I walk as though the sun is in my hands; yet live as though the earth is frozen over, and I can see nothing but the whirling white. My steps are steady and rhythmic, like the crashing of a wave, and yet I falter with every movement and my legs bend, my muscles shaking as though they have no substance. Tears tremble down my cheeks. They burn like fire, and yet I am colder than anyone could ever imagine, like a shard of ice rests in my soul. I walk with the terrible solemnity of one who will die if they stop, and whither away to nothing.

I walk as though I'm dead.

I'm shaken by nothing. When mum calls – and it's terribly often – it takes her a few tries to snap me back to reality. Cold, hot, evil reality. When I wake up in the morning, tears stain my cheeks, and it takes several sickening seconds to remember why. He's gone. He's gone forever.

It's not the type of thing that you can just shove to the back of your mind and forget about, like a bad dream or even the death of a relative: it's like he was ripped from my life, literally torn from my hands. In those seconds when my fingertips lost hold and I went flying toward the Void, feeling its tug wrapping around me like deadly, tender, loving fingers, my only regret was that I would leave him like that, with that mind-crippling expression on his face. And then the next seconds were even more bitter: I didn't know how to comprehend the situation as Pete suddenly materialized, and his strong arm wrapped around my middle, and we disappeared. His expression had changed in that moment as well. I'll never forget it... and yet I can't describe it.

It was an evil mercy when I realized it wasn't over. The dreams, his gentle whispers, beating around my head: Rose. And then to Bad Wolf Bay we flew, and I saw his face once more. All sad and strange and mad as he watched me across dimensions, gazing at me with eyes that seemed to say he was the one trapped in the wrong universe, not me. I might have reached out in that moment, just to see for certain that he wasn't a hologram, but I was too afraid that it might break the link. No part of my mind would let me risk it. It had been cold, on that beach in Norway, but as I stared at his face I was filled with a burning unlike any other. I knew that those precious minutes would be our last, but I couldn't think of a thing to say. And then of course he disappeared, and all the questions and comments I'd wanted to make came slamming into my head like a freight train. But then there was nothing to be done about it; he was gone, gone forever.

I was boiling with anger and freezing with pain, and there was nothing to say; no feeling in my limbs as Jackie wrapped her arms around me and guided me back to the car. As we walked, the sun freezing in my hands, all I could think about was that little thing – your mother's arms around you. You never notice the little things when you're with him; they're not important. But now they were all I had.

That winter was the coldest I've had since returning to this universe, and that summer the hottest. I think I wrote letters to him, but half the time I can't remember. The whole year was a blur of quietly sitting through family meals, passing empty smiles to neighbors as they walked by, and beating my fists into the wall of my bedroom when no one was around until the skin chafed away and faint pink stains appeared in the plaster, messy reminders that I never bothered to try and wash off. I remember sitting awake endlessly for nights, feeling the wonderful memories prick at my consciousness and trying to push them back, only to give up when my efforts were washed down my cheeks alongside my tears. My heart became frozen, despite the fire that the crying created.

The first month, I think, was tough on my mum. She sat patiently through my silence and periods when we both pretended that I wasn't trying to not cry, because she knew I needed time. But I wasn't done, not even after that. I couldn't be done, I missed him so badly. The next month was filled with passive comments: Maybe you ought to be getting a job. If you save up, you might be able to get that place on the other side of the street. There's some great places in town where you could work. You haven't been out of the house in ages.

I would sit and listen, but never fully register them. As time passed, she gradually became more persistent, and then hard on me – forcing me out of the house to go for a walk, saying it would do me good. I did it, of course, but there was no joy or relish in any task she set to me. And all the while I was aware of the sad, pitying expressions she shot me when she thought I wasn't looking.

I went between burning and freezing each night as I struggled and failed to sleep. My eyes were afraid to shut; afraid of seeing an image of his face trapped beneath my eyelids. Afraid of having a dream that would shake all the trapped memories to the surface. I became weak and shivery during the day, despite my hot forehead, and often suffered from periods of sleep loss, all of which I did my best to hide from mum. She was always so worried about me, she didn't need more to add to her plate.

I kept thinking if I could be left alone, if I could just get a long enough period to myself, to fight the demons in my mind, then I would get over this. But that time of relief, that moment of reckoning, never came. It was just a constant battle against exhaustion, fear, and the thoughts in my head. I never asked for help, however. Maybe I was just stubborn, but the idea of looking for support in any way just crushed me. I felt that if I couldn't get over him on my own, then I was never worth the Doctor's attention anyway.

There were many quiet weeks spent crawling through my basic functions, purely out of habit than any drive to get things done. Do laundry, keep the house organized, maybe eat something on occasion. I never noticed anything I did, though. They were just actions; just mindless things, with no thought put into them. All of my thoughts were with him, with my Doctor.

