This is a sort of missing scene for "Utopia" so There Be Spoilers. Just trying to get inside the Doctor's head, I am. And posting this before it becomes irrelevant (i.e. before the next episode airs).

Double-drabble (200 words)

The sky was empty, with a hollow blind vacancy. "This isn't just night," the Doctor said. "All the stars have burnt up and faded away... into nothing."

"They must have an atmospheric shell," Jack surmised. "We should be frozen to death."

"Well, Martha and I, maybe," the Doctor replied, eyes still scanning the blackness. "I'm not so sure about you, Jack." The Doctor turned his head, staring at the Captain.

Their eyes locked. But seeing wasn't believing. The senses that screamed wrongness to the Doctor weren't his eyes. To his eyes, Jack looked the same as he ever had; dashing smile, handsome as a Hollywood superstar, even that anachronisic coat of his. Exactly the same. And that was the problem. Frozen as he was at the moment of his death, Jack would never change, never grow, never die. To the Doctor's time-senses, it was like looking at a zombie; an unnatural necromancy. Time was stagnant in Jack; there was no line of life, no branching of possibilities, just a tangled knot of nothing, looping back on itself. Even vampires were more alive to Time than Jack was.

No wonder the TARDIS had flinched.

But he himself, what would he do?