"What's it doing now?" asked the Doctor.

He was flat on his back, buried deep in a mass of wires with his head beneath the TARDIS console. Having discarded his brown suit jacket, he had his shirtsleeves rolled up as he worked. He was trying the sonic screwdriver on various settings, but none seemed to be working.

"It's still got 'buffering' on the screen," said Donna, who had been told to stand by the scanner and keep an eye on technical readouts that she didn't entirely understand.

"Nine-hundred years of time and space," mumbled the Doctor, "and I've never met anyone who knows what that really means."

They had been planning to go to the holiday planet of Paradise Max, where having a good time wasn't optional: the guests had all their negative emotions taken out of their minds upon entry, so they had nothing to worry about during their break. That sounded like a good idea to Donna, but their trip had been interrupted when the Doctor decided to accept an incoming message from an unverified source.

The Doctor wrenched a panel open beneath the console, causing a cloud of dust to pour into the room. Most of it seemed to end up on Donna's floral blouse. She wiped it clean, and sighed heavily. The Doctor didn't seem to notice.

"This message might be some sort of virus," Donna warned him. "And you don't want one of those. Especially a Trojan horse, they're a nightmare. I tell you, whoever invented those wants shooting."

The Doctor's silence was telling, mainly because it was the first time that day that he hadn't answered her back.

"Oh, you didn't?" she accused.

"I had a bit of trouble," said the Doctor, "trying to save the world on one of those old computers. You know, the ones that the same size as the average house? This was back in the early days of the Internet. Anyway, I may have invented the Trojan horse virus. Sorry."

Donna shook her head in disbelief, but she was also smiling. Even after all this time with him, the Doctor was still full of surprises.

"Next you'll be telling me that you came up with the idea for the original Trojan horse, too. You know, the wooden one."

Once again, the Doctor remained silent.

"No way!" Donna laughed.

"Funny how people can take some things so literally," said the Doctor.

He clambered up off the floor and joined Donna by the scanner. Ancient Gallifreyan symbols on the display twirled and spun at a bewildering speed, and the word 'buffering' hovered above a bar that was slowly filling up.

"What were you trying to do?" Donna asked.

"Well, in order to let that transmission get through to us," the Doctor said, "I deactivated the Zeiton filter, recalibrated the universal wavelength interceptor, and rerouted the firewall through the fluid link converter."

"Oh," said Donna, understanding not much but enough. "I can see where you went wrong." She proceeded to give the TARDIS console a great whack that, much to the Doctor's surprise and delight, made the incoming message load almost instantaneously.

"Well done, Donna!" he said brightly. "And never, ever hit my TARDIS again."

"Oh, shut up and read," she said, pointing to the words on the scanner screen.

Dearest Doctor,

I would like to invite you to the Benuvian Royal Family's Coronation Celebration. It would be a great honour if you were to accept our invitation and attend with any guest(s) of your choice, as a thank you for saving our world and its people from the darkness of the universe. The space-time co-ordinates are attached to this transmission. We look forward to seeing you at the party.

Yours eternally,

Princess Petallia x

"Hold on," said Donna as the Doctor hastily deactivated the scanner. "What was that last bit? Did I see a kiss?"

"Princess Petallia..." said the Doctor, staring off into the distance, seemingly lost in thought. "Lovely girl. Nice hair. Four arms, too. Always a bonus."

"If you say so. Are we going?"

"I promised you a holiday," the Doctor said, "so I can't just divert us without asking. I will say the Benuvian's know how to throw a knee's up. So, what do you think? Paradise Max where you won't remember why you weren't having a good time before you got there or a coronation celebration you'll remember the rest of your life? Up to you."

Donna looked at him. She tried not to give anything away, to keep the Doctor in suspense as he did to her so often.

After a moment, she broke into a smile. "I think it's party time!"

The Doctor grinned back at her, and slammed a lever on the console.

Doctor Who

Reversed Polarities

The Immortal One

By Samuel Marks

The TARDIS door opened with a creak, and the Doctor stepped out into a dark, cramped space. When Donna followed, a bottle of red wine of dubious origin clutched tightly in her hands, it was even more crowded.

"I told you," said the Doctor, "you didn't need to bring that. No telling just how long it's been in the TARDIS wine cellar."

