Rory considered universal advice as he braced the door against a swarm of future ball-bearings that believed they were his wife. The Doctor needed to include in his rules – if he hadn't already – 'Never say yes when The Doctor comes up with an idea for a really fun day out'. He didn't care what The Doctor said about curses, if one could actually exist, The Doctor definitely had one. Or six. Needless to say, the simulations hadn't taken kindly to his desire to leave. The one that had taken Amy's form had yelled and sobbed so fiercely he had almost been persuaded to stay and console her. And the other …

Hearing the thumping of Amy's fists cease, pure instinct drove Rory to dive away from the door as a hole blasted through its middle. He glanced back in horror at the steaming green gloop that dripped from the wound. "This is why cartoon characters shouldn't be attractive," he deplored, and ran. Bolting down the corridor that he hoped was the one The Doctor had asked him to reach, he very nearly tripped headlong over two figures in his path

"Doctor!" he blurted, goggling at The Doctor-10 who was crouched over his other self, Rory's Doctor. "Plural…" he murmured before taking in the situation. "What happened? Is he okay?"

"I don't know!" The Doctor-10 cried, teeth gnashing in desperation, hands tapping at The Doctor-11's unconscious face. "He said he was poisoned. The messages transmitted into his brain from the simulations told him what had been done to him and his body's reacting accordingly, but I don't know what messages they sent. I'm trying to work out the symptoms, to see if it's something I can fight, but he's not even coming up with a fever. Come on, wake up, you old baby, and give me something!"

At the next tap of The Doctor-10's hand on the fainted timelord's face, The Doctor-11 sat up so fast he sent his younger self sprawling. "Well, the good news is, I'm not poisoned!" he announced, as though he had not been comatose seconds earlier.

"And the bad news?" Rory sought it out reluctantly.

"Oh, Rory! Hello, Rory," The Doctor-11 exclaimed happily. "You got out safely then, I see." He did not look at his friend, staring at the wall in front of him. "Or rather I don't see. That's the bad news. I appear to be suffering a case of total blindness. I'm assuming that you got out unscathed." A frown crossed his features and he inclined his head in the vague direction of The Doctor-10. "Did you just call me an 'old baby'?"

The Doctor-10 resumed his crouching position beside The Doctor-11. "Can we please focus on the fact that you've been blinded? Definitely some sort of psycho-toxin targeting the optic nerves, but I don't think it's stopping there." He brought out his spectacles and put them on.

"I mean, that doesn't even make any sense," The Doctor-11 grumbled. "How can a baby be old? Unless you're Benjamin Button, of course. Ah, Benjamin," he sighed, nostalgically. "That was a sob-fest, wasn' it? Two whole boxes of tissues. What other babies are old? Ooh, there's the people of the Ylyngarian galaxy. Don't break out of their eggs for two hundred years at least. They're very old babies." He carried on babbling whilst his younger self peered into his sightless eyes and laid the back of a hand to his forehead. He did not break off even when The Doctor-10 tested his reflexes, bending his arm at the elbow, tapping his knee, turning his head this way and that. What did stop him, however, was the pressure of a stethoscope-bell as it was slid inside his shirt. "Agh! Cold!" he yelled.

The Doctor-10 concentrated, moving the metal disc from one side of The Doctor-11's chest to the other. He frowned momentarily, took in a sharp breath, and then withdrew.

"What?" The Doctor-11 asked.

"Nothing," The Doctor-10 said quickly. "You're fine. Both hearts working fine. A little faster in rate, compensating for whatever the toxin's doing to your system but there's no danger."

"You've got a look on your face."

"What look? How do you know what look I've got? You can't see."

"You gasped. That means you've got a look. I don't 'ave to see, I just know. What's wrong?"

The Doctor-10 gave a relenting sniff. "Honestly, nothing. A memory. One I shouldn't have because it hasn't happened yet. Anyway, now that you've stopped jabbering on – how are you feeling?"

"Mild dizziness, mostly got my co-ordination though it may be a little off. Slight case of dehydration, bit of a rushing sensation around the eyes and – oh." He stuck out his tongue. "Wha' colour ith it?"

The Doctor-10 squinted. " Normal, no, no, wait. There's some tiny blue spots in the middle…"

"'lue spotsth!" The Doctor-11 repeated, as enthused as though he'd won the lottery. He retracted his tongue. "Okay, great, now we know what it is. Should be much easier now." Getting to his feet, he licked his finger, held it up in the air to attain some sense of direction, turned on his heel and walked into a wall.

