Disclaimer: How I wish I owned them! Anyway, I don't; they're the property of the BBC.
He awakens, sweating, a ringing in his ears and the knowledge of loss surrounding him. Such dreadful loss. It's the same dream, again – the same dream he's had for as long as he can remember, though he knows somehow he's been having it for a long time. This is what happens when you destroy a planet, when you are the last of those you have loved.
Sitting up, he reaches for the water beside his makeshift bed and gulps down half the glass. His heartbeat is steadying now and the dream is receding. The high windows show a shaft of dawn light – no point sleeping again, even if he could. He swings his legs out of bed and stands, preparing for another day defending London against its attackers.
The dreams do not go away, even after he has company at night. He falls asleep listening to Rosita's steady breathing in the next stall and wakes to find her cool hand on his brow.
"Shhh, Doctor," she says, "it's all right, I've got you. Won't you tell me what you're dreaming about?"
But he can't – not precisely. When he wakes the dream fades into a confused blur of fire and noise and metal, and he cannot remember what happened apart from that he lost everything that mattered to him.
Later, after the Cybermen have been vanquished and a long and cheerful Christmas dinner has been consumed, Jackson Lake asks the Doctor – the real Doctor, the one and only, the last of the Time Lords – about the dreams.
"You have them too?" he asks, meeting those ancient dark eyes. "The dreams?"
"How do you stand them?" Jackson pursues, needing to know.
The Doctor shrugs, and looks away. "I don't sleep much. Can't dream if you don't sleep."
"What are they about?" he says.
"You know that," the Doctor returns. "It was all in the infostamp – what I am, where I'm from, what I've done. You know it now, but you'll forget."
Jackson nods. "But you can't."
"I push it away," says the Doctor, still not looking at him. "Tuck it to the back of my mind, pretend it never happened and that I can still go on and everything's all right. But there's an empty space in here," he taps his forehead, "where they should all be, and though I hated the whole lot of 'em – pompous, self-righteous idiots – they were part of me. And they're gone, and it's my fault, and so I try to forget and I know I must not." He turns his gaze on Jackson. "D'you know, when I met you and I thought you were me, the next me, I thought how good it would be to forget. I was glad I might be you soon, forgetting."
Putting out a hand, Jackson rests it on the Doctor's shoulder. "I might forget the dreams, but we won't forget you, Doctor."
The Doctor smiles then, a small, grateful half-smile.
"Thank you," he says. He steps forward, adds, "this won't hurt. Call it a Christmas present," and places his fingers on Jackson's temples. There's a sudden, swift, unfamiliar pressure and then it's gone. The Doctor turns and disappears into the snow, towards the TARDIS.
That night Jackson Lake dreams again, but this time his dreams are not of flame and loss. This dream is of glory and joy and wonder. He dreams of a planet glowing orange in the sunshine, the tips of the distant mountains shining red behind the great city. He dreams of worlds where the grass smells of apples and planets where the very surface is a great glimmering mass of sapphires. He dreams of the fantastic, brilliant, madness of the TARDIS and of many hands, many beloved people steering her to freedom.
In the morning he wakes exhilarated and refreshed. A Christmas present indeed, one to be glad of. Now, he thinks as he dresses with a lightness of heart he has not felt for weeks, he understands the Doctor – the pain and the joy. And though his grief and loss are still great, Jackson understands that his joy, in his son, will carry him through too.