"I don't know what parties are like for you on Mars," said Donna, "but where I come from, you turn up with some alcohol or you don't turn up at all."

"That's all well and good," said the Doctor, activating the light on his sonic screwdriver, "but..."

"Oh, let me guess. The Royal Family doesn't drink wine."

"On Benuvia? They have a very unusual relationship to, uhm, spirits. Now, on Vindasi-Prime, it's a whole other story," he told her. "No wine for that lot, but they do have a fondness for stew and beer, well, it's sort of like beer, except that it's made from—"

"Enough already, Chef Ramsey. Did I pick the wrong vintage, then?" Donna asked, squirming a bit in the tight space. "Are these Benuvian Royal Family people going to be offended by our little gift?"

"Nope. They'll love it. In fact, they're made of it. Running through their bloodstream, permanently. That's why they're such good fun. It's even worse for them in the mornings, though, with their hangovers. Not, I should add, that I know what they're like in the mornings."

"Not even your friend Princess Petallia?" asked Donna, with a smirk.

The Doctor just winked at her.

"Anyway," she said, looking around at the darkness, "where are we? Bit cramped in here, and no signs of a party."

"This looks like," said the Doctor, "a cupboard. Come on, let's go!"

He buzzed the sonic screwdriver at a door concealed in the shadows, which swung open. The time-travellers stepped through into a long, metallic corridor that stretched out before them for what looked and felt like miles.

"Hear that?" he asked, after they had been walking for a while. "Anti-gravity engines. Level seven perpetual orbit enablers. Bit primitive for the time period, but they do their job."

"So we're on a spaceship?"

"Close," said the Doctor. "A space station."

Ahead of them, a short distance away, was a computer terminal built into the wall. The Doctor hurried over to it, whipping out the sonic screwdriver again. Donna didn't bother to read all the information that was displayed on it, suspecting that her Time Lord friend would probably explain it all to her soon enough, most likely faster, clearer, and with additional useless information.

"Oh, this is the Watchtower!" he said, popping on his glasses as he studied the scrolling lines of information. "Remarkable place. Part military installation, part science base. Located on the edge of your universe, looking out onto the next. Humans use it to keep a look out for any dangers. You lot are so paranoid!"

"Not Benuvia then?"

"Ehm, no. Not Benuvia. Not even the same quadrant of space. Not even the same time period. According to this, it's the year 4114," he said. "A palindromic number, lovely! This day's getting better and better. Aside from this not being where or when we were headed that is. We've been to this century before, though. Do you remember? Planet of the Ood, in 4126?"

Donna did indeed remember, although that seemed so very long ago now. All the places they had been, all the things that they had done since then. Sometimes it felt like she wasn't even the same person anymore. Being with the Doctor had changed her, more than she ever thought possible.

"Yeah," she said, "so... no party? I wore this dress and these shoes, and there's no party?"

"I, uhm, no," said the Doctor. "No party. You look lovely though. Thing is, something's wrong. Where is everyone? I'll run a search for life signs."

He turned his attention back to the computer terminal, but as he did so, the screen flickered and then died, like someone had turned the power off. None of the sonic screwdriver's settings seemed able to restore it. Something was, as the Doctor had suspected, definitely wrong.

"Someone's drained the power and diverted it," the Doctor told her, folding his glasses back into a pocket.

"What now?"

"Stay close," he said as they continued to explore the Watchtower.

The young soldier was slumped against the wall. His gun, still fully loaded, lay next to his lifeless body. He couldn't have been more than twenty years old.

Even after all she had seen, Donna was still moved by the loss of life. Any loss of life, really. It didn't matter if it was human or alien. But the Doctor... he seemed indifferent to the tragedy as he silently examined the body, commenting about blast patterns and necrosis and morbidity. Watching him, Donna wondered if he had lived a life so tainted by death that it no longer affected him. Or was it a mask? A brave face he wore while she was around. She needed him to remain strong, so that's what he did, always hiding his true feelings for her benefit. She supposed, in moments like this, when they were faced with the terrifying reality of life and death, he must feel something.

"He's dead," the Doctor said simply. "Been like this for about twenty-four hours. We're a day too late."