Rory caught him before he could fall. "Whoah, easy. Okay, so what does it mean? Is he going to be all right?" He asked the other Doctor. "I'm a nurse and I don't have a clue what this is."

The Doctor-10 rose and took off his stethoscope. "It means he should get back in the TARDIS and rest. He's been contaminated with extract from the black salamander root."

"But it means the blindness is only temporary!" The Doctor-11 said brightly.

"Blimey. How long's the optimism last?"

Rory shook his head. "No, that's just him."

"I reckon I've got about an hour before the raging hallucinations kick in. Except, bearing in mind my metabolism, better make that twenty minutes. Not to worry. Can't be much worse than the aftermath of a proper human stag party, eh, Rory?" The Doctor-11 groped the air for a few seconds before he found his friend's back to pat.

"Um… 'raging hallucinations'?" Rory held up his hands, pleading for a solution.

"We need to get out," The Doctor-10 said, sternly. "Back to the TARDIS, anyway we can."

"What about -," Rory had to hesitate, "Captain Jack? Can I just call him Jack? It's getting a bit weird. Hard to take him seriously."

"That's not necessarily attributing to his name -," The Doctor-11 murmured.

The Doctor-10 frowned. "What's wrong with calling him – oh wait, I see! 21st century Earth, Pirates of the Caribbean! Honestly, he's not the only Captain Jack. He's certainly not the first. Although, he really is very good. Good ol' Sir Johnny." He beamed. "Anyway, I'm sure he'll be fine by himself, our Jack. We left him a message. He'll turn up sooner or later."

Rory's look of disapproval could have uprooted a sheepish mountain. "What? So we're just going to leave him?"

"Rory…" said The Doctor-11. "Jack's not like other humans. I'll explain it to you later, but the crux of it is that he can't actually die. Or at least, when he does, he doesn't stay that way. If the simulations in his room turn nasty, he fares a better chance than any of us."

"And on that basis he can just suffer for as long as it takes us to work out the problem?" Rory retorted. "We have an immortal person on our side and we're leaving him because he's immortal, which also brings me to - thanks. Thanks for not telling me that these things can actually kill us. Might've been useful to know, being that they aren't real in the first place so it's not natural to assume they're properly dangerous." He glowered at The Doctor-11. "All those times you've shown us the power of belief – remembering you, breaking Amy's faith, that…that Tenza and his nightmares. Can't we just know these aren't real and ignore them?"

"These are computer programmes, Rory. You can think all you like at them but it won't change their purpose. Our beliefs are not our friends here. The projectrons – the simulating little robots – can turn your thoughts against you. If they want to hurt us, all they have to do is make us believe we are hurt and our minds will do the rest. You can't even fight it. As soon as a message is sent to your brain, it accepts that message as cold fact and reacts. I am blind because my eyes are certain they can't see, no matter what I might have to say about it."

"I still don't understand why you, of anyone, would leave someone behind."

The Doctor-10's response was curt. "Look, I think dealing with what's happening to him, me, is a little higher on the priority list right now. We won't get anywhere fast while we've got to watch an invalid."

"Oi!"

Rory persisted. "But if this isn't about physical symptoms, what happens if something does happen to Jack? What happens if he gets signals to his brain telling him he can die?"

"He's a fixed point in time," The Doctor-10 disputed. "He literally can't stop existing, ever, unless the point drifts so far it finally breaks down, or the energies holding him together are able to fade, which would take billions of years and that's just in theory, possibly proven theory. Clever computer programmes can't change that."

The Doctor-11 drew out his next utterance. "Oh…"

"What?" The Doctor-10 asked.

"They may not be able to change the code writing Jack continually into the universe, but that doesn't stop him feeling whatever the simulations choose to inflict upon him and simulations won't get bored. If he gets trapped -."

"They could harm him indefinitely, no respite and no escape." The Doctor-10 groaned.

"And of course there's the possibility that if he's convinced he's been dealt fatal damage, his body might continue to believe the lie when he returns from death -."

" – leaving him in a potentially permanent vegetative state. All right, all right! We'll rescue Jack first, but we need to hurry." The Doctor-10 regarded the blind timelord. "And you'll recover a lot faster if you close your eyes. Don't keep blinking. There's a memory for you. Don't blink."

