She'd have to time everything just perfectly. It takes a lot of power to create a projection from a closed-off planet, but coordinating with the TARDIS to connect at the proper point in his timeline is nearly impossible. Nearly—she always did love that word.

"Are you sure you're ready?" Cal asks.

She can already sense the timelines rewriting, reeling him in like a fish on the line. No, she's not. She wants more time to check the calculations, to harden herself against his grief. But it will have to do. "Don't stop until I tell you." They'd never tried this before—she hadn't thought it worth the risk. But the winds whispered of Trenzalore, and she isn't done protecting him just because she'd died.

Cal sends the transmission.

It doesn't hurt. For a moment, surprise, though pleasant, blocks all other thoughts. It's been so long since anything surprised her in Cal's automated world. Blue light shines on her skin. On, not through—she's solid, or appears to be. A gift from the TARDIS, River knows, and wonders if she'd be real enough for one more kiss.

But he isn't there—a girl is, dark-haired and small. Clara. River had read all the records, extrapolated from the holes in history, hoping he'd kept his promise to find someone. And of all the people in all the universe, he fell into the same trap again. An agent of the Silence. Unaware, yes, but she knew too much about programming to assume that made things any simpler.

She wants to tell the girl everything—that how you came to be isn't as important as what you chose to be, that weapons can be re-forged and memories can shape the universe, but there isn't enough time for that. "Whatever you're doing, don't."

"He needs you, not me." Clara doesn't startle or jump at another voice—her gaze is fixed on the time rotor. "Without me, he'll never reach Trenzalore."

"Please—let me explain—there are fixed points—"

Clara's body begins to glow. "Not yet. I can reach him, warn him."

Before River could do anything, the light from the column wraps around Clara and she disappears. The girl is only echoes now, the same face repeated a hundred times throughout history.