"How?" Donna asked as she turned away, peering down the dimly-lit corridor. She was holding back the tears, and that one word was all she could manage.

"Electrocution, by the looks of it," he said. "Some sort of amplified electrical charge, applied directly to the head. Look—there are burns on the forehead. No signs of a struggle, no ammunition shells in sight. It was probably unexpected. I told you something was wrong. Maybe someone else here knows what happened. We should find them. Keep an eye out for any survivors."

Donna had been on the brink of tears for a while, but only now did her emotions overwhelm her. She had seen something terrible that she knew would haunt her dreams for weeks.

"Hey, it's all right," said the Doctor warmly, going over to comfort her. "We can solve this, Donna."

She realised that he hadn't seen it yet, and it pained her inside to know that she had to show him. She couldn't find the words to express the horror, so she simply pointed at the section of the corridor behind the Doctor.

There was another dead soldier, and another, and another. A great row of lifeless bodies all along the corridor, as far as the time-travellers could see.

The Doctor looked on, holding Donna in his arms as she wept, holding her so tight.

They followed the trail of the dead down to the lower levels of the Watchtower, in the part of the space station that had previously functioned as a scientific research centre. The Doctor thought it likely that whoever or whatever was behind the attacks could still be on board, so he told Donna, and instructed her to keep to the shadows, just in case.

"I don't understand," said Donna quietly. "What about that message from your friend? Was it real?"

"Might have been—at some point," the Doctor said, as they made their way through the dark. "I expect it was intercepted and turned into a trap to get us here. Exploiting my relationship with the Princess, and our love of a party. And now my love of a mystery. Someone wanted me here for a reason."

"Why?"

"Very good question."

Donna looked down at the bottle of wine that she was still holding onto, rather pointlessly. She should have known better than to think they could have a relaxing evening. Nothing was ever that easy when it came to the Doctor.

"Looks like we won't be needing this," she said, dejected.

"Oh, keep hold of it for now," the Doctor replied. "We can celebrate being alive, if we do actually manage to get out of here."

He didn't seem confident that they were going to survive. The death of so many soldiers had deeply affected him, no matter his lack of response. When the Doctor was afraid, Donna knew that she should be, too.

Up ahead, the two of them heard movement: footsteps. And they were getting closer. The Doctor and Donna scurried to one side of the corridor, ducking down behind a stack of supply crates. They peered over the top of them, seeing a single Ood pass by, unaware of their presence. A strange blue light shone out from its eyes, illuminating the shadows with an otherworldly glow.

The Ood stopped a short distance away, busying itself at a wall terminal, where it unplugged various wires and reconnected them again in new combinations. It looked like an intricate procedure, but the Ood seemed confident in what it was doing. Sparks exploded outwards at various intervals, but the Ood didn't flinch.

"That's an Ood!" whispered Donna, when she thought they could speak freely.

"Quite right. It must have been here serving the humans, when they were still alive."

"But we freed the Ood," said Donna, confused.

"Yes, but in the future," said the Doctor. "Relative to this point in time. It's in the future, but it's in our past." He gave an exasperated sigh. "Listen, Donna, can we discuss the infinite complexities of temporal mechanics when we're not in the middle of a mystery?"

Donna nodded, and turned her attention back to the Ood.

"What's it doing?" asked the Doctor under his breath. Donna hoped that he wasn't expecting an answer. "Looks like he's rerouting the power into one single system—but why? What's all this for? Stay here. I'll just go and ask Mr Ood what he's up to."

The Doctor left his hiding place and walked down the corridor, making no efforts to hide his presence as he approached the Ood. Donna hurried after him. There was no way she was going to sit and wait in the shadows. Standing right next to the Doctor was the safest place to be.

Alerted to their presence, the Ood turned to face the Doctor and Donna, its eyes glowing an ethereal shade of blue.

"Hello!" the Doctor said, smiling confidently. "What are you up to?"

The Ood didn't move a muscle as the Doctor popped on his glasses and began examining the displays on the Watchtower's computer systems. It stood completely still, staring at him, as if studying him, trying to work him out.

"Fascinating! It looks to me like you're trying to create an inter-dimensional warp hole, ripping a crack in the very fabric of space-time to access an area beyond knowledge and understanding. Clever plan—brilliant plan." He whipped off his glasses and looked the Ood right in its eyes. "But it'll never work. You'd need all the power in the universe to tear this reality apart."

