A/N: From the moment I came up with this story, there were three ways it could go. I only just decided a couple days ago which it was going to be, but I've had to leave clues that were open to each of the three possibilities. One of the things I enjoy about Doctor Who is that the character of the Doctor isn't infallable. Sure, he's usually right, but every now and again there's a twist at the end that even he didn't see coming. Sometimes he barks up the wrong tree. It's those times when it's the companion's job to reel him back in, which is what I was going for here.

The corridor continued around in a circle surrounding the station, and Quinn stepped through the door at the other end apprehensively. "I still can't find anything that looks like a doctor's station," she said. "Somebody had to be in charge down here."

"Dr. Snow, what else is on that deck?" the Doctor asked.

"Besides the mess? Not a lot. There were some offices... accounting had their offices down there, I think, or maybe it was HR... and then the cargo bays."

"Cargo bays? I didn't think there were any docking points on the whole station."

"There aren't. Everything needed to be teleported aboard - patients and staff, sure, but also all our supplies. There are massive teleport platforms in the cargo bays, to get bigger equipment and supplies into the station and have a place to store them."

Quinn had been following the only path open to her this whole time, and she was now standing outside a large, heavy door. "I think I might be at one of the cargo bays now," she said, checking the sign on the door. "Cargo Bay B."

"Open the door," the Doctor started to say, but Snow shouted over him.

"No! Get out of there," the old man yelled, more emotionally than he'd said anything since they'd met him. "Do not open that door, whatever you do! It isn't safe, isn't safe..."

"What is it, Dr. Snow?" the Doctor asked.

"No, no, no, no, no, no, no," Snow whimpered. Great, Quinn thought. He picked this moment to turn into a lunatic. "Mustn't go in there, mustn't look..." Quinn didn't notice that anything had been different until the change happened, but as Snow continued to whimper the light in the room she was standing in suddenly shifted to become blue, like the rest of the deck had been. As soon as that happened, a heavier blast door slammed shut over the door she'd been about to open, and she took a started jump backwards.

"Doctor!" she called. "Whatever this thing is, it's in this room! The lights just changed!"

"Something's wrong," the Doctor said. "Something isn't adding up here." He drummed his fingers on the security panel, thinking, and then asked, "What does the scanner say?"

"What?!"

"The scanner! The medical scanner you're carrying, what does it say about the room?"

"It says..." she peered at the device. It hadn't changed one bit since she picked it up. The readings were identical. "It says nothing's wrong," she said. "But maybe it can't detect whatever it is."

"They're the same scanners," the Doctor said. "Diagnostic units are the same, hand held or not. If that scanner says the room is clean then there's no way the alert should have been tripped. None!"

"So what does that mean?"

"That someone or something triggered the alert manually." Quinn tried to wrap her head around the idea. Who would do such a thing? Who would be capable of it? "This is just too much coincidence," the Doctor continued. "Ever since we got here it's been one disaster after another. We show up for a simple visit, and there's not a soul to be found. Then the station's damaged by an asteroid, even though the shields should have seen it coming miles away. The whole thing gets shut down and conveniently, we can't power it up again. The command deck's locked off completely; if there hadn't been someone already in here the whole thing would still be shut down. And then, just when we're on the verge of finally making it out of here, you show up, Dr. Snow, sending us off on some tangent about quarantine protocols."

Snow didn't respond. He just kept muttering about some kind of danger.

"What does all this mean?" Quinn asked.

"This station isn't behaving rationally, not by a long shot," the Doctor said. "In fact if I didn't know any better I'd say it was depressed, manic, trying to kill itself."

"Space stations get depression?"

"It's not exactly common, no," he said. "But it won't even let me review the security logs to see what happened here. Somehow this station is in denial."

"No, no, no," Snow muttered. "I'm sorry. I'm sorry, I'm sorry, just don't go on. Don't go on. Don't go in there."

"And look who finally grew a conscience!" the Doctor said, and even so far away Quinn could hear the sneer on his face, the same one he got whenever someone had done something that completely disgusted him. "What'd you do, lay a trap for us?"

"No..."

"What are you after?"

"Nothing! I haven't done anything!"

Something still wasn't right. There was something she couldn't quite put her finger on, something about the quarantine deck she'd seen so far. What was it?

"And worse still," he Doctor continued, "you killed everyone on this station to do it! Staff, patients... it's clear they were set up to deal with an epidemic of huge proportions. How many people? How many lives?"

"Doctor..." Quinn said, hoping he'd get the message, but he barreled on with a full head of steam. Suddenly it hit her. The Doctor said that so many people had died from whatever plague had swept through the station. But if that was the case, if thousands of people had really suffered and died here, then why were all the beds neatly made? It didn't look like any of them had even been slept on.

