Disclaimer: Doctor Who belongs to the Beeb, Star Trek belongs to Gene Roddenberry, all I have is my Microsoft Word.


String theory.

The universe peeling away, moment by moment, into an infinite amount of possibilities; it has no limits, no restrictions, it curves and swells, with the beauty of a Fibonacci rose.

The Doctor had once told his Rose that the other dimensions, other timelines, were closed to him.

It was mostly true.

Mostly.

~~~*~~*~~*~~~

The orange glare of the sky, and the crenulated cityscape, reminded the Doctor vaguely of his homeworld, as he peered through the arches of the walkway. The polished floors gleamed a silver grey, and the linear architecture looked deceptively simple; spinning up, and dropping away at sharp angles.

Vulcan was an old world, populated by an old race, and it was still in existence, which meant, for once, he was running ahead of schedule. It made his job simultaneously easier to carry out and difficult to handle. For one thing, the person he had come to reason with was a lot shorter than he'd counted on.

He came to a halt.

Mouth bloodied, back stiff, the boy sat with a controlled stillness on the stone bench in the archway. He stared sightlessly at the horizon.

"Spock?" he asked quietly, looking down at the boy.

Spock's eyes slid up and sideways, and studied him intensely as he stood. His movements were measured and precise, the very epitome of a well brought up Vulcan child. "Yes, may I help you?" he asked coolly, and the Doctor noted the almost imperceptible jutting out of the chin. He smirked.

"I'm the Doctor," he said. "And I'm here to talk to you about your temper…"

And there it was, irrefutably; the boy was glaring at him.

The Doctor smiled widely. "Yeaaah," he drawled. "That's the temper I'm talking about."

~~~*~~*~~*~~~

Steering the TARDIS onto the engineering levels of the Enterprise, mere hours before a temporal event, was almost suicidally difficult, but the old girl didn't let him down. He poked his head out and winced as the various emergency alarms clamoured for attention. That wasn't his problem to solve.

His problem was a lot more difficult.

He found Spock's quarters with ease. After all, it was marked out on every holographic Enterprise tour in the Federation History Museum. At least, it would be. He pressed the door's com, and got no answer. It didn't surprise him. He pulled out his sonic screwdriver and hit the appropriate settings. The door slid open.

He was sitting on the edge of his bed, hands on lap, the body rigid with grief. "You didn't tell me everything," he said, through gritted teeth.

"I know, I'm sorry," the Doctor said.

"Why are you here? I did as you asked. I gave him the bridge," Spock said.

"Yes," the Doctor said. "But there is one more thing I need you to do."

"And what is that?"

"I need you to help him."

Spock threw him an incredulous look. "There is no logic to your request," he said.

"No, perhaps not," the Doctor agreed. "But there is hindsight."

Spock's nostril's flared as he stood. "I see," was all he said, before he left.

The Doctor sighed, he wished there could be an easier way.

~~~*~~*~~*~~~

The space port was a multitude of species and the Doctor let it all wash over him, a soothing din, as he sat and sipped his tea.

After a few minutes, he was joined at the table. "It is good to see you, old friend."

The Doctor gave him a half smile. "I hear you're shipping out to the new Vulcan homeworld."

"It seemed the right thing to do," Spock said. Lines creased around his face as his eyes smiled ruefully.

"You could come with me instead?" the Doctor suggested tentatively.

"No, thank you, I remember how well that turned out the last time," Spock said dryly. "It's best we leave it at that."

The Doctor pulled a face. "So, that's it, then. We did it; we averted the dark and terrible future and all is right with the world again.

"So it would seem."

"You never did tell me how you convinced Kirk to go along with it."

"I told him he had a destiny," Spock said, with the smallest quirk of the eyebrow.

The Doctor burst out laughing. "And you let his ego do the rest," he said. "Brilliant!" He sobered. "You hate me, you know. The you in this timeline, that is."

"Probably," Spock said. "I would in his place, but we both know that preventing the destruction of Vulcan would have only lead to worse destruction - after all, that was the timeline we created the first time we tampered with it."

"And the second," the Doctor said quietly. "Sorry."

Spock stood, and rested his hand on his shoulder. "You did the best you could," he said. "Thank you."

The Doctor watched him walk away before sliding his psychic paper along the credit bar embedded in the table. He had things to do, a timeline to slip across, a different future to explore.

But first he needed to catch that tribble that had somehow managed to squirrel its way into the TARDIS's library.

~~~FINIS~~~