Slowly, the Ood picked up its translation sphere, which gave off a hum of power. For a while it said nothing, until the ball glowed with that same blue light, and a voice that Donna could tell was not its own emerged from it.

"And yet," said the Ood, "we have two."

"What?" the Doctor asked.

"Two universes. Remember, Doctor, that we are on the boundary between one universe and the next. Think of the power running through this place. Unlimited power!"

With an animalistic cry unlike anything Donna had ever heard, the Ood reached out and slammed a lever on the nearest control panel.

Sparks burst forth and the electricity flowed through the alien's body. It shook and convulsed and shrieked in pain before being blasted backwards across the room, its seemingly lifeless body slumped in the shadows, buried in the darkness.

But there was a greater problem facing the time-travellers: the whole space station was shaking beneath their feet. They steadied themselves on whatever they could reach out and grab hold of.

"What the hell is going on?" asked Donna.

The Doctor didn't answer. He could only look on in a state of wonderment and disbelief as what could only be described as a miniaturised lightning storm burst into life and crackled in mid-air. Donna shielded her eyes from the blinding flashes, but she noticed that the Doctor just looked on in awe, as enraptured by the light as he had been back in Ireland by what they thought was a fairy.

After what felt like far too long, the localised lightning aboard the Watchtower subsided. But as it disappeared, something else was left in its place, suspended in the air, floating in its place.

"It's a portal," said the Doctor.

He made his way over to where the glowing gateway swirled in the air. Blue energy—the same colour that had poured out of the Ood's eyes when it had been possessed by the mysterious energy—sparked around the edges of the portal. As the Doctor reached out to touch it, the lightning seemed attracted to his fingertips.

Donna had so many questions she needed to ask her Time Lord tour guide, but someone else spoke up first. It was a deep, booming voice—the same that had spoken through the Ood.

"Greetings, Doctor," said the disembodied voice.

"Hello, whoever you are," the Doctor said. "Do you want to fill us in? What's going on? And who exactly am I talking to?"

"I am forever," said the voice. "I am eternal. I am ancient and undying. I dare to defy death. Do you dare to defy me?"

"Oh yes!" said the Doctor. "But there's more, isn't there? You know who I am. You summoned me here, under false pretences—why do that? What's all this for?"

"Sorry," said Donna, interjecting, because there was just too much that she didn't understand about the whole situation, "but where's that voice coming from?"

"Through there." The Doctor gestured towards the portal. "That looks, to me, like a fast-track into another world—another dimension. That voice is speaking to us via the portal, calling out to us."

"So we're safe, right? It can't hurt us from wherever it is?"

"Yep. Totally safe."

But even as he said it, Donna knew he was wrong.

The bottle of wine in her hands shattered, a thousand tiny pieces of glass exploding around them. She shrieked as she dropped what remained of the bottleneck. Her party dress dripped with wine as red as blood. She glared at the Doctor, but he could only shrug an apology.

"Or not so safe," said the Doctor. His eyes darted around the room, and Donna thought that she could almost hear the cogs whirring in his brain. "So, look at you! You can reach out of your world and interact, to an extent, like how you controlled the weak-minded Ood, influencing it and telling it what to do, to harness the Watchtower's energy and open the portal to your dimension."

"Yes, Doctor," said the voice. "And I can also do this!"

In one swift motion, the Doctor was swept from his feet and lifted into the air. He floated helplessly for a few moments before being pulled headfirst into the portal, protesting angrily as he went. As soon as his trainers were through, into wherever it was that he was being taken, the portal winked shut behind him. The lightning storm fizzled away, until there was nothing left but silence.

Donna froze. Now what was she supposed to do? She was all alone...

But she wasn't alone for long: the Ood was on its feet, its eyes glowing bright blue in the darkness as it advanced towards her.

Suddenly Donna knew exactly what she needed to do, because nothing else could be done. It's what the Doctor did in these situations.

Run!

Donna hurried through the maze of darkened corridors of the Watchtower in search of the TARDIS. The Ood was close behind—and was getting closer with each heavy footstep. Donna could hear the crackling of electricity from the Ood's deadly translation sphere.

