Had we never lov'd sae kindly, Had we never lov'd sae blindly, Never met - or never parted - we had never been broken-hearted.

-Robert Burns.

Prologue: Left

She missed the light, above all things.

They could only use the dimension cannon under the cover of darkness, not that there was an alternative. The skies had darkened long ago, and moon had been lost in the shroud. The only reprieve were the parallels; the urge to jump and scream with joy when she stepped into Donna's world and looked up at a sky full of stars. A world that still had some morsel of hope; some light.

Quickly squashed under a thick red blanket and carried off on a stretcher.

"What happened? What did they find?"

She ran until she couldn't breathe, following the flash of an ambulance where there should have been a victorious – alive – Doctor.

"I don't know; a bloke called the Doctor or something..."

Doctor, Doctor.

"Well, where is he?"

There is was again; the urge to tear things apart to find him like ripping apart a stack of hay to find a pin. Nothing seemed important enough to her, everything was too expendable, and it worried her to the bone.

"They took him away. He's dead."

It all came back, like she was drowning.

Standing on top of a dark hill, looking down at a world so much further along than theirs, and the streets were on fire; standing in the rain, huddled amongst the panicked crowd waiting to see if he would appear; stepping over bodies lying in the street and knowing without a shadow of a doubt that it was the wrong universe yet again; and then finally; we've got a lock on a TARDIS. We've found it.

This was it; there was only one him. Too late; game over. Everyone dies.

"I'm sorry, did you know him?"

Forever.

"I mean, they didn't say his name – could be any Doctor."

She could've laughed; right there in the street. She could've burst into hysterical giggles until they came and brought a stretcher and a red blanket and took her away too. Perhaps they would put them next to each other in the morgue.

"I came so far," Rose said.

They thought it was the dimension cannon that had pulled her through the cracks, and she had thought it was him. But if he'd died then maybe it was the cannon all along; the love of a cold device. So much for her stupid sentimentality. She had done this for everyone; but for herself too. She could see that now, just how much of her quest was build on the foundation that she would be able to see him again.

They were all fucked.

Rose looked at the woman; red hair and a strong face. Something about her screamed: left, left, left.

Unbidden, and as she spoke, Rose's eyes travelled over the woman's left shoulder. It was like a face, grinning and impossible, taunted her at her back. Something crawled beneath her hair; something wrong.

"What's your name?" Rose demanded.

"Donna, and you?"

Left, left, left, left, left, please, left.

"Oh, I was just passing by; I shouldn't even be here. This is wrong. This is so wrong."

The universe clawed at this one woman; Rose could smell it. She could sense the desperate grip of lives trying to repair themselves through her, and the heavy ghost of the Doctor's absence sang through her. Time folded around her; at her will, and people would die.

A world without the Doctor, and this woman was something. Something new; something important. Something to do with life and death.

"Sorry, what was it; Donna what?"

"Why do you keep looking at my back?" Donna asked, her face hard, and Rose was brought back to reality; back to chips and Saturday nights and football. Back to the loneliest Christmas day she'd ever had.

"I'm not," Rose deflected, averting her eyes.

Left, left, left, important. Go left.

It was his voice now; whispering in her ear. That echo from so long ago, devoid of any life, just that one word, that one direction, and she started to understand. Donna was something important. She was the key they had been searching for, and the Doctor was the door.

No use trying to open the door without the key. Donna was talking again, but everything was so wrong. She was tried. Hungry. Tired.

And so she did it; she did what she hadn't done for months and she gave up, pushed the little metal button stowed in her pocket and blinked out of one universe and into another.

Donna, Donna; she said the name over and over in her head, scared that she would lose it. She didn't have a last name; for months they would work to track her timeline.

Until they knew better, they called her Donna Left.

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