The Difference You Make

Disclaimer: Nothing is mine.
Originally written for a Livejournal challenge with the prompt "jealousy".

--

He sees it every day in the faces of his employees, in the holy palmers' kiss of lovers holding hands on the city streets, even faked in television adverts for holidays and toothpaste.

But he has never witnessed it quite like this.

Even a universe apart, a lifetime away from one another, the hold Rose Tyler still has over the Doctor's hearts is clear to see.

The look in those new eyes as they catch a few strands of blonde hair in the sunlight, when wartime music floats past his smaller ears as they cross another path through history, or (inexplicably, though he's sure the story would be a good one if he heard it) when they pass a statue of a Greek goddess Jack cannot name in a 33rd century museum – these are the signs of a man in love, as deep as the need he once saw in the eyes of an older, younger man who wore a leather jacket shield around his heart.

Before he'd met them, he would never have understood how their love grew with pain and separation, how they only needed each other more the longer they were apart where most people would have lost the intensity of their emotions and moved on. But now...

Now both of them are idealised, even idolised, by his time apart from them, his slightly falsified memories and attachment only enhanced by time and distance – Rose especially, unreachable Rose who did not abandon him, Rose who, too, was let down by their Doctor.

Now, he understands.

If he is honest with himself, he has loved them both for as long as he can remember.

--

They don't know he's watching.

If they did, they'd probably spring guiltily apart, blushing as though they think no-one realises what's going on. But it's been three long years for him (she won't say how many more for her) and that was one hell of a reunion kiss. It's almost charming that they honestly believe their relationship remains a secret when they've been so clearly crazy about one another since the beginning.

It's hours since everyone left the TARDIS to return to their respective lives – hours, even, since Jack and Donna declared themselves the only remaining passengers and retired to their (separate, much to Donna's dismay) beds.

He'd only got up to get a drink, fully expecting the rest of the ship to be in deserted darkness – but there they were in the kitchen, possibly the most unromantic location he can think of (second only to the bathroom), their tea-cups and chips forgotten on the table behind them.

He should take his cup and leave, he knows, find another kitchen and return to bed and pretend he's never been witness to such a tender moment between them. Instead, he stands transfixed, the strangest mix of emotions being played by the fingers of the hand that squeezes his heart.

The Doctor and Rose cling to one another in the middle of the room, two rocks with only each other for support in a sea of uncertainty and pain and loss, their desperate happiness stronger for all they have suffered apart. His kisses ghost across her face, his thumbs catching her tears. Next to her ear, his trembling lips whisper words the TARDIS will not translate.

I love you, she returns, again and again. I love you, I love you.

It's not going to be easy for either of them, Jack knows that – Rose has left behind the family she had always so desperately wanted, and the Doctor has to live with the constant knowledge that she is a human with a human lifespan and he is anything but. They're fighting, though, just like they always have done – for each other, for a love that is against all the odds, for a relationship that should have been impossible for so many reasons.

He never realised quite how alone he was before he met them.

Wait, Ianto had told him once, ever patient, ever silently long-suffering. But how can he admit, even to himself, that he is glad for his immortality? That he thanks this girl he loves every day for giving him the chance to wait until she is dead and gone to take his turn with the man they both so deeply adore?

He had Ianto – Estelle, John, the real Jack. He will have others. Perhaps, one day, when the grieving is over and the Doctor is able to walk past a blonde girl in the street without the constriction of his hearts visible on his face, he will even be able to call a small part of the Doctor his own.

But watching them standing there, even knowing that eventually the days they share will have to end, it is hard to believe that he will ever have a fraction of what they can call their love.