Nothing is ever as simple as it was over six years ago, when naive and nineteen she had stepped over the threshold of the TARDIS and believed the Doctor's mastery of time and space would enable her to return to the precise moment she had left; that no one would be any the wiser to her fabulous journey and that she could put off uncomfortable goodbyes and tedious details to some wonderfully vague future. At twenty-six, with the kind of job she has, a family she still eats dinner with on a Sunday... there are things that need to be done before she starts travelling again. Not least packing some clean underwear, something that somewhat regrettably hadn't entered her head last time the...a Doctor... had made this offer.

Fortunately, the TARDIS was in no shape to fly anywhere, and she left the Doctor tinkering to deal with the mundane preparations of leaving. Micked was outside the TARDIS, face anxious. A security team, flicking the safeties off their machine guns as she emerged, were ranged behind him. She held up her hands as they raised the barrels of the guns. "It's me," she said simply.

Mickey waved a a scanner, backwards engineered by some of Torchwood's brightest from alien material, at her. "She's clean," he said, and the soldiers lowered their weapons. Rose hardly used the scanner. If the Doctor had taught her one thing, it was never to be over reliant on technology. Why do a scan for alien tech if simply asking a question could suffice? Before breaking out the machine she found asking for a piece of personal information would often be enough to expose the majority of alien duplicates.

"It's not him," she said quietly, "It's this reality's Doctor."

"Why's he here?"

"Accident. Picked up the Auton's signal but hit a week to late. The TARDIS is badly damaged."

Mickey saw her expression and knew better than to ask why. "So he'll stay until he fixes his ship... then what?" His face fell before she even opened her mouth. They had never rekindled their relationship, in spite of their closeness. Privately, Rose had felt Mickey deserved better than second place, better than a lifetime of knowing that if she could have been with the Doctor instead she would have been.

And the days were long gone when Mickey was happy to settle for second place.

Nevertheless, she knew he still cared deeply for her, as she him. He could read her answer in her eyes, knowing her so well. "You're going with him, aren't you?"

She nodded.

He was silent for a moment, face grave. Then he nodded. "I'm glad."

"Really?"

"Yeah. I mean, it'll be hard for your mum and Pete, and Olly's really going to miss you... but..."

He left the sentence hanging and she found a lump had risen to her throat at the thought of her family. "Thanks," she managed.

"You're going to tell them?" he checked, and she rolled her eyes in response.

"Of course. This isn't like last time. I'm tying up my loose ends here before I go swanning off."

"Does that mean... we'll never see you?" he asked, eyes widening.

She laughed. "I doubt it. It's not as if he didn't let me visit last time... I mean, the other Doctor. They don't seem all that different. I just..." This time, it was her that couldn't quite put her feelings into words, but Mickey thought perhaps he understood.

Rose would never, given the chance, have left the Doctor. In their own reality she had always left enough of herself behind on Earth... in a messy bedroom that went untouched by Jackie in her absence, in the lie that she was 'travelling' rather than gone for good, in the friendships she half maintained with the occasional text message : "Jst been 2 Rome (never mind it was 3rd century Italy, and she'd been wearing a toga) weather's g8!" ... enough of herself that there was still the implication that one day she'd be back for good. He knew that this time, she didn't want that. If she did come home, she'd build herself a new life. She wouldn't want to simply pick up the threads of her old.

Rose has almost finished cramming the last of her packing into the rucksack when she felt the key around her neck pulse with warmth, and the curious whooshing noise of the TARDIS materialising filled her bedroom. She stood stock still, pair of socks still in hand as the outline appeared, filled out and the blue box was standing, impossibly, in front of the window.

The door swung inwards, and the Doctor was leaning against the lintel. His eyes bulged slightly as he took in the suitcase and huge rucksack.

"Before you say anything," she said acerbically, hefting the rucksack onto her shoulders, "I know that the TARDIS is potentially infinite in size. And also that travelling with you takes its toll on clothes, 'specially shoes."

He grinned, apparently proud of this and stepped aside to let her on board.

She stopped in the centre of the console room, taking a deep, happy breath. It looked exactly like she remembered, even down to the rubber mallet the doctor was so fond of whacking the console with in times of mechanical crisis. She tried to remind herself that this wasn't home, that she'd only been inside this TARDIS once before... but perhaps that was wrong. This was home now; and she'd be lying if she pretended that she didn't hope it always would be.

She was mildly surprised that the room the TARDIS selected as hers was different from last time. She went to the same door as last time, the closest one to the console room and opposite the kitchen (or one of them, at least). The old TARDIS had often rearranged her rooms, putting them behind different doors, but somehow she'd expected the machine to present her with the same bedroom. The Doctor had never said as much, but after learning the TARDIS was inside her very brain she'd half suspected the wily old time-ship selected the rooms for companions based on their needs, maybe even created them to suit.

Last time she'd flown inside a TARDIS, to all extents a clone of this one, the room she had been presented with had been roughly double the size of her room at home, decorated in a light pink colour, with matching bedclothes and a huge mirrored wardrobe.

This room in comparison was more neutral in colour, the walls the same unearthly material as last time but a light cream colour. There was a four-poster double bed apparently carved from a dark wood, the bed clothes blue, with patterns picked out in silver thread. The furnishings; a wardrobe, chest of drawers, desk and chair and free-standing mirror; were the same dark wood as the bed, the carvings adorning their surfaces matching.

There was another door opposite the entrance. Turning the knob, it opened into a bathroom, again different from the one she remembered. She wondered what all these differences meant; were they reflections of the changes six years had wrought on Rose Tyler? On balance, she decided these were the rooms of a woman, rather than those of a girl on the verge of becoming one. She grinned at the thought of her nineteen year old self's reaction to that statement.

The Doctor was standing by the control panel when she emerged a few moments later. Too excited at the prospect of adventure to unpack just yet she had simply dumped her bags. "Where're we going?" she asked, unable to keep the grin off her face.

He smiled back at her. "I thought a secret underground bunker near Salt Lake City, Utah, might be a good place to start."

She nodded, realising he'd had the good grace to only look at her memories regarding her time with the Doctor. For a moment she considered letting him go, and find out for himself, before smugly filling him in on the details. But that wasn't really Rose's way.

"Henry Van Statten died in a car crash in 2008 in this reality. The bunker's been filled in and Torchwood took his collection of alien artefacts." And put Adam to work on one of our research projects, she added mentally. "The Dalek was one of two items I remembered never recovered."

The Doctor's smile broadened.

"Victor Kennedy doesn't exist here either," Rose went on, "And Chloe Webber... her Dad was arrested on domestic abuse charges after a passing police officer made a house-call one evening. Trish and Chloe got counselling from one of the best, and live in Manchester now. And a Torchwood team was waiting in Dame Kelly Holmes close for when the Isoles pod arrived, and sent it back to its family. The Slitheen haven't turned up yet, nor the Sycorax. Perhaps they never will. But Torchwood is ready and waiting all the same."

There was admiration in the Doctor's eyes, but he did his best to hide it. "Seems like you thought of everything," he said grudgingly.

"Nah. That's your job."

"Well since the Earth seems in no immediate great danger... where to Rose Tyler?"

She thought for a moment of all the places in a thousand galaxies she'd seen, all the words she'd whizzed past on their whistle stop tour of the universe, all the things she'd yearned to see just one more time... His question felt like a test, but this was one she thought she knew the answer to.

"Somewhere new."

The quirk of his eyebrow let her know she'd answered correctly. "Here we go then."

He pulled the lever and with a tremendous jolt the TARDIS launched itself into time and space once again.