The Doctor-11 curled his lip. "Oh, very funny."

"No, really, I mean it. You'll still be processing all this visual information whether you can see it or not. You need… hang on -." The Doctor-10 drew his sonic and broke the signal of The Doctor-11's hologram clothing, restoring him to his normal ensemble. He stepped up to The Doctor-11 and pulled his bowtie loose. "Just stand still," he instructed before there could be any protest. He whipped off the length of fabric, stepped around behind his older self and blindfolded him. "There we go. Prolonged impairment and crimes against fashion averted." With a grin, The Doctor-10 zapped himself with his sonic and revealed his pinstripe-and-longcoat attire.

"What -?" Rory started, boggling.

"Hologram clothes," The Doctor-10 explained. "All the rage in the 24th century. The practical addition to any wardrobe. Or the lazy addition. Tons of fun, though. Come on then, cripple. Should be this way to Jack's room." He slapped his older self on the shoulder, hard enough for The Doctor-11 to flinch, and walked ahead.

Rory looked to The Doctor-11 with sympathy. "Do you need any help?"

"Nah," was the reply. "I'll be fine. Don't you worry about me." He checked the position of his bowtie and started to walk forward. "Actually…" he said, pausing in his stride. "If you could just point me in the right direction, I should manage from there."

A few moments later saw them catching up with The Doctor-10. He was standing outside the entrance to Jack's room, staring at the curve of the corridor. "Stay where you are," he warned, not turning. "Stay absolutely still."

"Doctor," Rory whispered to The Doctor-11. "Is he talking to us?"

"How am I supposed to know?" The Doctor-11 hissed back, jabbing a finger emphatically at his blindfold.

"Sorry."

In answer to their question, The Doctor-10 greeted whoever was around the corner with a welcoming disposition. "Hello."

"Where is he?" a young female voice, most definitely Scottish, demanded.

"Where's who?"

"My husband."

"Sorry," said The Doctor-10. "Have we met? Give us a clue. If you tell me who your husband is and what you want with him, perhaps I can help."

Another woman scoffed, annoyed. "Duh, she means Rory Williams. You better tell us where he's hiding, or -."

"Wait-wait-wait, just hold on, just one moment!" The Doctor-10 put up his hands to defuse the urgency. "Your husband? But that means -." A grin spread across his face. "Ohhh, you're Amy, aren't you? Hello, Amy, great to meet you! Pleasure, honestly. Even if you aren't actually the real Amy and you're just a cloud of fizzling information. Oh you are gorgeous, and more specifically ginger. Good ol' Rory."

"He's standing right around the corner, isn't he?" Amy arched an eyebrow, arms folding.

"No," The Doctor-10 said quickly. "No, no, he's not. Course he's not. Anyway, what are you doing outside Rory's room? I thought this corridor would be off limits." He looked to the other female. "Hang on, aren't you -? No. No, you couldn't be. Well, I suppose you could be. Are you? You're that green girl from that cartoon. Hold on, what was it? Kim Possible!"

The Doctor-11 pulled a face. "Shego?"

Rory was glad that the timelord was unable to see his expression. "How do you even know who that is?" he muttered.

The curvaceous girl in the bright-green-and- black leotard glowered at The Doctor-10, her black lips turning increasingly mean. A green glow began to cultivate in her right palm. He took a step back, not taking his eyes off her for a second.

"With no admittance that he is in fact anywhere near me, Mr Williams, get ready to run. I'm sorry, I really am, but we're gonna have to. Your next question is going to concern the other me, but just listen, because they're not after him, they're after you and I'm not leaving you to run alone. As soon as I say so, we go, no arguing."

"He's right, Rory," The Doctor-11 admitted quietly. "You have to go. I can't run, I'll slow you down. I'll be all right, but you have to run."

Rory shook his head, another communication that would go unseen. He was desperate to speak, yet somehow he refrained and looked hopelessly to The Doctor-10. "Run!" came the order, and despite how loath he was to do so, he was fleeing alongside the younger Doctor, doing his best to match pace with a man with so much practise.

The Doctor-11 waited in darkness, feeling his hearts still racing from the cruel substance his body thought it had ingested. He felt a rush of air as someone – he assumed the two-dimensional woman – raced past him in pursuit of the other Doctor and Rory. Slower footsteps approached, seemed to be moving past him, but his hearing had not failed him yet. His skin prickled. He could feel the simulation had stopped parallel with him in the corridor.

