She was silent. He never remembered the Doctor's TARDIS being quiet, before. She was always humming, always alive, just beyond the reach of his understanding but so very alive.
Nothing hummed, nothing glowed, nothing moved. She was silent. She was dead.
Maybe he was missing something, some ancient Time Lord secret he had no hope of guessing. Maybe no TARDIS grown away from the orange skies of Gallifrey could ever truly live.
Or maybe... Maybe she only needed a jolt, a point in the right direction, a spark. A little life, and he had that in spades.
He went away, and came back with a knife. He opened his veins, and watched as the blood fell to her dark, rough-carved floor. Vortex energy sparked and gleamed as it hit the floor, or maybe just behind his eyes as he died.
He can feel her. She's humming, in his head and in his blood, impossible to ignore, and now it sounds like a heartbeat, and now like distant singing, and then she's throbbing once more in time with the beat of his heart.
He wonders if this was what it was like with the Doctor, understands now the affection with which he'd look at that little blue box, run his hands over the controls, talk to her like an old, old friend...
She's so young. Young and full of life and energy and she reminds Jack now what it was like to feel that way. She's timeless, understands the years Jack has watched pass by and will weather all of the rest of history with him. And she wants to fly, to be anywhere but here and now for the simple reason that she can.
Jack strokes the controls - rudimentary, nothing as wonderfully advanced as the Doctor's TARDIS, but all his - for just a moment, and then keys in a series of commands. She takes off, Jack gripping the controls so as not to fall over, and he laughs as the two of them hurtle through the Vortex together, into anywhere.