I was beyond the expressions of longing, or missing him. It was just an endless ache; a raw, undiluted burning within me, more painful and horrendous than anything else, and yet unable to melt my frozen soul. Every part of me throbbed with sadness and... despair. Just despair. The despair of knowing there was nothing I could do to change things.

One day, deep into this period of regret, I came across a discarded pair of black jeans as I was cleaning the house. Several seconds of staring identified them as the pair I'd been wearing at Canary Wharf. A dark throb started in my temples, but it wasn't strong. The whole event felt like ages ago. Carefully, as though they contained a bomb, I dug around in the pockets of the jeans and produced a handful of old pictures. I barely had to look at them to remember what they were from. The last place we'd visit before Canary Wharf had been some old, long-forgotten town in the 1950's, where we'd walked along a wooden pier in the balmy air and I'd listened as he told me all sorts of mad stories that half the time didn't seem to be possible. We were laughing, half-waltzing and half-staggering as we walked, and a tired, elderly man with a Polaroid camera had offered to take some pictures. There was no real reason to say no, and we'd posed as ridiculously as possible, gripping each other as though if we let go the world would implode, and laughing like there was nothing better to do. The cameraman had been mystified by us and our joy – maybe that's why he'd offered in the first place.

I flicked through them carefully – they'd seemed to have suffered some water damage since the Doctor had told me to keep them safe and I'd quickly shoved them in my back pocket. The pictures seemed to have gotten a bit filmy and hazy, but the images were still clear and it was several long seconds before I realized I was smiling.

There was a bitter moment as I sat there during which I almost forced the smile from my face, more out of spite than anything else. But as I gazed down at those pictures; at his grinning, aloof face, I couldn't bring myself to do it. There was something deep and tender about seeing him frozen in time like that, trapped in perfection beneath a camera lens. Something bittersweet about old-fashioned Polaroid and camera shutters clicking images into existence, creating memories of things that shouldn't even be real. Something a bit mad about staring at this pile of photography and knowing that every single second belonged to a completely different universe.

It occurred to me then that these precious pictures could fade away into pale, filmy nonexistence and the idea scared me so badly that I was on my feet in an instant, dashing to my room, moving faster than I had in months. I found an old, thin gray box among the clutter of the shelves, wrapped a tissue along the bottom and then ran to the kitchen. I slipped the photos into a plastic bag and placed them gently onto the tissue, carefully clicking it shut. I walked slowly back to my room and sat on my bed, holding the box in front of me as though it contained a bomb. For several seconds I sat there on the edge of my sheets, not knowing what to feel, and then quickly popped the lid open again, freed the pictures, and went back to flicking through them.

Memories. They're silly things, really. Flickers of what had once been a reality, now reduced to nothing but a dream, or rather a fragment of that. Something that seems to escape reality as though it never happened and the only thing to keep them in your head is your own conviction of their existence. Never was, never will be, never might have been – the Doctor had tried to teach me past-, present-, and future-tense during time travel, during one quiet night in the TARDIS. I wondered if I still had it right.

A freezing fire of hope had started in my heart, and I went into the other room, retrieving the pair of jeans, praying that they might hold other treasures. When I'd crossed universes, I'd had nothing with me. None of my clothes I'd left on the TARDIS; none of my suitcases, journals, pictures or souvenirs; nothing at all that I'd had back at home. I wonder what the Doctor had done with them, if anything. But now here was the small chance that I might have kept some of it with me, completely by chance.

My prayers were rewarded – a long, old string of film fell from one of my pockets and into my palms. I stared at it, stunned, for several seconds, because I quite simply had no idea what it was. I didn't remember having anything to do with it, let alone recording on it when I'd been with the Doctor back in the 1950's. But if there was one thing I was certain of, it was that I had to know what was on it.

This universe ran a few years ahead of the other one, which made it all the harder to get our hands on an old projector that was built for this film, but the moment my mum saw how alive I became as I began the search, she was instantly at my side, helping. Limitations of money or distance didn't matter – whatever would make me my old self again. Many times I felt awful for how I'd taken advantage of her, but looking back on it, there was no way I could live without seeing what was on that precious pile of film.

We finally got our hands on a fragile projector from who knows how long ago, and it took every ounce of my patience, self-control and sensibility to keep myself from breaking it when I first pulled it out of its cardboard box, adorned with packing peanuts. I took it carefully to my room, and cleared a wall to project the film – our sender, who we'd finally found on E-Bay, was nice enough to include instructions.

Once the film reel was wound and the projector was ready, I nervously pressed play.

After a few shaky, flickering moments, the Doctor's face jumped to life on my wall, half-grinning, with his glasses pressed gently onto the tip of his nose. My breath caught at his appearance, and I bit my lip nervously. It was such a throwback: for a moment, I could be in the TARDIS again, standing with my hands in my pockets next to the console. I could just see his trenchcoat drenched over a chair in the background.

