Disclaimer: I (sadly) do not own Doctor Who.
"There is always a light."
The Light.
There it stands, burned at the centre of the universe. Hidden away from the fabric of time itself. It was there long before anything, it brought the dust and rock and particles together, and it collided them, running throughout all of time and space, fuelling the universe. Fuelling life, saving.
It's a thought, a seed spun, hardwired into every strand of DNA. It's immortal, impenetrable, impossible, and so very human. It's always there, even when nothing else in. When every fibre is burning, falling, collapsing, it saves someone. It keeps someone. It lives on.
It's the only thing that can't be killed or maimed, not by him or anyone. It's not to be confused with faith, either. Faith can easily burn, the wrong thought at the wrong time and faith will die. But this seed, this fuel, can never be quelled.
His feet, that have graced a thousand planets, step cautiously into their dystopian world. He can see the pain, the suffering, radiating from their souls. But that thing, that thought, that emotion, it's here, hiding under the surface, beating their hearts. Keeping them alive, reassuring. He can see it in their eyes.
It's the start of every 'maybe' and every 'if'. It's wonderful, wicked but oh, so very kind. It's the light, in the dark abyss of time and space.
It is there in Rose, Donna, Martha. It is there in Amy, Rory, River. It is there in the Doctor.
It's hope.