It was ready to kill, but she wasn't ready to die.

Reaching the TARDIS not a moment too soon, Donna dived inside. She stood, breathing hard, with her back to the door. There was no way that the Ood could follow her now, but that did little to reassure her. However firmly she tried to tell herself that things were going to be all right, that she was safe and wouldn't be killed, there was no escaping the fact that she was trapped. And alone.

Again.

Donna looked over the mad array of controls on the main console, unsure of what to do, or what she could do without accidently blowing a hole in the universe. The Doctor had tried to teach her on numerous occasions but, as was often the case, she hadn't really listened. She had been so interested in having fun, larking about in time and space, that she hadn't worried about the serious stuff. The end of year exam was here, and she'd been at the back of the class all term, messing about and making jokes. Her only hope of passing—and therefore surviving—was for her very best friend to help her.

But that was impossible, because the Doctor was gone.

But he couldn't be. Donna refused to believe it, even though the evidence seemed to suggest that she was, in all actuality, alone at the edge of the universe. She had been alone before, but never for long. He always found his way back. Surely he would find his way back now. Or, she would find a way to him before the TARDIS automatically took her back to Earth. If that happened... she would never be able to help the Doctor.

She squeezed her eyes shut and tried as hard as she could to conjure up the memories of being the DoctorDonna in her mind. Her knowledge of the TARDIS and all of time and space would have helped her to get out of this terrible situation. She couldn't remember wanting anything more than to reinvigorate her memory. But it was no use. Without the Doctor there, by her side, smiling at her and telling her that everything would be okay, she just couldn't do it.

Mourning the loss of her Time Lord best friend, she almost forgot that a possessed Ood was waiting just outside a set of wooden doors, ready and more than willing to kill her. She expected it to be pounding its fists against the doors, desperate to break in, refusing to give up the chase and surrender its prey—but no, it was not doing anything at all.

"Hello?" asked Donna nervously, calling out.

An unexpected reply came.

It was the Doctor's voice.

"Donna, it's me. Open the door."

She didn't believe it. He was gone—been taken into another dimension—she'd just watched it happen, and been unable to stop it. How could he be talking to her now?

"It can't be you," she said accusingly. "It just can't!"

"Go to the scanner, see for yourself."

Donna hurried up to the control console and looked around for the required switch. Again, she didn't know what to do.

"The big red button!"

It seemed to be the Doctor's voice, and it seemed to be his mind behind it as well. He obviously knew Donna well enough to understand that she didn't have a clue what she was doing. At first she had thought that something was using his voice, channelling it to manipulate her—but now she wasn't so sure.

She pressed the required button, and the scanner flickered into life. It displayed footage of what was going on outside the TARDIS doors, as if a camera was concealed in the light at the top of the blue box. She hoped to see the Doctor stood there, having vanquished the Ood and saved the day.

That, too, would've been too easy.

The Ood was still stood there, outside the doors, though it didn't quite seem itself. Its translation sphere had been pinned back onto its uniform, and its now-free hands were stuffed into its pockets. Its legs were spaced wide apart, and it swayed backwards and forwards casually. Donna had never seen an Ood poised like that before. In fact, she had only ever seen one person stand in a manner so confident and carefree: the Doctor.

"It's you!" cried Donna, not quite believing it.

"Course it's me!" said the Ood with the Doctor's voice. "See, the thing about the Ood is their minds are weak, open to influence. That's why the inter-dimensional entity was able to overwhelm this one so easily—and I could do the same. Just takes a bit of concentration and meditation, that's all."

"But you went through that portal!" Donna said. "Where are you?"

"A dreadful, terrible place, Donna. It's a nightmare, honestly—but being inside this poor Ood's head isn't much better. There's only one way we can win this. And I need your help. So hurry up and let me in!"

Donna ran down to the TARDIS doors and threw them open. The Ood hurried in, rushing up to the console, immediately and expertly flicking switches and slamming levers like an expert—like the Doctor. In Donna's mind, there was no doubt about it: it really was him.

"Shut the doors, then!" said the Doctor-Ood. "I've only got so long before the Ood gets overwhelmed—my mind's a bit too complicated for it, so it won't be able to hold my consciousness for long before it falls into a coma."