"I can't help you," he said to the watching Amy. "Look at me, I'm blind. I cannot help you find Rory, and if you try to use me to get at him, the other me won't let it work. Very soon I won't be of any use at all, so be a good girl. Run along, Pond." The ensuing quietness was so thick he thought he could almost hear the tiny machines processing his words. He tensed, preparing for anything untoward, and then he heard her leave.

The Doctor-11 exhaled his relief. He collected his thoughts and then carefully laid a hand on the corridor wall. Sliding his palm along, he picked his way in the direction of Jack's room. Once the cold metal surface could be felt beneath his fingertips, he scratched at his face pensively. Every ounce of his moral fibre was shouting at him to go inside, to be the hero that Jack had always believed him to be. Every other instinct was crying for the opposite. This was Jack, 51st century human with an omnisexual outlook, for him to greet was to flirt – at least it had been. The Doctor-11 had noticed the ex-time agent's lack of audacity, however small. Even so, to walk among the private fantasies of this man would probably have been somewhere on his list of nightmares, right down there with the embarrassing ones like teleporting naked onto old Skaro in front of a thousand Daleks. At least he hoped that had been a nightmare and not an unfortunate future glimpse after a head-clash with River. It wasn't just the idea that he might experience something unpleasant in this room – he'd lived a long time and seen a great many things he would rather have scoured from his brain – but that same old fear ever since Rose Tyler had become the Bad Wolf and done the impossible. Jack Harkness made him want to run and never look back. He was a defiant, gleaming fact that should never have been, as terrifying to a timelord as the Untempered Schism.

And The Doctor-11 was about to go in completely blind. Maybe that was a good thing.

Bringing out his screwdriver, The Doctor-11 patted to the side of the door until he found the access panel. He aimed the humming device at it, satisfied that not everything was deadlocked. The door gave a clunk and slid open. He chewed thin air for an uncomfortable moment and then stepped through.

The first thing to hit The Doctor-11's senses was an alarmingly loud introduction to club music. It boomed on a loop, the vibrations of the bass rattling his skull and causing his steps to teeter. All around he could feel people moving, dancing, the air clogged with myriad scents: humans, other aliens, liquor, sweet altered pheromones that attacked his nose and tingled in his blood. Bodies, warm and not always fully-dressed, brushed past him. Voices giggled and whispered. He ignored them and pushed onward, neither knowing where he was going nor daring to stop. "Not much different from the ballroom, when you think about it," he mumbled to himself. It wasn't long before he bumped into someone that did not move from his path.

"Sorry," he called above the noise. "Please excuse me!"

"Well, this is a new one," the obstruction replied, surprisingly easy to hear despite the din. "You've got your screwdriver out already and I haven't even had time to buy you a drink."

The Doctor-11 swallowed, his fingers twitching awkwardly, conscious of people still bumping past him on the dance-floor. "Jack. You're all right?" It was as though their conversation were filtering through a bubble, allowing them to be heard.

"Oh yeah," Jack exclaimed, "and the way I see it, things are even more all right than they were before. I've not had much opportunity to contemplate the possibilities but I have to say, this new you looks good in submission."

"Before you go any further with that train of thought, Jack, I'm not a simulation. I'm real. Real Doctor." He zapped himself ineffectually with the sonic. "See?"

"And what's that s'posed to prove? That could just be a simulated sonic. Also, the blindfold? If you were avoiding unwanted visuals, you'd only need to close your eyes, and even then I can't see you as being that naïve." Jack stepped closer. "You've been around a long time. I don't see you throwin' around illusions of innocence."

"I'll explain the blindfold later, just please believe me. Trust me. I'm really, truly, me. I thought you were in danger so I came to find you. Rory and the other me are a bit preoccupied, so if it's not too much trouble, I need your help."

Jack laughed. "You came to save me? I'm touched. Gotta be a first. You're already over six months late."

The Doctor-11 frowned, a sickening pang rising in his stomach. "Six months? What do you mean six months?" Though he had a terrible feeling he knew.

"I mean, Doctor, shut up and dance." Jack darted forward and grabbed The Doctor-11 by the braces, snatching handfuls of his shirt to gain a better hold. He spun the timelord out amongst the writhing masses and then held him tight about the waist in waltz fashion, no heed to the pounding club hum.

