River blinked back tears at the carnage around them. She had to pull herself together; the Doctor was probably hurting worse than her. She turned to him, catching the look of deep sorrow and self hatred. "You can't save everyone, Doctor," she told him softly.
The Doctor briefly bowed his head. "I wish...I wish sometimes we could. That everyone lives."
"Sweetie, that would never happen to us," River couldn't help but say bitterly. Someone always died. No matter how hard she tried, lives were always lost.
The Doctor gave her a concerned look. "It can happen, you know."
River snorted and spun around, making her way to the TARDIS. The Doctor sighed and with one last mournful look followed her.
Once the TARDIS doors were closed, the Doctor approached the console.
"I need to show you something. This is going to be very dangerous and very illegal. I'd have my TARDIS taken away for a decade and be banned from all time travel if Gallifrey was still around. This will be breaking a dozen time travel rules, but...you need to see this." The Doctor took a deep breath, mentally preparing himself for that day.
"Doctor, what are you doing?" River demanded.
"Something stupid and reckless." The Doctor quickly put in the coordinates, making sure to have the right time. "I'll have to cloak her and land noiselessly with as little disturbance as possible. We won't be able to be very far away from the TARDIS, but you'll be able to see, and more importantly, hear."
"Doctor-" River began.
"Ssshhh." Gentler than ever before, the TARDIS materialized soundlessly. Neither River nor the Doctor moved for a long moment. "Come on," the Doctor whispered.
They stepped outside and stayed close the TARDIS. They had land in what seemed like the edge of a forest.
"What-"
"Ssshh. It's 1941, the height of the London Blitz," the Doctor began, just as he had all those years ago. "Bombs are falling from the German planes on a daily basis. But that's not the only thing that's fallen. A month ago, an Chula battlefield ambulance fell to earth. A little boy died. And the nanogenes in the ship escaped. So the nanogenes attempted to fix the little boy up. But they had no idea what a human looked like. So they patch him up as best they could. But that's not all. They're trained to fix soldiers in battle, ready them for combat. And now there is a little boy who is a soldier with incredible power, ready to tear down all of Britain to find his Mommy. Because there is very little a boy won't do to help his Mommy."
"Doctor, why are you tell me all of this?" River asked impatiently.
"Because, River, this is important. Now, the nanogenes think they know what a human looks like, right? They fixed that one up, good as new." The Doctor peeked out toward the building near where they were hidden. People were moving around. He could see Jack now, trying to talk to Algae. It was almost time. "And so the nangenes went around and began converting people. First just those that touched the original boy. Now it's becoming air born."
River's eyes widened. "Doctor, if it's air born-"
The Doctor waved her off. "We'll be safe, don't worry. Now, people were dying. They weren't just being changed, they were dying. Dozens of people." On cue, an army of zombie creatures approached the older-younger Doctor, who was standing by the ambulance. The Doctor could see Rose now, and he needed to close his eyes for a moment, taking another deep breath. The day everyone lived. He was glad he was able to share it with her.
"We need to help them," River said urgently. "They're going to die." She unholstered her blaster.
The Doctor set a hand on the gun, lowering it. "Just watch."
River watched, amazed, as the older-younger Doctor figured out the mother-son relationship between the girl and the first boy. She watched, fighting back tears, as the girl hugged her son. She watched, breathless, as the nanogenes fixed the boy. As the older-younger Doctor reprogrammed them. As he shouted out with manic glee, a daft smile on his lips that stretched them to his large ears, that 'everybody lived.' Watched as the pretty blonde hugged him, as the handsome man hugged him, as everyone celebrated.
"Sometimes, in a great long while, everybody lives," the Doctor said softly. "Even Jack, who Rose insisted I save from his exploding ship," he added as Jack stopped the bomb from deploying.
And River knew that, if she lived long enough, she would see the day that everyone lived. It was a good day to look forward to.