Donna did as she was told, closing the doors, allowing the TARDIS to take flight. The groan of the engines filled the air as the time rotor began to rise and fall. The Doctor-Ood looked up at it, watching it intently, apparently satisfied. Donna found it difficult to tell if it was pleased, seeing as it had no mouth—its tentacles weren't exactly capable of displaying a great deal of emotion.

Nervously, she approached the creature. It turned to face her, holding its arms out, encouraging her to give him the great big hug that both of them needed. But Donna wasn't sure... Could it really be her Doctor in there?

"Donna," it said, "it's me. I promise you—I'm the Doctor."

"No," she said, shaking her head. "I mean, I believe you—I think—but there's no way I can call you the Doctor. Not when you look like that."

"Oh, call me whatever you like," said the Doctor-Ood, "but remember that the TARDIS has a profanity filter!"

Donna smiled and, from the way that the creature's tentacles twitched and started to foam, she assumed that the Doctor-Ood was trying to do the same. They hugged, holding each other so very tight. The Doctor-Ood didn't even seem to notice that Donna was soaked with wine—or perhaps he simply didn't care. He just seemed so happy that they were working together, as a team, despite being worlds apart.

But the rumblings of the TARDIS interrupted them, and the Doctor-Ood turned its attention back to the time machine's controls.

"I thought you said no one but you could work this thing—I mean, you you, not that you aren't you, but you know."

"Let's just say I've got her on autopilot. Any minute now, I expect something else is going to take control..."

"Something else? You mean that thing? You're letting that thing take control of the TARDIS?"

"Oh, yes! Hang on tight!"

"Why? Where are we going?" Donna asked, shouting over the noise of a particularly turbulent flight.

"Into another dimension!" said the Doctor-Ood. "We're going to rescue, well, me!"

The TARDIS spun and tipped and rolled violently until, after far too long and far too much discomfort for Donna's liking, everything was calm again. When she opened her eyes, she saw that the Doctor-Ood was slumped on the floor, completely still. It had, as the Doctor had said, been overwhelmed by the powerful mind of a Time Lord.

Donna hurried over to it and saw that the creature was still breathing. As relieved as she was to see that the Ood was still alive, she realised that once again she was on her own.

It was all up to her to rescue the Doctor.

Assuming that the Time Lord's questionable piloting skills had, on this occasion, actually brought them to the right place, Donna headed for the doors, bracing herself for whatever was on the other side. She had no idea what would be out there—only that it was some other dimension, whatever that meant. The Doctor had described it as a nightmare... That certainly didn't sound good.

She reached out a trembling hand and opened the TARDIS doors. Stepping outside and looking around, she couldn't believe what she saw.

The sky was a glorious shade of blue, interrupted occasionally by the pleasant sight of wispy white clouds that floated along gracefully. The TARDIS was parked on a mighty hilltop, allowing Donna, as she stepped out, to look out onto seemingly endless rolling fields and pastures. The joyful cries of young children carried up towards her, and she saw them playing far below. They didn't have a care in the world—they were just so happy, and calm and peaceful.

Shielding her eyes from the glow of the midday sun, she searched for the Doctor. As concerned as she was for her best friend, all she could think about was how wonderful this place seemed. It certainly wasn't like any bad dream she had ever had, and she wondered why the Doctor would describe this to her as a nightmare.

It was the perfect place.

"Donna?"

She turned around, seeing the Doctor emerging from behind the TARDIS. He hobbled over to her, like it hurt him to walk. It seemed as though it was an effort for him to even stay on his feet. Donna hugged him, so pleased to see him, but he let out a cry of pain.

When she let go of him, he fell to the ground. He was panting, unable to catch his breath, or say anything else.

"What's going on?"

The Doctor was in no position to answer her, but she knew that the spirit being occupied this world—it was obviously around here somewhere.

"Tell me what you're doing to my friend!" she said, shouting at the sky. She couldn't stop herself from crying, as she realised just how much pain the Doctor seemed to be in. "Show yourself you big whatever-you-are!"

"Regretfully," boomed the disembodied voice that had previously spoken through the Ood, and later the portal, "I cannot show myself. I have no physical form—not yet, anyway. I am the Immortal One."

"Stop it! He's in so much pain! What are you doing to him?"