"When did you start calling yourself Alden Snow, anyway?" he asked. Dr. Snow had long since stopped denying anything. Now the poor man was openly weeping. "I'll find out what you're doing, I'll stop it, and then I'll make sure you never harm another living thing in the universe if I have to dismantle every single code block myself!"

"Doctor, stop it!" He'd been going on and on about the deaths, and that's when she realized it...

"No," he replied. "I'm taking this computer down. Because that's who you are, right Dr. Snow? You're the onboard computer system for Mercy Station!"

Quinn rolled her eyes and lunged for the door controls, flinging the doors of the cargo bay open wide. "Doctor, SHUT UP!"

Up on the control deck, an indicator cheerfully yellow to indicate that the door had opened. The Doctor stopped his diatribe to look over at the panel. "Quinn, no!"

It even seemed to snap Dr. Snow back to consciousness. "Get out of there. It's not safe!"

She stepped through the door to the cargo deck, coming out on a narrow gantry overlooking the bay below. It was huge, bigger than a football field and about twice as tall as the gymnasium back at school. Just like the cafeteria, the entire place had been converted to a triage facility, with lines and lines of cots. And she'd been right, about what she noticed earlier. Just like the ones in the cafeteria, they were all perfectly clean and perfectly made. Not a single one had been slept in. "It's alright," she said. "Doctor, the cots.'

"What about them?"

"Nobody's used one. If there were really a sickness, if Dr. Snow had really plotted to kill everyone with some disease or something, then wouldn't they all have been used?" There was silence on the line. Quinn descended the metal framework stairs and sat on one of the cots, stroking the smoothness of the blanket. The quiet was broken by another round of quiet sniffles from Dr. Snow. "Dr. Snow?" she prompted quietly and tenderly. When he didn't respond, she tried a more personal touch. "Alden, what happened?"

"I... I can't say..."

"Yes you can."

"No, please, don't make me think of it..."

"Alden," the Doctor said, his voice soft again, "where are you?"

"At a security panel," he replied. "Like I told you."

"And where is that panel?"

"What?"

"Where is it? Where on the station?"

"It's on the command deck."

"No, it's not," the Doctor said.

"Of course it is! I think I know my own whereabouts by now."

"I'm sure," the Doctor said. "But I'm on the command deck. And you're not here."

"No, but... that can't be."

"Alden, I'm standing on the command deck, right next to the security station. And I'm quite alone."

"But..."

"Can you see the planet from where you are?"

"Yes, of course. It's right outside the window, clear as day."

"What color is it?"

"Red! Just like it's always been."

"This station is in orbit around a brown planet," the Doctor said. "And furthermore the entire station is surrounded by a cloud of tiny sapphire particles."

"There's nothing out there," Snow insisted. "Just clear space! Nothing! This is ludicrous!" he sputtered. "I'm not listening to any more of this."

"Doctor Snow," the Doctor said, "how long has Mercy station been in operation?"

"What? What does it matter?"

"Just curiosity," the Doctor said.

"Well, now, I... let's see. I've been here about five and a half years, give or take a couple months, and I think the station had been built about a decade before that, so..."

"Computer, state system uptime," the Doctor said, interrupting.

Snow stopped speaking mid-sentence and, slipping into a slight monotone, said, "Sixteen years, five months, twenty-one days, ten hours, four minutes and fifty-eight seconds." Then he gasped, seeming surprised at what he'd just said.

"Nobody measures time that accurately," the Doctor said. "No living thing, not unless you're a Time Lord. That response was pure mechanical precision. Just like a computer."

"No, no, no! You're mistaken! I am not a machine! My name is Doctor Alden Snow. I'm a medical oncologist assigned to Mercy Station. I treated hundreds of patients over the course of an illustrious career until..."

"Until what?"

"I..."

"I know it's painful," the Doctor said. "But you have to remember! What happened here?"

"No. I don't want to... think about it! Leave! Just leave me to it! I can handle this myself. I don't need anyone!"

"We can't leave until this lockdown is lifted, and that can't happen until you remember. You have to remember!"

"Just leave me be! Let me rest!"

Quinn sat cross-legged on the cot, hands folded in her lap. Beneath the transparent face mask, tears had begun to fall. She understood what it was like to have painful memories you didn't want to turn back to. Her heart broke for Dr. Snow with every harsh, ragged breath he took. "Doctor, don't force him! There's nothing he can do!"

And then, taking a deep breath to calm himself, Snow said through a quiet, still-shaky voice, "Oh God. Oh my God. I am Dr. Alden Snow. I am human, I'm an oncologist, I am a physician at Mercy Station. And... I remember."

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