"Hello, Rose!" He beamed. "I'm going to slip this in a pair of your jeans the moment I get a chance, so if you're watching this, I'm certain you're a bit confused. I thought I might send you a message. I'm with you in 1953 right now, somewhere outside of London. Charming old town. Remember when we did that? Well, that man with the camera inspired me, and to be honest I love operating old machinery. So clever, you humans, coming up with something like this. Cheap materials; you're barely even capable of freezing things, and yet you make do, carry on, force it to work no matter what. Ingenious, this film!

"Anyways, if you're watching this from the projector on floor 25 of the TARDIS, then clever you; I knew you'd find it. If not, well… I'm sure it's been awhile, if you had enough spare time to figure out this puzzle. Hi again. Now I'm sure you're getting all mad and huffy, if you're on your own, but I guess that's another part of this message – knock it off! I'm sure you're having a lovely life, with Jackie and whoever. But forget that, what I really wanted to say.

"It's occurred to me lately, what with us seeing Sarah Jane and all, that I wouldn't want to leave you – because I have to someday, so no whining – with no message or anything to remember me by. And of course you had to get some boy from this decade trailing you left and right and begging that you let him take you to dinner, so I figured I'd take advantage of the free time. Give Rose Tyler a message; she deserves it.

"Alright then, here's the message: Don't sit around in your house, moping about like I know you will, and pretend like there's nothing left in the universe for you. Go; do something brilliant. I know you can. Go be the brilliant Rose Tyler that you are when you're aboard the TARDIS, cracking jokes and laughing in the face of danger."

I heard a muffled thump somewhere in the background and the Doctor looked up accordingly, his features sharp and angular as he glared down what could be some unknown danger. That simple little thing of his that I knew so well. I swallowed.

"I think that's you," he turned back to the camera, his voice a hiss. "And I suppose it's my cue to go. Well anyway, have a nice life, do what you need to. Oh-! And if you got a hold of this before you've left the TARDIS, well… save it for a rainy day. Alright," he smirked, leaning close. "Bye now."

The image froze, flickered a bit, and then shuddered out of existence. My room was swallowed into darkness and for a long time all I did was stand there and stare and my empty wall. After awhile I moved to my feet, pushed back the film, and played it again. And then again. I didn't dare go for a fourth time – although I wanted to – for fear of overworking the ancient machine. But of course the film itself felt new in my palms – it had barely existed over a year. I felt like I should be mad at him; haunting me with his face like that, but I wasn't. He'd given me a gift. Now there would never be any fear of forgetting the sound of his voice.

The words of his message echoed in my head for the next few days, making me freeze and burn, back and forth, aching with indecision. I watched it again a few times, but of course felt unfulfilled. The idea of completing his request made my head reel a bit – I'd unfortunately entered the pattern of doing nothing and hating my life, exactly what he'd wanted me not to do. I was occasionally filled with the image of him pacing the TARDIS, wondering if that pair of jeans I'd been wearing was the right one. It made my head throb.

And then came UNIT.

"The stars are going out," Commander Joanna S. Linden had told me. "And you know the Doctor. You have to reach him for us, because it's not just our universe. It's all of them."

I wasn't enjoying the task, not at first, and neither was my mum. She thought me mad for wanting to get sucked back into all of that alien stuff, and I secretly believed she might be right, but I had to do it. It wasn't very noticeable at the time, but it was true – one by one, the stars were winking out of the sky.

For a long time, it was just testing equipment, and they hardly needed me. I only showed up every day to get used to the schedule and to distract myself from my own dark thoughts. Finally, they were ready to include me into the equation – but things still didn't get better. Then each day was filled with fizzing out of the universe and into another, desperate to get the Doctor's attention. Most of the time I'd just get a blurry view of another world, or maybe just the stars, but on a rare occasion I would see the inside of the TARDIS, and once the back of his head. And then of course there was that whole encounter with a woman who wanted me to tell someone something about keys, and the fury that brought. If only I'd known at the time that she was Donna Noble, we could have stopped all this.

Things weren't going to work out that way, however. One day Linden came to me, her expression dark and grim. "Plans have changed, Tyler. Circumstances have become a bit more… dire. You won't be going to the same universe, not anymore. A parallel world has been generated because of the existence of one woman… and the Doctor's about to die there. You must try to stop it."

I failed, and bitterly at that. The goal changed once again – now I had to convince Donna Noble to kill herself, in order to save the universe. I hated every second of it, but I kept telling myself that one step closer to success was one step closer to the Doctor. It was the only way. With each teleport, each step in this fake universe, I learned more about her and came to respect her. I resented my job with every word I spoke, and it was only worse that she didn't seem to hate me for it. She was just scared. But she never once blamed me.