"No, no, no, don't!" The Doctor-11 blurted, twisting in his grip. "Jack Harkness, listen to me!" He felt the immortal human's hands squeeze. If that wasn't enough to drive the message home, he heard laughter erupt from all around the nightclub. "Ohhh, Jack-Jack-Jack, Jackety-Jack," The Doctor-11 growled to curb his embarrassment. "Trust you to shape a fantasy of yourself." He twirled the sonic screwdriver in the hand Jack was holding aloft and sent a stream of green light into his face.

Jack's image burst apart, and The Doctor-11 heard hell break loose. Hands grabbed for him, dancers shrieked and cried out for him to be seized. He ran, powerless to know where he was going. "Jack!" he yelled, this time calling for the real man. "Jack, where are you?" He kept his thumb jammed onto the disrupting control and waved his sonic frantically, dissipating anything that grabbed at him. "Jack! It's The Doctor! Shout if you can hear me!"

Someone tripped him. He sprawled across the floor. Scrabbling to get up he felt someone kick his screwdriver from his hand. "No! No-no-no! I need that!" He crawled through the fray, one hand over his head to protect himself from being stepped upon, the other desperately pawing in between simulated feet to find his weapon. Hands clasped at his shoulders, tugged at his jacket, trying to haul him upright. Then he found himself pulled forward suddenly, out of the reaches of the crowd.

"Come with me," said a hurried voice. "Quickly, I have to get you out of here."

Warily, The Doctor-11 let himself be tugged along. His rescuer had a familiar accent. He knew this man, but his head was beginning to fill with cotton wool and he couldn't be sure.

"You're here to help Jack?" the man asked, pushing him onward.

"Yes, that's the general idea. I don't think it's going very well to be perfectly frank."

"Yeah, well, can't be helped. Probably to be expected if you're blind. Okay, we're here. There's a door here, right here, feel it with your hand?"

"Yes."

"Jack's through there. Mind out though, he's in a bit of a stick. Can't do any more but I can try and hold this lot off."

The Doctor-11 stared blankly at the man beside him through thick fabric of his bowtie, wishing he could see his face. He was certain now. "Why are you helping me?" he wondered softly. "You're just a computer programme, like them."

The man gave a gentle laugh. "Perhaps you should get to know Jack better. What reason does he have to imagine me any different?"

"I wish I'd known you better," The Doctor-11 replied sadly. He grasped the door handle and pushed through. As soon as it was shut behind him he heard the cries of outrage from the club. He leapt away from the door before they could convince him it could be opened and moved deeper into what must have been Jack's first chamber. The Doctor-11 had only taken a few steps before the screams started. He wanted to run to the rescue. A generation ago he probably would have, burst in blindly, literally. Instead he forced himself to creep around the edges of a room he could not see and would have likely cursed Jack if he could.

Laughter succeeded the screams and The Doctor-11 flinched, dread seeping through his core. It was the same laughter that had flashed in his mind out on the Ood-Sphere, when he had sat with the Elder so many years ago. Oh, Jack. How could you? He edged further along, oblivious to how exposed he might be to the room's occupants. He heard Jack scream again and it turned into broken, brave laughter.

"That all you got?" he shouted. "You're a lot tamer than I remember."

"That's because, this time Jack, I actually give a monkeys about who you are. I only ever wanted to get at him, and you were just a nuisance, a plaything I could kill over and over and over when I got bored, when I wanted to do it to him but didn't. Now I'm back, a warped figment of your imagination, just for you: your guilty secret. I wonder what he'd say if he were here, if he could see you and your naughty mind, one of his sweet little humans. You and I know the truth, though, don't we, Jack? You're all flawed and filthy. You should all be put down like the wretched hounds you are, but oh no, poor you! No dying for you! Bad dog." The Master – who else? – stamped on something wooden, a table perhaps? "But hark! What sound from yonder shadow breaks? Do you want to know what The Doctor would say? Why don't we ask him?"

The Doctor-11 froze.

"Whatever he says, it doesn't matter," Jack sneered. "I know he's not the real Doctor."

"Welllll," said a voice that made one of The Doctor-11's hearts trip. "I might not be. "But he is." Wheels trundled along the wooden floor. Everything else appeared to have fallen poignantly silent.

"Doctor?" Jack choked eventually. "Is that you?"

The Doctor-11 winced, facing the main deck of the Valiant and the horrors therein. Utterly sure he had been discovered; he fumbled for something incredibly clever and useful to say. He came up with –

"Oops."