"This dimension is not fixed—it is malleable. I can mould it to my will. I can make of it whatever I desire, create any reality from your fondest dreams or your deepest fears. I created this place as the Doctor's own personal nightmare. This is a world that no longer needs him."

For the first time, Donna saw it. Everything was calm and peaceful and perfect: that was why the Doctor described it as a nightmare. Nothing was in danger—there were no monsters on the loose, no spaceships in the sky, and no apocalypse on the horizon.

Heaven for the universe was hell for the Doctor.

"No," Donna whispered. "I don't believe it. I don't believe you!"

"Soon," continued the voice, "the Doctor's spirit will be broken."

"Why are you doing this?" she cried out.

"If I break the Doctor's spirit in this dimension, then his soul will be opened, and I can feast on it. The countless lives of a Time Lord will be mine for the taking."

"But why do you need that, if you're already immortal?"

The voice did not reply. There was only silence.

With what little strength he had left, the Doctor started to laugh.

"Do not mock me, man from Gallifrey," said the voice. "I will break you!"

Donna wondered what the Doctor found so funny. Even in the darkness, as his worst nightmare surrounded him, he found a way to laugh at it—that was how he survived, smiling through the pain, each and every day of his life.

"Hold on," said Donna. "You said all that stuff about being eternal and everlasting—and you even named yourself the Immortal One—but you're not actually immortal? What kind of a rubbish all-powerful-being are you? You've given yourself a name that assumes your plan will be successful?"

"Soon it will be."

The Doctor gave a terrible cry, his laughter dying away. Donna turned toward her friend feeling so helpless. He lay flat out on the grassy hilltop now, next to his TARDIS, seemingly close to death. A mysterious beam of bright white light burst out of the perfect sky, and slammed down on the Time Lord.

"The Doctor's spirit is broken! I will feast on his soul! Immortality will be mine!"

"Stop it!" Donna cried, tears rolling down her cheeks as she watched the Doctor writhe in pain, his very soul ripping out of his body.

But then, inexplicably, the light started to flicker off, like the energy was dying. The spotlight darted around, unable to focus: something was wrong.

The Doctor opened his eyes.

He sat up, inhaled deeply, sniffing the air, and smiled brightly at Donna.

"You're alive!" she said.

"Oh, so alive!" said the Doctor. He clambered to his feet, and shouted up the sky. "Enjoying your meal, are you? Come on, oh Immortal One! You've been talking all day—why stop now?"

"What's happening?" asked Donna as the light vanished. "I thought you were dying..."

"And I thought you knew me better than that! It takes a lot more than that to kill me. I mean, yes, my spirit was broken. Well, maybe not broken, but definitely cracking. This is a nightmare that's been tailor-made for me. And it worked! My mind was open, my soul was there for the taking and, with it, my regenerations and as close to immortality as you can get. But when the spirit in the sky gorged itself on my spirit, it found more than it bargained for—my thoughts!"

The voice of the Immortal One that had been silent for a while now began to cry out in pain. It was a deep, terrible, booming howl of horror. It chilled Donna to her very core—it was one of the worst noises she had ever heard.

"To steal my future, he had to endure my past! Because in my head," said the Doctor, tapping the side of his skull, "are all my memories, my experiences, all the horrors of the universe that I've seen—and it's a bit too much for you, is it? Give you indigestion, did it?"

The disembodied scream continued.

Then, the perfect world that surrounded then began to fall apart—literally. The ground started to shake and the sky physically fell down towards them.

"He can't maintain the illusion!" said the Doctor. "Quick—into the TARDIS!"

The time-travellers hurried into the police box as the cruel entity died along with his dimension. The scream of the dying spirit was drowned out by the wheeze of the TARDIS engines as it dematerialised, leaving the Immortal One's dimension and returning to the real world.

"Done!" said the Doctor, as he pressed a final button on the Watchtower's main control console. "I've changed the outgoing transmission, telling anyone that hears it that the space station's been compromised. The Human Foundation can tidy this up—and when they arrive, our poor, unfortunate Ood friend who just couldn't catch a break today can explain everything that happened."

