Ever since Donna had spoke those words, those two terrible, glorious words, he had locked it up, bottled it away, hidden it even from himself.
The TARDIS' warning chimes, the slow, sonorous gongs that told him of the end of all things, seemed to match his heart. Dread at the looming tempests, but Bad Wolf is returning. It fused energy and purpose and potential into him, and he buried it away, almost frightened by this desperate need for her. So he buried it into the depths of himself, because if he thought of her, he would be consumed.
"Think Donna, when you met Rose in that parallel world, what did she say?" He knew that Donna's memories of her alternate life were fragmented at best.
"Just… the darkness is coming."
"Anything else?" he insisted, and hushed away the exultant whispers that sang, She's coming back to you…
"Why don't you ask her yourself?" Donna's eyes, so kind.
The barest of nods, a slight shift in Donna's line of vision from his face to over his shoulder, and he understood.
The world stood very still as he turned and saw her.
Small, remote, but close, so real, so attainable. It broke free, crashed over him, and he needed her. Needed her hand fitting between his fingers, her grin showing off to his, her eyes sparkling for him.
And suddenly, he was running.