It was still dark, not yet five in the morning, when Sherlock opened his eyes, then blinked at the man who was smiling at him. He wanted to ask, needed to know what he was smiling about, then was afraid to ask, and then realised he had spent an entire night, well, at least six straight hours, not thinking, not even trying to think about thinking, but asleep, next to the only person who ever meant more than -
"I couldn't sleep."
Sherlock's voice sounded rough and odd to his own ears as he rumbled out, "did I - I'm not used to sleeping, let alone with someone next to me, if I -"
John shook his head and smiled at him again, the kind of smile that made him wonder what he would do if he moved closer and took a chance, he blinked at him once more, then reached out to pull him closer. He paused, for just a moment, then brushed his lips over the smile, then pulled away and put his fingers to his lips, as if it would help him to memorise what the smile had felt like, tasted like. He looked into John's darkening eyes, and cleared his throat. "Sorry. No. Not sorry. Not a bit sorry, I needed to know, just once what your smile - what?"
"Deduce, Sherlock, you can see everything about a perfect stranger, and yet, you don't have a clue about me. Odd, that."
Sherlock nodded, and found the words he could think to say were too little, and at the same time too much, so he shrugged, then drew John into a kiss that told him everything he ever needed to know. A kiss that asked him to stay, a kiss that thanked him for his patience and his light, the light he never knew he needed to fight the endless darkness that was finally no longer his enemy.
"Yes," John whispered. "Of course, yes. It's early yet, let's go back to sleep."
Sherlock pulled John into his arms, then waited until he was settled against his shoulder to ask, "is this -?"
"It's perfect. You're perfect." John pressed a kiss over an old scar, then closed his eyes, and was soon fast asleep.
There were cases, there were always puzzles he could work on, experiments, data to accumulate, but at that moment, he realised he didn't care about anything, but holding onto the man who snored lightly in his arms.