The Ood, who had recovered and was once again ready and more than willing to do anything to help, had been given the grim task of carrying all the bodies of the deceased soldiers and scientists to one part of the space station. Seeing this, Donna was reminded that, however happy she was to be alive and despite having defeated the villainous Immortal One from another dimension, not everyone had won.

People had died—nothing could change that.

She looked back up at the Doctor, who was smiling at her. He couldn't be truly happy, Donna knew, with no such sadness all around, but there was nothing else that he could say or do.

The Ood crossed the room to join the Doctor and Donna. It looked at them expectantly, and seemed almost helpless. Donna had never felt so sorry for an Ood than she did that day. The Doctor, however, seemed eager to leave. The TARDIS was waiting for them at the far side of the room, and the Doctor had been looking over to it every few minutes.

"If you don't mind," said the Doctor to the Ood, "we're going to get a move on. Things here are a little too messy for my liking. Too much paperwork involved."

The Ood, agreeable as always, nodded calmly.

"The song of the DoctorDonna continues forever more," it said serenely.

"Oh, I hope so," said the Doctor, grinning at Donna. She smiled back.

The Ood, however, had more to say. "But what of the lost girl with a crack in her wall? Only once the noble sacrifice is made can you rise, victorious."

Donna looked at the Doctor, noticing how unsettled he was by the Ood's comments.

"What does that mean?" he asked, his eyes fixed on the Ood.

"We do not ask questions, Doctor. We simply listen to a higher wisdom, and obey."

"Well, you might want to think about changing that," Donna said. "Or be more choosy about who you listen to. I mean, you were possessed by two different beings in the same day—that can't have been fun for you."

"We are bred to serve. We know no other life."

Donna stepped forward and took the Ood's hand in hers. It cocked its head, studying her, as if curious as to why she was showing a simple servant such kindness.

"One day," she said warmly, "that will change. Trust me. And you'll be able to go home, and be with your people, and sing in the snow of your own world."

The Ood's eyes widened, and Donna smiled. After this mad, terrible experience she might just have brightened the creature's day slightly by giving it the gift of hope.

"He is not forsaken."

"That's right," Donna told the Ood gently as they were preparing to leave. "We won't forget you. Will we, Doctor?"

But the Doctor didn't answer. He stayed silent as they walked over to the TARDIS. As they stood in front of the big blue box, the Doctor seemed troubled, still reeling from the Ood's cryptic clues about his future.

"Doctor, are you okay?" Donna asked, snapping him out of his trance-like contemplation.

"Yes! Of course, I'm fine!" he said, far too brightly for Donna's liking. "Shall we get going? We've still got that holiday booked, remember?"

She didn't answer—there was something else on her mind.

"What's up?" the Doctor asked.

"Just a few questions, that's all. No, don't roll your eyes. They're sensible, honestly. I was thinking... You were bluffing, yeah? Back there in the other dimension, when it looked like the Immortal One had broken your spirit, you were fine all along, weren't you?"

"What? Course I was. Bluffing the whole time."

Donna pursed her lips, not entirely believing him. His pain had been real enough, hadn't it? "I knew it couldn't really have been your personal Hell. I mean, the universe was happy... You wouldn't begrudge it that for your own reasons, would you? Just so you've got a place in it, to keep saving the day? I refuse to believe you're that, well, selfish."

The Doctor coloured a bit in the cheek at the word 'selfish,' then smiled. "It was the only way to win, to open myself up and let that Not-So-Great Intelligence see the truth—that being me isn't actually so great after all."

But the Doctor's reassuring smile vanished instantly as he looked away, unnerving Donna slightly.

"And about that," she went on. "All those things you were saying, about your mind, about all the horrors you've seen—is it really that bad?"

"I've seen terrible things, Donna. I've watched civilisations fall and be consumed by fire. I've stood on worlds as they've collapsed around me. I've seen a star expand and engulf an entire galaxy, purging it of all life. And actually, I've caused most of that stuff myself. That's my life. Doesn't it sound awful when you say it like that? That's enough to give anyone a headache," he said, words drifting away. "But there's good stuff, too—like me and you."

"Shut up!" she said with a smile.

"I'm serious! Days like these, with my best friend, in time and space..." He looked at Donna, right into her eyes, deep into her soul, and smiled that disarming smile she loved so much.

"This," the Doctor said, "is what I live for."