He wanders solo along the shoreline as purple creeps into the evening sky. She lets him go, finding driftwood to build a fire, stripping off her salt-stiff outer layers to wash with tomorrow's rainwater. The sun is a finger's width above the horizon when he returns, the sky filled with stars beyond count.

"I don't recognise one of them," she says. "Not a constellation."

"You're a long way from home." He sits beside her. "I can teach you. That one there… that's the school teacher. See, those three stars line up so she's wagging her finger at you."

"Hmm, I do see." She sights along his arm, and nudges his pointing finger right. "That means… that one there must be the stick insect, avoiding her questions."

He gives her a withering look. "You haven't changed."

She wrinkles her nose. "I have. You just bring out the worst in me."

"Yes. I suppose that was always the problem."

There is such an aching sadness in his face her hand moves without volition to cup his cheek. "Doctor," she says, for want of anything better. "That's not what I meant."

"There was a story," he says at last, "on one of the Ri'Jinn homeworlds. About the Circle Time and who built the first stone portals. I went to investigate because…" He looks confused for a moment, unable to recall his precise reason for violating jealously guarded territory.

"Because you're you?" Clara supplies, knitting her fingers with his.

"I suppose. I was captured. Tortured. They thought I knew how to translate some ancient carvings, that I could give them access to Time That Was. I couldn't. Even the TARDIS can't translate the language they're written in. But I had seen it before; a long time ago on a planet called Krop Tor. It was a prison for an entity of great power and monstrous evil. We destroyed it. Rose… Rose destroyed it."

"You didn't tell them?"

He makes a noise somewhere between a laugh and a sob. "I told them everything. Krop Tor fell into a black hole centuries ago and the Beast fell with it. It didn't matter. But there was something else, their commander said. Secrets I was holding, supressed memories that avoided their most sophisticated extraction techniques."

Oh no. "The neuro block."

"Yes. It took a very, very long time to break."

Stars wheel overhead in the silence. His knuckles are white, so tight is she holding on to his hand. "Doctor, I'm sorry."

He shakes his head, eyes dark. "Not your fault. Anyway, it broke and they gave me one last chance to translate the carvings. I knew I wasn't going to be able to, my head was just full of…ah…" The words seem to stick in his mouth.

"Full of what?" she asks, confused.

Silence balloons, his throat working awkwardly. "You," he manages eventually.

She closes her eyes, fighting against tears that threaten to fall; failing. "How did you escape?"

"I read the words."

"But-you just said... How?"

"Maybe a better way of putting it would be that the words read me. There were two tablets. Two consciousness trapped in stone. One a creative force, a Disciple of the Light. One a destructive. The first… chose me. The second went to the Ri'Jinn commander."

"But it's not controlling you now?"

"Light doesn't work like the darkness. It doesn't take control. Wouldn't be very Good if it did, I suppose. It's more… like a hybrid."

"No," she says softly, "no, the Hybrid was-"

"That's the trouble with ancient prophecies," he shrugs, "they tend not to be terribly specific."

"So what happened next?"

"What do you think? Me being me... I ran."