Finally, the moment of truth came. She slipped back in time through the feeble time travel device we'd made using the TARDIS, and I followed her. Followed her to complete the simple task of passing the word to the Doctor, with two simple words: Bad Wolf.

And now we're here.

Linden gave me another of her sad gazes, as though she felt like she'd corrupted me. I doubted it: any influence aliens had on me was entirely the fault of my Timelord. She was just another pawn in an endless game; a game that wouldn't stop even when you were a universe away from the action. But that was beyond the point now – the Doctor needed me. That's all that matters.

"The universe Donna created no longer exists; good job," she said. "And if things have gone to plan, then the Doctor got the message. He knows to get to Earth. Now, we need to get you there. From what I understand, your warning didn't exactly explain the whole message. What did you say to Donna, anyway?"

"It's a long story, you wouldn't understand," I mumbled quietly.

She half-shook her head, sighing. "Fair enough. Are you ready?"

I swallowed, and adjusted my grip on the gun they'd given me. High-tech, Linden had said, and one of a kind. Nothing else like it among any of the other weaponry UNIT had salvaged. I was amazed that they'd trusted me with it, considering I wasn't a legitimate member of UNIT, just a guest. Just another chess piece in the endless game. Still, I figured I'd done them enough miracles to earn a decent weapon. "Yeah, I'm ready."

She gave me a terse nod. "Right. Fire up the hyperlink."

A soft, heavy whirring began around the arc-shaped, metal ring I was standing in. Energy flared in blue light along the edges. I stood straight, slowing my breathing, trying to prepare myself for something I didn't know how to prepare for.

Linden gave me a look, glancing away from the workers who – quite literally at the moment – had my life in their hands. "We've already damaged the time space continuum enough as it is. There's no chance that we'll be able to get you back once this is over."

"I know," I said, and was suddenly terrified. "My mum doesn't know I'm here. If I told her, she wouldn't have let me do it." An image entered my head of her flaring through the high-security base to this room and demanding to see her daughter. My worries were quelled, considering that was probably what she was doing. "She... has a teleporting device. Sort of yellow, and round, with a metal rim. Do you think you could-"

"Supersede the hyperlink to re-activate the mechanism?" She frowned. "Yes, probably. But I'll most likely get fired for it."

I made to reply, but she stopped me with a grin. "...and I don't mind, for the record. If your mum can even get into this room – and I'll believe it if you do – then she's certainly certified to be jumping dimensions."

I smiled. The humming had gotten louder, and more intense. My stomach flipped nervously and I found myself at a loss for words. The chance of me seeing this woman – any of these people – was terribly low. I wouldn't see this sky, the street, my room. I told myself that didn't matter – none of it had ever really belonged to me anyway. Just things, just objects that I saw each day, and each day reminded me that I was further from him than I could ever be.

"Ten. Nine. Eight," Linden began to count as she walked back to the control panels, shooting me one last knowing look. I looked away from her and closed my eyes, hoping the teleporter wouldn't hurt. I wasn't even too sure if they'd tested the thing. If I died, well... It was worth it, I think. Nothing better to do around here. The Doctor told me to do something with my life, so... why not save all of creation? Seems like a worthy task to me.

"Five. Four..."

I closed my fingers around the gun, nearly crushing it out of nervousness, but that didn't matter. There was no going back now, and even if I could, I wouldn't. What was there to go back to? Endless nights of sitting awake and cursing the universe, praying for escape, for a way out? No; this was my destiny. To find the Doctor again... Oh, how I missed him.

"Two. Good luck, Rose Tyler. One."

I was surrounded by a brilliant blue light that encased me and cut off my view from the world. For a moment everything was blue, and every inch of my body prickled with a fiery heat and an icy cold. There was no way to describe it as I left the universe and floated for a few seconds in limbo, not in the Void, or any universe: barely even in existence. And then the burning-cold blue was back, making my eyes ache, and after a few seconds fading, to reveal the earth again.

But a different earth; the old one.

Maybe it was the after effects of the teleporter, but in that moment my body flashed between burning and freezing and I didn't know what to think or feel. A shiver ran up my spine as my head whirled and my feet began to feel the ground once again. My fingertips dug into the firm metal of the gun between my hands as the world came back into focus.

I'd done it now.

I walk with the sun in my hands, and yet shiver as though trapped within an endless blizzard. My skin is cold, but beneath it I am on fire, running out of fear of the enemies in my head and the terrors that hide in my shadow. I am like a forest, consumed in a frozen flame, engulfed in a blaze of pain, loss, and raw determination. The universe – all of them – are as cold as they are hot, and sometimes at the same time. Sometimes, you feel it, that balance, and it's scary. It's scary to know that I can be just as deadly and dangerous as a troop of Daleks or an angry Timelord. It burns, that power. It burns like ice.

The sun, I must say, is very cold.