A/N: This is my first ever foray into the world of Doctor Who fanfiction, so be kind to me. I like happy endings and I love Rose Tyler, just like the Doctor does. If you agree with the above statements, I think you'll like this fic. ;-) I would love reviews!

As It Must Be

Prologue

It all started with the TARDIS.

Rose always knew that the TARDIS was sentient. It was clear from the waves of emotion she'd always felt from her, from the moment she stepped on board the first time. She had always, if perhaps inexplicably, felt for the TARDIS like an old friend.

It hadn't surprised her in the least when she'd found a room for herself in the perfect shade of pink. Or when her favorite breakfast foods were laid out for her in the kitchen in the morning. Or when she had stepped into the wardrobe room for the first time and the racks spun until they settled on the perfect dress in exactly her size for Cardiff in the 1860s.

The Doctor, on the other hand, was more than slightly confused by these developments. Brow furrowed, he would just mutter to himself, "Must be overjoyed to have someone other than cranky old me on board."

It got increasingly strange after the Bad Wolf incident. The memories from that time were slow to filter back and even when she thought she might remember, they seemed more like blur of light and knowledge beyond her comprehension than anything coherent.

But when confronted by the world in need of saving and no Doctor, she could have sworn she actually heard the TARDIS say, Here, to me. And she had this awareness of where they were when she stepped out of the TARDIS onto the Sycorax ship which the Doctor always had and which he had tried to explain to her before. A kind of knowing.

And it just kept right on like that. The TARDIS was like a golden presence in her mind constantly giving emotion, speaking, explaining, sharing knowledge, and assisting her directly when the Doctor was poisoned, knocked out, or captured by alien prisons.

The Doctor noticed, of course, but it couldn't be true. Humans simply didn't have the kind of telepathy that she was displaying.

She brushed it off. The TARDIS was just getting to know her better, bonding with her. Surely it had done so with the other companions as well. And anyway, it was all only helpful.

Then there was that time when the TARDIS was lost on the impossible planet and it hurt, was wrenching, more so perhaps even than losing the Doctor to the Isolus. And it hurt in such a similar way. There was the fear of losing a best friend and loved one, but there was also a wrenching stab of emptiness and loss in the back of her mind. She didn't say anything about it to the Doctor. He had enough to deal with already and she must have been making things up.

And now. When he had sent her to the parallel universe without him and without the TARDIS, the pain had been inconceivable. She was not making that up. It was an utter emptiness and isolation that cut and bit and hurt so badly that she felt insane. And then she hit that big yellow button and was back to the proper universe and it was all relieved in an instant. It was all she could do not to jump him when she got back. She wanted to drag him back to the TARDIS and fuck him until he screamed that he would never ever leave her.

She shook herself as he joked and handed her a magnaclamp. What on earth were those thoughts? Dark and possessive and completely inappropriate. The TARDIS, who had been sending her comforting and approving waves of emotion since she made it back to this universe, gave a disapproving snort at this thought.

She shook it off. It wasn't the time to be arguing with the TARDIS.

She clung to the lever minutes later like it was all that was holding her to sanity. Because it was. She was glad, she realized fiercely, that if she slipped off this stupid lever she would be nonexistent. Anything would be better than that horrible aching pain in the other universe.

But then she was falling. Her eyes locked with the Doctors for a long horrible moment and she could suddenly hear him in her head in brilliant, burning clarity, Rose, rose, rose, rose, rose, no no no.

And the words were accompanied by a blast of overwhelming, intense love. And not a friendly love, but one tinged with a possessive passion which almost frightened her. All this in the instant she as was sucked toward the void. And in despair she shoved a response through her stupid human mind, because he was going to be all alone and she had no idea how he could possibly cope with that in this burning instant.

I love you, my Doctor. The words, the emotion, the feel of them visibly rocked him. His eyes went round with shock. And he reached out a tentative, telepathic finger to stroke her mind, obviously forgetting in the shock of this connection that she was falling.

Suddenly someone's arms were around her and she wasn't falling anymore, but standing and plunged into even more pain than the first time she had been here. She let out a cry and crumpled to the ground.

"What?" He whispered it, incapable of full voice.

He was horrified, paralyzed with the shock that he had gotten in the last few minutes. His mind was doing too many things at once for even him to process. There was, overwhelmingly, pain at the loss of Rose. And then a whole host of shock and confusion at how much it hurt to lose Rose. Of course, he could have told you that losing her would hurt, but this!

This was like someone had sliced open his brain, like his essence was seeping out to the floor. And that was because, because … there was something in his mind which he had hidden from himself! He could see it now, had felt it vividly when Rose had tugged on it as she fell, used it to call to him, to send him her emotions. No one should be able to do that anymore! No one but the Time Lords! And even then, that sort of aching, pulling bond, her possessive ferocity, it was as if …

He couldn't process her loss because he was too absorbed in his discovery. He raced back to the TARDIS. You knew! He shouted mentally. She gave the equivalent of a shrug, weak and hurting. Hurting? The TARDIS gasped and pulled away a mental wall she had been keeping up. The Doctor sank to his knees with the rush of awareness. How could, his Rose was, she had … !

He had certainly noticed oddities in the way the TARDIS acted towards Rose, but attributed it all to his ship's joy at having someone, anyone to cheer him and save him from his self-destructive attitudes before she had gotten there. But there was more to it. There was a bond, stemming from the Heart of the TARDIS, but linking and looping through her timeline and his own. He gaped a little. "Rose and I, we aren't, we aren't linear? But how can that be? I would know! I would remember!"

She shoved weakly at his mind, pointing him to a walled off section. Similar to the wall she had just lifted. He was about to rip away this curtain as well when she sent a stinging reproof. Not yet! He groaned, a little ashamed at her reminder. They hadn't linked to linear yet. He couldn't reveal the memories he had apparently hidden from himself.

She'll come back to us. The TARDIS said, slowly regaining strength. But we need to help her. And not cause a paradox along the way. This last was directed scornfully at him.

He raised his hands in supplication. "I know, I'm sorry. Just, help me. What do we do now?"