It felt like they had run halfway across London, though John knew that wasn't really the case. 'Case. God. Never should have taken it on,' John thinks. Because now they're on the wrong side of the Russian mafia, with not one, but two hitmen after them. Finally, Sherlock stops, and John leans up against a nearby wall, just trying to catch his breath. After a moment, Sherlock turns to face him, putting his hand on the wall and leaning in. John tilted his head back slightly, looking up at Sherlock. "You know, this wasn't how I was planning to spend my weekend off."
"Oh?" Sherlock asked. "Well, you may want to take that up with our pursuers."
John chuckled a bit. "Well, at least it isn't boring." He sobered again almost immediately, tilting his head down. The situation wasn't funny. The men after them were frighteningly good at what they did, and the odds of both he and Sherlock coming out of this alive were not looking good. 'No,' he thought. 'Stop thinking like that. Focus on getting through this.'
Sherlock leaned in closer, letting his hair fall forward as he looked down at John. "John, I-"
John raised his hand to Sherlock's chest and cut him off before he could say another word. "Don't. Just… don't." Because John knew Sherlock, and while he may not be a deductive genius, he knew exactly what the other man was about to say. And he couldn't stand to hear those words right now; it would make everything far too real, and far too absolute.
And John suddenly remembered, in that gestalt way that sometimes happens, a mate of his on the front lines by the name of Mike Tanaka, and how, whenever he called his wife back home, he never rung off with "goodbye." He'd said it sounded too final, and felt like bad luck. And though Sherlock's aborted statement wouldn't have shared a single phoneme, it still would have rung in the air just like goodbye.
Looking up at Sherlock, he said, "Later. When we're both back at the flat. You can tell me then." And no matter how foolishly optimistic that thought was, John clung to it. There would be a later, they would both have many more evenings at the flat on Baker Street. He stood up straight, like the soldier he'd probably always be, determined to see this through.
"Alright, John. At the flat." Then Sherlock smiled, and got that particular gleam in his eyes; and John knew he was about to suggest something dangerous, something more than a bit mad, something that would somehow have the best chance of getting them both out of this more-or-less intact. "This little game's been fun, but I think it's about time for the checkmate. Agreed?"
Sherlock's smile called forth one of John's own. He reached back to where he'd tucked his Browning, making sure it was in the best position for an easy draw. He nodded once, and said, "Agreed."