangerous time experiment. I mean, really, anything could have happened." He prodded Amy inquisitively on the shoulder, then pinched her cheek between his finger and thumb as if checking she was actually real. Amy slapped his hand away and rubbed at her face. "So? What was it like?"

Rory sighed. "Fine. Good. Right up until the crash landing."

"Yeah, we saw that," Alex said. "Still," she added, giving him a conspiratorial grin as she nodded towards the Doctor, "you should be used to crash landings what with this one's driving."

"Oi!" the Doctor cried, giving her a wounded look.

Feeling ever so slightly discomfited, as if he were intruding on a private conversation, Angelchrist gave a polite cough into his fist in an effort to remind the Doctor and Miss Locke of his presence.

"Oh!" Alex cried, her expression immediately becoming abashed. "Sorry, professor!" Smiling apologetically, she waved him forward. "Professor Angelchrist, Amy Pond and Rory Williams. Amy and Rory, Professor Angelchrist."

"Good," the Doctor nodded once the introductions were over and pleasantries exchanged. "So, we all know each-other. Now we can get on with stopping the Squall." He grabbed Alex's hand and turned as if to set off.

Alex, however, dug in her heels. "Wait a second, Doc. You're forgetting someone." She nodded to the unusually tall man who was standing off to one side, quietly watching the retreating Squall.

"I am?" the Doctor said, only for it to come to him a second later. "Oh! Of course I am!"

Amy grinned, beckoning to the pale-skinned figure. He stepped forward so that the Doctor, Alex, and Angelchrist could get a better look at him. "This is Arven," Amy introduced. "He's a friend."

Angelchrist regarded the unusual figure. At first, his brain failed to recognize the ragged strips of flesh hanging loose from the man's face, or the dull, exposed metal of his cheekbone beneath. And then it hit him, and he almost staggered backward in surprise.

The man wasn't human.

"Ah, hello, Arven," Angelchrist greeted, extending his hand.

The artificial man took it and shook it firmly. His hand felt rubbery and cold. "Likewise, Professor Angelchrist."

The Doctor was grinning like a lunatic. "Arven?" he said, with a knowing glance at Amy.

"My official designation is RVN-73," Arven elaborated.

Angelchrist stepped out of the way to allow the Doctor through.

"Oh, look at you!" the Doctor enthused, releasing Alex's hand and giving Arven an appraising look. "You're beautiful. Well, not as beautiful as Ally here, but close." Beside him, Alex blushed scarlet, but that didn't stop a small, pleased smile from crossing her lips. It faded, however, as she joined her boyfriend in studying the AI.

Is it just me or does Arven look familiar? Even as the thought crossed her mind, she knew the answer. She glanced towards the embankment, her lips pursing tightly.

Meanwhile, the Doctor walked in a circle around the AI, utterly transfixed. Then, coming around to face him again, he leaned in, studying Arven's face. "Wonderful! Who built you?"

"My registered place of activation is the Villiers Artificial Life laboratory in Battersea, London."

The Doctor nodded in appreciation. "You were the pilot who brought my friends safely back to 1910?"

"Indeed," Arven confirmed, a glint in his eye.

"Well, thank you. But tell me, what happened to your arm?" he asked, peering nosily into the empty socket.

"Long story, involves a wall," Rory interrupted. "Let's just say my CV now states that I've performed an emergency amputation on a robot."

"Oh, he's far more than a robot, Rory," the Doctor said, patting Arven on the chest. "Far more than that." He shot a quick glance at Alex, and Alex knew he had also clocked Arven as the AI they'd met on the embankment just a few hours ago, the one who had set them on this terrifying adventure. She gave him a slight nod, signifying her realization. His green eyes shone in admiration of her intelligence, but vanished as he turned to Angelchrist, a nonchalant mask slipping over his features. "What time is it, professor?"

Angelchrist reached into his waistcoat and extracted his timepiece. "Just after ten."

The Doctor nodded. "Then perhaps there's still time," he said, more to himself than the others. He looked as if he were about to say something else, but Amy interrupted him with a question.

"Have you found the source? The hole where the Squall originated? You obviously haven't stopped them yet. . ."

"Yes. The rift was opened three days ago," the Doctor answered, distracted. "The hive is growing in strength and . . . hold on a moment." He looked momentarily taken aback as her words finally registered. "Alex and I have only been here a day!" The consternation was evident in his voice.

Alex's eyes widened as her brain quickly comprehended his words. So caught up in identifying Arven as the same AI they'd encountered in the 28th century, she had completely skipped over the implications of Amy, Rory, and Arven's arrival in the experimental time ship. "Oh my God," she gasped, her jaw dropping in horror.

"A day!" the Doctor repeated. "Not three, like some of us here." He looked reprovingly at Rory, who raised his eyebrows in a 'what, me?' sort of way.

