Disclaimer: I so obviously don't own the Doctor or Donna.

In my hearts

He couldn't remember all the details of what happened, just snippets, pieces of his long-long awaited reunion with his bright, shining girl, his joire-de-vie angel with the dazzling smile.

And it being cruelly cut short.

Running, running, running.

Almost there.

Finally.

Flash.

Falling.

Hi.

Long time no see.

Yeah. Been busy y'know.

Once he was back inside the TARDIS, he could feel it starting. It was all but inevitable. Timing could have been better of course.

I mean, for pity's sake, after how many years of waiting, she finally comes back and this has to happen?

He remembered that much.

Which made they way he was feeling right now all the more curious.

He looked across at a distraught Rose, tears streaming down her face.

There was a part of him that wanted to be just as upset, that knew it should be just as upset.

But for some reason he wasn't.

He was …distracted.

His eyes turned to Donna, frantic, apoplectic, almost, desperately trying to get someone, anyone, to tell her what was going on.

Of course she had no idea, this would be the first time she would see this.

And then he was pulled up suddenly by a startlingly incongruous and surprising thought.

This might be the last time you, the current you, you you, will ever see her.

He wondered why that particular thought occupied more time and synapse space in his brain than any other.

And why it scared the hell out of him.

He ran out of time to work through that line of thinking as he felt the regeneration energy surge through his body, bright flashes of light shooting out of every extremity.

He collapsed to the TARDIS floor.

As he came to, his companions' faces told him everything he needed to know: he was okay. He was still him.

Which meant he was still not ginger. Damn.

You..you're still you?

I'm still me.

Rose looked so relieved, and hugged him tight.

Still a little unsteady and emotional, he hugged her back, but there was a niggling sense that something was missing this time – the spark? The connection? Was it because some little voice inside kept whispering I wish I was hugging someone else right now? as he glanced over at Donna and Jack.

Even as he kept his arms wrapped around Rose, he squeezed his eyes shut, as if it might push those thoughts – those traitorous thoughts – away. After all, hadn't he been waiting all this time for Rose? Hadn't she, in all her girlish impetuousness, travelled across all of time just for him?

But his smile, the joy he was supposed to be feeling, it hadn't come as effortlessly as he would have expected. Hadn't had to force it, but it hadn't been as natural as breathing or eating or …. sleeping.

Donna. Even with Rose right here, batting her eyelashes at him, lips all pink and flushed and God, I want you, his mind was thinking of warm, ample curves, gentle fingers smoothing his face, searing lips on a bare shoulder. He hoped Rose couldn't detect the rapid acceleration of his heartbeats. He hoped even more she wouldn't misinterpret them as being for her.

Guilt weighing too heavy to remain with them right then, he excused himself with a bright and jaunty air, ostensibly to go off to the library to do some "critical last-minute Dalek-related research".

Sensing her master's inner turmoil, the TARDIS helpfully dimmed her lights and started to emanate a relaxing, almost hypnotic hum to encourage the others to retire to their rooms, before opening up a door in the library that led directly back to his own room.

He lay on his back in the darkness, eyes wide open, wondering how it was possible to feel simultaneously guilty about his current companion and his just-returned one, and exactly when he had lost the comforting clarity that he'd been unconsciously holding on to for so long.

I am glad Rose is back. I am.

Then why does it feel so hollow?

And why do I feel like I've kicked my best friend in the guts?

Because I guess that's what I just did.

After everything that had been building between him and Donna, after she had finally, finally started to open her heart to him, to trust him, he had gone and trodden all over it with his unthinking impulsiveness. Donna probably thought he had no need for her now that Rose was back, that he was going to dump her, back in Chiswick, back in her old life, promises of forever and always casually cast aside, the best friend eclipsed by the clichéd epic of torn apart lovers and their never-made declarations.

Maybe there was a reason that time ran out, that I never said it.

He sighed, rubbing his forehead. The TARDIS hummed softly, illuminating a far wall and a door he didn't recall being there before.

What are you playing at, old girl?

Maybe his ship, his sensitive, temperamental but incredibly insightful ship, could help him find some answers. Or at least the way forward.

He got up from the bed and walked towards the door.

In retrospect, he shouldn't have been surprised in the slightest that the TARDIS had moved his room right next to Donna's and so the door led straight into her room.

She was lying still on the bed, but her face was turned away, so he couldn't tell if she was sleeping or not. Out of the corner of his eye, he noticed in the far corner an open suitcase, with neatly folded clothes piled inside and his heart fairly cleft in sorrow. She really thought he would make her leave.

Regret at his earlier careless exuberance over Rose and the irony of its emptiness having the power to render his beloved best friend suddenly anxious and afraid of the future and doubting her worth and her place with him, weighed heavier with each step he took towards her.

He had to fix this.

This was not worth losing his best friend over. Nothing and no-one was worth that., to face his past, his present and his future, what that all meant, what he wanted it to be and who he wanted it to be with,

Armed with renewed courage, he quietly and purposefully moved to the foot of the bed and crawled up to where Donna lay.

She stirred then, and the look of utter shock and astonishment on her face that he was actually here with her made his hearts sink. He had let her down badly.

He feared that any attempt to speak right now would end up being too wordy and incomprehensible and nowhere near adequate in either reassuring her or explaining himself.

So he did the only thing that he thought would.

He kissed her. Long and hard and with every ounce of love he had in him, because he realised, now, that it belonged to her anyway.

He tasted her tears and his lips moved to take each one away. In between kisses, he tried to salve her cut and weeping heart with I'm sorry…still love her but….can't lose you…TARDIS knows…you're beautiful….need you.

Tears of his own threatened as she plaintively, achingly asked him why he was even here at all.

He had to repair the damage he had done, help her get back to where she belonged, to a place where she knew she was special and wonderful and loved.

Most loved.

So he spoke again, more firmly, resolutely this time.

You are enough.

Enough for me.

Just by being you.

I will never leave you.

He moved her hand over his hearts and looked into her eyes, sealing the promises.

You're in here.

Deep in here.

Forever a part of me.

My hearts beat for you.

And they leapt in joy as he saw the happiness, the confidence, the life that was uniquely her flare anew, even grow stronger as he reaffirmed his desire for a future with her.

It wasn't important how or when he told Rose. What mattered was the woman in his arms, his best friend, his lover, his life, and that she knew all that.

And when he'd finished telling her in words, he told her again with his body.

Over and over until she believed.