What with all the wibbly-ness going around I figured that you know, this isn't impossible. Enjoy.
"No! No! No! No!"
The Doctor tore along the shore of Silencio Lake; kicking up sand in his wake. The burning boat was the only light for miles. Its flames were reflected in the water, licking away at the ripples surrounding it.
Time was running out.
He struggled out of his jacket, threw it over his head. 911 years old and not one swimming lesson – He was going to regret this. The sky was dark, speckled with bright stars, 'Not bright enough' His last thought as he dove into the icy lake. The ability to see underwater was not something that the Time Lords had ever developed. He was freezing, and heavy. So heavy – 'Damn clothes'. He couldn't stop now, she was so close, so frightened. She kept him alive. And yet look how she'd killed him. Mixed messages most definitely. The Doctor could barely make out the lights of the helmet getting closer. There it was. The spacesuit.
Fingers stretched out before him, he grasped blindly at the dull lights. Before he knew it he could feel the shape of the helmet. His fingertips tapped on the glass visor. She was still trapped inside.
"River!" he cried spouting a mouthful of bubbles into the icy waters. The Doctor worked the button of his sonic desperately, unsure if it would work at this depth. Green light flashed in an unstoppable flood. It lit up the whole lake.
From the window of a nearby gas station the green flash was clocked by the watchful eye of a younger Time Lord. He grinned to himself as he set down the Tardis blue envelope on the table beside a bottle of cola. Better to not start his drink until he'd gotten his special straw.
The lights in the suit went off, the Doctor; still clutching the suit was plunged into total darkness. River's life support system was disabled. He had to get her to the surface and out of that god awful contraption. He didn't know how much breath he had left, already he was becoming dizzy as he forced River up over his head towards the surface.
When his head finally broke the water's surface he gasped and spluttered as he staggered out of the lake dragging the helpless River Song behind him. They flopped onto the dry sand. The Doctor turned her onto her back, his hands pressed against the glass visor.
"I'm getting you out of there," he told her frightened face. The Doctor worked his screwdriver along the seam where helmet met suit, "Sssh," he soothed keeping on hand firmly on the visor to calm her. There was a sharp click as the locking mechanism severed. The Doctor slid the helmet off over River's mass of curls. He tore at the suit, ripped it apart in great fistfuls.
River Song lay trembling in her graduation gown surrounded by suit debris. The Doctor sat back on his knees, breathless, fists still clutching spacesuit material and damaged bits of wire. He dropped everything and pushed his wet hair out of his eyes.
"River?"
She reached out a trembling hand towards him. He pulled up out of the suit remains. Her arms locked around him tightly, her whole body shook in his arms. She didn't care how wet he was, she needed to hold onto him. The man she loved. The man she'd killed.
"River…"
"I… I killed you…" She sobbed into his shirt.
"Sshh," he whispered into her hair; his eyes glanced to the fading embers of the half sunken boat in Silencio Lake; his heart sank slightly, "We all have to die," he told her. River's grip on him tightened.
"Iloveyou" Her voice was muffled against his shirt. She brought her face up to his, "I love you, Doctor" she told him. For the first time in their complicated relationship the Doctor took her face gently in his hands and led her lips to his. He was drenched and she was frightened; both sought comfort in the others tingling kiss, "But I still killed you"
The Doctor smiled as the tears welled up in her eyes, "River, you kill me a little more each time you walk away. There's only ever been you who could kill me" He brought their lips together once more, "My wife, My River, My lover, My killer" He grinned, "Who else but you?"