The Weariest River
Jack doesn't remember how old he is. Certainly older than he ever imagined he would become. Older even than the young alien Nurse Hame just teleported into the room.
Jack believes he was once awed by the Doctor's knowledge and wisdom, when he himself was young and human, but the feeling is lost in the haze of his memory, and all he feels now is love and protectiveness. And urgency, too, because he knows he hasn't long left to live, and he needs the Doctor to save all those people who are trapped below.
He watches as Nurse Hame explains the situation to the Doctor, and tries to remember whether the Doctor already knows who he is; time-travel can make personal relationships difficult, sometimes. He thinks it is the Doctor before he told him. Maybe it's even the Doctor before he found him again, that first time when they went to the end of the universe.
Which reminds him he has a message to tell the Doctor. But not now. Not yet. Soon.
First, they need to save the inhabitants of New New York. The Doctor is already on top of the situation, bouncing around and shouting orders. It feels a bit like old times, and Jack would smile if he had enough energy to do so.
The power goes down unexpectedly, and Jack is suddenly afraid that they won't succeed, that the people below will die. But the Doctor is already trying another solution. It won't work, though. Not without power, and Jack suddenly knows what he has to do, understands how he will be able to die, for good, finally.
He reaches inside himself and finds it, the golden particle of the Time Vortex that has sustained him all these years, from the moment when Rose and the Tardis decided that he should live. And lived he has.
He is tired, anyway. He has lived longer than any other being in the universe, saved quite a few planets quite a few times, seen and done things he'd never imagined in his wildest dreams, become a legend and an object of worship, and he rather thinks he's earned his rest.
Jack pulls and pushes at the golden particle, and forces it, all of it, into the main power, until the computers start again. The Doctor flashes his sonic screwdriver — and even after all this time, Jack cannot restrain a mental snort at the concept — and works his magic, and the motorway's ceiling opens up, and cars are pouring into the sky.
Jack remembers how everybody lived, the day he first met the Doctor, and surely it is fate that everybody should live again the day they part.
He can feel himself weakening, the Time Vortex no longer supporting him. His body — what's left of it — is failing, and his container is... cracking?
Cracking, definitely. A web of hairline cracks that spread and grow, the fluid escaping quickly, until the glass is falling down and him with it. The Doctor and Nurse Hame catch him and lay him gently on the floor.
He hears a voice, young and full of enthusiasm, outside. Martha, of course, beautiful Martha, who's a little afraid of him, and Jack can't help feeling saddened by the thought. Not that she'd know him anyway. Friendship only came later.
Jack takes a deep breath; he'd forgotten what air tasted like, all these years as a head in a jar. The Doctor is urging him to live — he has no idea, the foolish youngster — and Nurse Hame is speaking of the legends that people wove around him centuries ago. Legends he started, actually, mostly as a way to remind himself not to forget to give his message to the Doctor when he finally dies.
And now's the moment, so he says it. In Earth-time 21st-century English, just to make sure nothing's lost in the translation. "You are not alone." Jack forces himself not to remember what the short sentence implies. It will all be cancelled in the end anyway, and it will also mark the beginning of the Doctor's healing, something he's desperately needed ever since the first time Jack met him.
And now everything he needed to do is done.
So he lets go.
END