("How long are you doing to stay with me?" "Forever.")

He once told her it's unwise to place a bet with a time traveller. After all, he can glimpse at all the different timelines and see all possible outcomes of events, and he's never been shy about cheating like this.

She once told him something her mum told her when she was young, something she truly believes in- nothing is set in stone. We make our own destiny with the combination of choices we make throughout our lives. Nothing is pre-destined- our futures are a result of our decisions summed up.

He hates it when they are both right.

At a timeline that he sees...

"Five."

He hurriedly fumbles with the Rubik cube in his hand. His thoughts are scattered all over the place- how beautiful Rose looks in a simple jeans and shirt, the speed of sound through uranium, the orange skies of Vertenium, and how he can see tiny specks of dust floating in the air, illuminated by a beam of light creeping in through a crack on the TARDIS door. If he thinks about it all in a grand scale, they are exactly the same- tiny dots of life floating through time and space, destined to be beautiful and tragic in the end.

"Four", she counts, her eyes fixed on the countdown app on her phone, her mind wrapped around the things she can do when she wins the bet. Hello, New New Hawaii.

He thinks of Susan, K9, the Daleks, and everyone and everything in his timeline that has led him to where he is now. He has two regenerations left, and the woman reigning both his hearts has a finite lifespan. Suddenly eternity seems too long and too short at the same time.

"Three", she says triumphantly.

"There!" He places the cube on the console table, his melancholy musings carefully hidden behind the grin of smug satisfaction on his face that she so wants to wipe off with a snog. "Did it in under a minute. Brilliant, me."

She snatches the cube up, trying so hard to find even one misplaced square in any face, or even the slightest indication that he used some trick. "I can't believe it", she says when she finds none.

He shrugs, leaning against the console with not a hint of modesty in his features. "Told you I can do it, didn't I?"

She rolls her eyes. "You told me you can sing too."

"I can sing." He protests, rubbing the back of his neck. "I am just not good at it." He mumbles so quietly that she can barely hear him.

She shapes her mouth into the cutest pout she can master. "So you really won't take me to New New Hawaii?"

"New New New Hawaii", he corrects, "And no. Those were the terms of the bet, Rose. Off to fourteenth century Kriptilina. Allonsy!"

And then...

"Five", he counts, the clock ticking at the back of his mind, a never ending white noise that comes to him as naturally as the beat of his hearts or the expansion and contraction of his lungs with every breathe.

She gulps the liquid from another glass, aims a ball at her target, and misses it by a foot and a few inches. Years of experience of playing beer pong is supposed to make her a pro, but apparently not when it comes to alien alcohol.

"Four", he says, the panic inside him rising as he scans the pub for the most feasible exit route.

She swears the room is spinning, or maybe the planet, or maybe it's just her. She misses another shot and mentally scolds herself for challenging an annoying alien prince to a game of beer pong as a means of settling the bill. Clearly not her best move, she's growing reckless day by day.

"Three." He knows it's a lost cause and wonders if she can leg it in her inebriated state. "Two", and "One."

He grabs her hand and they run in a way that would put a certain cartoon coyote to shame. When they reach the TARDIS, she hurls on his favorite pair of converse, and he bans her from getting drunk during battles that their lives depend on.

They laugh as they pant, and behind that cheerful sound is the hollow tick-tock of the clock at the back of his mind. He can feel it counting down the time he has left with her to treasure amazing moments like this. Tick, tock, tick. Atoms dissipating, heart beats fading- human life is so fragile at its best. He wonders where humans go after death. Do they have a ghost matrix like they had in Gallifrey? Or do they just fade away, disappear into the Void like they never even existed?

And then...

They bump into Keisha one day and she's in need of help. It's too much of a coincidence to be a coincidence, but he has never been able to resist the siren call of a mystery, and she can never turn her back on her best friend.

So they set off on what would be their very last adventure in London. There's a chronoclock on Keisha's neck, a street hidden in plain view, and a woman called Me that he guesses he meets sometime in the future. What feels like the last hour he was alive is a blur, because the woman who looked into the heart of the TARDIS has once again put herself at stake by passing on her friend's death to herself, and this time he cannot kiss it better. His face darkens like storm clouds, and he threatens to destroy the entire street, the entire planet, the entire bleeding universe, he bargains, offers up his remaining lives, his everything, but in the end, there is not a thing he can do. He is going to lose her. Again.

He liked it better when he had to burn up a sun to say goodbye.

"No revenge, do you hear me?" She barks, her facade of bravery cracking at the edges.

"No wondering off, but you still did what you did", he accuses bitterly.

She shakes her head, pleading with him. "No, no, no. Don't go back to the man you were when I first met you."

"Was he that bad?"

"He was fantastic." She says with a sad smile, "But he was hurting. And I can't let you hurt, I can't."

"Then don't go." He begs, holding her hands tightly, hoping there is some power in the universe that will grant him this one miracle.

"I don't want to go", she tells him, squeezing the fingers interlaced with hers. "But I have to. And I want you to have a fantastic life. For me."

He takes a deep breathe to steady himself. "If this is our last moment together, then I won't lie to you. My life is over without you."

"Don't say that!" She scolds, tears streaming down her face now. "Donna told me about your little suicidal stint. Don't you dare do that again, you daft alien! My mum and dad and little brother are on the other side. You have to look after them. You have to look after the Universe. Promise me you will?"

He shakes his head vehemently, a single tear rolling down his cheek. "I love you."

"Quite right too", she mimics, with her tongue against her teeth in a failed attempt at playfulness. "And if this is my last chance to say it too, then, I guess,", she takes a step back, away from him, and looks him straight in the eye, pouring all her love and longing into her hazel irises, "My Doctor, I-"

Her lips part and her hands raise up like the wings of a swan that is ready to fly for the last time. There's a scream that he vaguely registers and black smoke and a raven flying away and the lifeless body of a blonde woman next to his feet that is definitely not Rose Tyler's. Because it can't be. No. It can't.

He's teleported away then, not even given a chance to give the woman he loves a proper burial, and he wants to die so badly. But he keeps coming back to life again and again and again for millions and millions of years, and he loses a little more of him every time he sees her smiling face flash before his eyes and then fade away.

Happy endings are really a myth, because in the end, billions of years and deaths and torture later, he doesn't remember much about the woman he loves, or the promises he made, and is just a dark, bitter, angry, ruthless Time Lord that the world starts calling The Valeyard.

At that wretched Bad Wolf Bay...

He knows the outcome, the fixed point in time, the one haunting inevitability- he is going to lose her. In every timeline, in every life they build together. It's a curse sometimes, knowing the future.

And at other times, it's a gift. It leaves him with the option of choosing the best possible future for her- one where she is happy and safe and with another him.

It's a bittersweet tie with the universe, but he will take it.

"Does it really need saying?"

("Her name was Rose.")

A/N: I have a thing for sad plot-bunnies, I know. Hope you liked it though. :)