At the sound of the TARDIS, Jack was full of hope. After more than a century, his long wait was finally over, he could get back out among the stars with Rose and his Doctor, shake the dust of earth from his feet, be free again. No more responsibility of leadership, sending good people into danger, he’d be a follower once more, a role he felt far more suited for.
But the TARDIS tried to run from him, Rose was gone, and the Doctor, in a new and unrecognisable incarnation, rejected him for being ‘wrong’.
He no longer belonged there.