The Cloister Bell tolled.
Sparks spewed from the cracks in the white-round walls and rained blue and gold into the fires that consumed the console; the thunder of a collapsing star roared in the beams; the pillar shuddered and groaned and cracked and flashed with the light of the universe; the floor collapsed like a playing card, and the first thing the Doctor knew when he opened his eyes was the sharp of a broken lever in his clinging fingers and the swing of his feet in he air. For a silent moment he was weightless. Then the fiery console crashed into him; he crawled burned and bleeding and regenerating across the uneven floor, kicked the door and fell backward out of it, coughing, into the open sunlight and into the blood-sight of a reaper.
His eyes flew open, he threw himself to the side; the reaper's claws crushed the warm tarmac where he had been. The beast chirred, flashed its fangs, flapped its great leather wings, and leaped into the sky with a powerful wind.
He coughed and yanked at the scarf that was choking him. It fluttered to the tarmac while he scrambled to his feet and threw himself against the edge of the rooftop; the reaper disappeared into a tear in the sky. He craned his neck, breathed through his teeth, squinted through the clouded sunlight at the spot where the last of the monster's tail had vanished. He leaned forward and looked down over the Thames. His hearts stopped.
Beyond the open TARDIS door behind him, the Cloister Bell tolled.
He modeled his reflection in a boutique window at the London waterfront, rubbed his round head, flapped his ears, tried out a few rubbery expressions, straightened the lapels of the not-Doctor's old leather jacket, bruised and darkened and smelling faintly of the ash of a burning Gallifrey. It was only right that he kept one thing, one remnant of a people he owed so much, so he could with mild conscience shove the rest of the past hundred years' war into a locked room in the back of his mind. There were other things, right now, that demanded his attention. Things that didn't make sense. Things that twisted and snapped the limits of reality. Things like reapers, black smoke, collapsing universes, and a peculiar lack of ferris wheels at the south bank of London.
Nothing was wrong, yet everything was wrong. The streets were full of polished businessmen, phone-wielding tourists, teenagers with bright shopping bags. They were drinking coffee at cafe tables, taking selfies in front of old statues, walking and talking and never looking where they're going. But the London Eye had been dismantled, and houses were burning at the edge of the city, and like true Londoners they carried on blindly. Anger rumbled in his chest, and it surprised him.
His regeneration and the aftermath of what he'd done must have thrown the TARDIS into a pocket universe, where Something had happened that was never supposed to have happened. And he was stuck here, in this false timeline, until either he made this wrong happening un-happen or this universe collapsed on top of him and all the hapless humans in the city. He paused at a bin on the street, leaned over it with curious eyes, and he plucked out the day's Times. August 5, 2014.
A howling siren echoed throughout the waterfront, and -- while the Doctor stood blinking with an open newspaper before him -- everyone scattered. The businessmen ducked into coffee bars; the teenagers squeezed into alleys; police directed frightened tourists to the nearest safe zone, waving lights and cones. A rasping, hideous screech rose in disharmony with the siren, and the Doctor turned in time to see a reaper diving across the rooftops, its wings a shadow over the fleeing humans. As he watched, a black Torchwood van screeched around the corner; attached to its roof was a weapon he recognized as Dalek technology, bright and silver, aimed high at the screeching beast. The laser whizzed as it powered up, and the Doctor flinched when it fired with a force that shifted the van on its axles; in a burst of blue light the reaper disintegrated, leaving no trace at all that it had ever existed.
Hours later, the Doctor strode purposefully into a quaint little restaurant on the outskirts of the city, the folded newspaper in his hand and a friendly grin on his face. He'd been following the pattern of reaper sightings when he'd noticed, with a curious quirk of a brow, that without making so much as two left turns he'd passed this same local eatery twice. Never one to believe in coincidences, he dropped into a booth and cracked the newspaper open again. Surely there would be something here to nudge him in the right direction.
That obituary of Harriet Jones on page 10, for instance.