He rounds the corner and stops, stunned. She left him—she left the letter—she can't be here. It must be her past self, a time ghost or an echo; these things happen when wires get crossed inside a rackety old TARDIS.
"Doctor," she says, voice choked. She sounds as bewildered as he is, but perhaps he's just projecting. She shouldn't be surprised, not if this is a version of her that's still travelling with him.
But if she's still with him—
He takes her suddenly in his arms, whispering nonsense; feels her head under his chin.
Then she's gone.
She turns at the sound, then freezes. It can't be him. He's dead—will be—will have been—anyway, it can't be him, not her Doctor.
Temporal something-or-other, she guesses he'd say if she asked. But she's seen enough of the universe to believe in ghosts.
She thinks she says something. She doesn't think it's a question.
But he's so present. She can hear his rustling velvet, feel his warmth, faintly smell that peculiar sweetness—and oh, she's in his arms. "Charley, my dear," he's repeating, "come back, don't go."
She's trying to answer, trying to promise, when he vanishes.