"I had a really great time tonight." She giggled as she wrapped her arms around John's neck, standing on her toes to kiss him. He smiled and kissed her back. They were both completely wasted after the long night of bar hopping and were standing outside of 221B hoping things would go beyond kissing.
"Maybe we can do this again tomorrow, then?"
Another giggle and a whispered "maybe we should."
She ran her hands down his chest and to his pocket, searching for his keys, but came up empty handed. "Where are your keys, babe?"
John, confused, reached his own hand into the pocket. Nothing. He started checking the rest of his pockets and didn't find anything. "Shit. They were right here, I-"
"Looking for something, John?"
The doctor gasped and looked up at the tall figure that had appeared beside them, holding the missing object as it glowed in the half light of the late night.
"Sherlock?"
"The world's only."
"You bastard." She slapped him, but John didn't even register the pain. His eyes were fixed on Sherlock. "You lead me on! Well fuck you. I hope you two are happy together." She walked off, hailing a cab to go home and drown her sorrows in some Rocky Road ice cream.
Sherlock carefully unlocked the door and lead John inside and upstairs. The veteran was still completely shocked so he sat in his chair by the fire, waiting for things to process as Sherlock made tea.
"We're out of milk." The consulting detective had barely looked up from the glass before he was knocked to the floor by Dr. Watson's kitten rage and fist. But then, he was pinned down by a crying John Watson straddling his waist and holding his arms down.
"Where the fuck have you been, Sherlock? Three years. Three. Fucking. Years. I've been coming home to an empty flat."
"I'm sorry, John. I-"
"No excuses, Sherlock. Just… promise me that you'll never do that to me again."
"John, it was for your-"
"Promise me, Sherlock!"
The detective stared into John's eyes, seeing all the hurt, depression, sorrow, anger, guilt, and every other emotion from the past three years reflected in his gaze. But he also saw relief. Relief that his friend was home.
"I promise, John."
John collapsed, his head falling on Sherlock's chest as he broke down completely.
"Sherlock." The anguished sob broke the man's heart and he vowed to himself that this was one promise he wasn't going to break.
They stayed like that for hours (Sherlock couldn't move if he wanted to) and eventually, John fell asleep.
—-
He awoke on the floor the next morning, wondering whether the whole experience was just a dream. There was the sound of running water in the kitchen and John assumed it was whatever girl he had brought home the night before. He got up, rubbed his eyes, and started towards the kitchen. He froze when he saw the much more masculine figure of his late-well, supposed to be late-flatmate standing at the counter instead. Sherlock turned around and smiled as if the last three years hadn't happened.
"Good morning, Jo-" He was cut off by another pair of lips against his own.
"You Arse."