There are pieces of Sherlock's mind missing, fragments of memories that he can't quite put together; it's nearly enough to drive him mad.

"A falling star feell from your heart and landed in my eyes."

Sherlock's hands skimmed the wood, fingers trembling as he searched for some other explanation, but nowhere in his endless knowledge was there anything that could explain this. He circled the police box once, twice, and then stumbled back through the door, staring at the strange man who just stood there and waited, a smile tugging at the corner of his mouth.
"It's bigger on the inside," Sherlock breathed, turning in a slow circle and shaking his head in disbelief. He looked back at the man; the grin broke fully across his face and his eyes lit up, like stars bursting into being.
"I love it when they say that," he responded, and something in the tenor of his words made Sherlock's heart pound, his chest aching with the weight of all the things he didn't understand.

"I screamed aloud as it tore through them, and now it's left me blind."

All he knows is that somewhere, in this great gaping hole in his memory, veils were ripped from his eyes. The universe was laid before him in brilliant clarity. And now it's gone. Maybe the light of all those galazies was too blinding, because now sees nothing at all.

"The stars, the moon, they have all been blown out; you've left me in the dark."

There was someone else; he knows that too, knows it only because their absense aches now, wrenches at his heart with such a force that not even John can make it stop. Whoever it was, he misses them more deeply than he's ever missed anyone in his life, and yet hates them with that same passion - because they've left him here, to suffer through the unknown.

"No dawn, no day, I'm always in this twilight in the shadow of your heart."

"What am I without you? Tell me that, because I don't know. I was everything before, Doctor; if only you could have seen the world I ruled! To all those fools at Scotland Yard, I was God. But I can't be that now, not with you. I'm you're shadow. And without you, I'm just nothing."

"And in the dark I can hear your heartbeat; I tried to find the sound."

At the end of every new horror they see, every planet they manage to save, they stand in this same place: the Doctor leaning against the wall with the weight of twelve centuries on shoulders that look far too young for it, Sherlock leaning over,eyes closed, both hands pressed against the Doctor's chest, feeling two hearts beat against his palms.

"But then it stopped, and I was in the darkness, so darkness I became."

Sherlock lies awake at night, staring into the darkness, begging it for an answer, but it's so deep and black that it cannot answer. His surroundings mirror the state of his soul; he has become a black hole, a void that will never be filled no matter how much he tries.

"The stars, the moon, they have all been blown out; you've left me in the dark."

They'd shot through supernovas and exploding stars; he'd watched galaxies being created and destroyed. "It's so much," Sherlock said. "So bloody much. Every second, it all blows up in my head, over, and over...Christ, is it like this for you all the time? How do you stand it?"

"No dawn, no day, I'm always in this twilight in the shadow of your heart."

John has started to notice how detached he is form reality, and he's worried, loyal soul. But Sherlock can't find it in him to dash off on a case the way he used to, not when he knows that everything he does is barely an echo of something and someone far greater than he could ever be.

"I took the stars from my eyes and then I made a map; I knew that somehow, I could find my way back."

"You'll forget this," the Doctor told him, somber but matter-of-fact. "All of it."
Sherlock stared at him. "I don't forget things. Not if they're important." And he commited it all to memory, the doctor, the TARDIS, the places they'd been and the things they'd done, stored it at the center of his mind palace and walked the path to the memories a thousand times so he knew it well.

"Then I heard your heart beating; you were in the darkness too; so I stayed in the darkness with you."

They were floating somewhere nameless, surrounded by the cold empty vacuum of the universe. The Doctor mentioned that they had to go back, eventually. Sherlock just shook his head. He'd like to stay there awhile yet. He doesn't mind the dark, as long as he's not alone in it.

"The stars, the moon, they have all been blown out; you've let me in the dark."

"You can't do this," Sherlock burst out, as if he had suddenly been granted veto power when they both knew who was really in charge. "You can't. Not when I've seen so much. Universes, worlds, it's all so bright - and now you're going to leave me in a place where none of that exists, where I've never seen anything and just stumble blindly through the world? Tell me how that's fair."

"No dawn, no day, I'm always in this twilight, in the shadow of your heart."

"You won't remember it. Nothing will be different," the Doctor told him again.
"But it will. I'll remember it, but I'll never get it back, and how am I supposed to go on living with that? I'll have all these memories of this, of you, and my life will be nothing more than a shadow of it all."

"The stars, the moon, they have all been blown out; you've left me in the dark."

The doctor gazed out at the galaxies that lay before him and sighs. Sherlock didn't understand. After twelve hundred years, there's nothing magical about this anymore. It's the look in his companions' eyes when he shows them the universe for the first time that makes it new and exciting again. Without someone by his side, he's just sitting in the dark, staring at the same old stars.

"No dawn, no day, I'm always in this twilight in the shadow of your heart."

"You left me more alone than I ever left you!" The Doctor yells, screaming to the empty air as if his voice will carry across the miles and the years. "You get to go home. You get to forget. I have no home, I will always remember, and I will always be living with the pain of losing you."