Catching this, Alex smacked the Doctor on the arm. "It's not their fault," she hissed. "They didn't know!"

Amy frowned. "Three days . . . but that's when we arrived, that's when . . . oh." Angelchrist saw realization dawn in her eyes. "Oh. Oh no."

"What is it?" Rory demanded, glancing nervously at the Doctor and Alex. "What's wrong?"

"Three days, Rory! The rift opened three days ago. It was us. . ." Amy looked to the Doctor and Alex for confirmation. Both gave her slight nods, Alex wincing in sympathy. "We were the ones who used the time ship to punch a hole through 1910! We came in search of the Doctor and Alex. Arven even warned us. He said that until that point, the ship had only been used for short, local experiments. We're the ones responsible for allowing the Squall through to this time period in the first place."

"You didn't know," Alex said quickly. No way in hell was she going to allow her friends to feel even an iota of guilt. There wasn't a doubt in her mind that if Amy and Rory had had even the slightest inkling of what their jump in the time ship could cause, they would never have left the 28th century. "The Squall could have just as easily invaded the 28th century as the 20th—"

"Hang on a minute," Rory cut in, raising a hand to ensure everyone was listening. "I don't understand. How can it have been us? Surely that's some sort of paradox? We only came back in time to look for the Doctor and Alex because they came back looking for the monsters. The monsters were already here. That's right, isn't it?"

"Yes," the Doctor said, "but—"

"Hold on. Let me get this straight. What you're describing is an impossibility. Logically, it can't have been us who opened the rift, because the rift already existed before we ever got into the time ship. Simple cause and effect. If it hadn't been for the AI in the river, you and Alex would never have gone back in time to find the Squall, and we would never have stayed behind in the 28th century."

Alex shook her head, wondering how, after so long in the TARDIS, Rory still hadn't grasped the fundamentals of time traveling. "No, Rory, time's not like that."

"She's right," the Doctor nodded. "It doesn't work like that. History is like a. . ." He wove his fingers together and wiggled them around before Rory's face, searching for the right words. ". . .like a . . . a noodley soup of causality, a big bundle of threads. Pull a loose end and it begins to unravel. Events in the future impact events in the past."

"God knows we've all had experience with that recently," Alex murmured, as the Ponds looked momentarily pained.

The Doctor, jaw clenching at the reminder of River, nodded and, after a quick, apologetic glance at Amy, turned back to Rory.

Angelchrist stood watching them from the sidelines, a fascinated expression on his face. Not just for the Doctor's words, but for the dynamics of this whole group, who had clearly undergone an event the likes of which Angelchrist couldn't even begin to imagine. Despite whatever had happened, they were all here, all still together. His heart went out to them all.

"Humans experience the world in such a linear fashion," the Doctor continued. "You live, you grow old, you die. But the universe is vaster and older and more complex than you could possibly imagine. History isn't linear, just because it seems that way. It's a living, changing thing. It shifts with the tides. History is more than the sum of what we experience, and it's not as fragile as you think. There are fixed points, yes," he stopped for a moment to take a breath, "things that have to happen, things that have occurred and will always occur. Those events can't change, can't be altered. Everything else . . . well, history flexes, Rory. Time bends. It tries to assert order on chaos."

Rory frowned. "So, just so I'm clear – the world isn't about to suddenly unravel because everything's stopped making sense?"

The Doctor looked deadly serious, as if Rory had asked the most momentous of questions and he'd honestly had to consider the answer. "No. Reality isn't about to unravel. At least, I don't think so. For now. Assuming we can find a means of stopping the Squall, that is." He ran a hand through his hair and screwed up his face in thought.

Rory didn't look at all placated by the answer he'd received. Alex went up to him and gave him a hug. "Don't worry," she said as Rory wrapped his arms around her. "Remember, we've also experienced how things like this work out in the end."

Rory smiled slightly as he gave her a quick squeeze. "You've got a point," he admitted as he and Alex pulled back, ending the hug.

Amy, after shooting a quick, grateful smile at Alex, stepped forward, looping her arm through the Doctor's. "So, what's next, Doctor? I assume you have a plan?"

The Doctor smiled. "You know me, Pond. I always have a plan."

"No, you don't," Alex retorted, Rory snorting in agreement.

The Doctor pointedly ignored them. "To the TARDIS!" he proclaimed. Detaching himself from Amy, he reached for Alex's hand. Though Alex frowned at the mention of the TARDIS, as well as the memory of what had occurred there only hours before, she didn't hesitate to lace her fingers with his. The couple set off, the amplification device now safely tucked beneath the Doctor's left arm. Amy and Rory, also linking hands, immediately began following them.

Shrugging, Angelchrist fell into step with the artificial man. Surely, he considered, things couldn't get any stranger than this.

~The Pros and Cons of Silence~