Things don't change, not that Sherlock truly expects them to. Mostly, the same routine rotates in his daily life; intimacy is his only addition.
They still take clients, still work cases, still work with Lestrade, still humor Mycroft on certain occasions. Nothing within their flat changes either. The skull still sits on the mantle, less judgemental after they'd finally had sex; the kitchen is still overrun with experiments, most of which John still fusses about; John still has his bedroom, using it when Sherlock has plans to stay up all night, ignoring it when they have sex and fall asleep together; they still drink tea, John still conducts his blog, Sherlock still plays his violin at the worst time of the night; they keep right on being them as if nothing has changed.
While most things haven't, the changes that have happened are stark and clear.
John professes his love with ease, never faltering, warm and pleased in his truth, and Sherlock always feels the reward like a stroke to his mind. He's still trying to work out why John telling him those trivial three words means so much, but he doesn't let the mystery hold him back from returning the idiotic sentiment. When handed to him, Sherlock has no choice but to return the words to John, simply because the sweetness of them causes him to ache in a way he hasn't felt in years.
Sex, of course, is less of a problem than he imagined. While messy and uncertain, it is quite pleasing to do. In fact, having sex with John practically saves lives. If there is a case that's proving to be difficult, Sherlock can drag John off to the bedroom and return with a thriving mind, nearly solving the case in minutes every time. And sometimes, they have sex just because they want to, just because John wears Sherlock's favorite jumper, just because Sherlock mocks John's favorite program on the telly, just because Mrs. Hudson teases them about being right about them all along when she comes around with tea and biscuits and a playful smile. There's a freedom in sex, and Sherlock enjoys it far more than he has ever expected to.
They stumble, at first, when faced with what they are to each other. Molly says married with an air of a woman working very hard not to eye up someone else's husband; Sherlock and John work together to find her a suitable man. Lestrade just ribs them about it relentlessly, mocking and cajoling good-naturedly until Sherlock firmly confirms that yes, John does the fucking and makes the Detective flush bright red, never to tease them again. Mycroft offers to officiate the marriage papers he's had drawn up since he first ever spoke to John - which John is mystified that Mycroft hadn't been joking then - but they both agree to decide on that on much later date, Sherlock because he knows John would want a real wedding, and John because he knows Sherlock wouldn't. They'll get there eventually.
Mrs. Hudson, unsurprisingly, provides them with the only answer that fits. She taps their cheeks, pinching slightly in joy, and declares them her boys, saying that they'd always be Sherlock Holmes and John Watson to her regardless.
In the end, they settle with that. They're just them, living in 221B Baker Street, solving cases, having arguments that they both love and pout about in equal measure. Out in public, in the eye of the media, they don't go out of their way to make a statement. But John doesn't refrain from holding Sherlock's hand when he gets too riled up or frustrated, and Sherlock has no qualms about announcing that they have to leave and have sex very promptly. Naturally, the media explodes over it, and John resigns himself to ignoring the newspapers around the city.
Sherlock is pleased to find his life almost exactly the same as always, only improved by the new additions.
One morning, something feels different.
John's up earlier than him, which never happens when they fall asleep together, and he's sitting in his chair when Sherlock enters the sitting room. His eyes are distant, cloudy with some faraway thoughts, mind working far harder than an idiot's should. He doesn't look up when Sherlock enters, doesn't greet him, doesn't say anything, and Sherlock is immediately discomforted by the stillness.
“John?” he greets quietly.
John does not look at him when he says, “It's been six months, did you know?”
Sherlock immediately files away in his mind, recalling what happened six months ago in mere seconds. Ah, his return. “Yes,” he says, because he does know.
“I remember thinking, before you were back, that the next six months were going to be as hard as the first, that they'd go by and it would be a year, and I still wouldn't understand how to live without you.”
“This date is important to you. Are we going to make it our anniversary? John, you know I don't really do sentimental things such as-”
“Sherlock,” John says, blinking and finally looking at him, “you were gone, dead, and I… I wanted to follow right along after you.”
Sherlock moves over to the couch, settling on it and crossing his legs. “You wouldn't have; you knew I wouldn't have wanted that.”
“I know. I would have… kept on going, I suppose. A year would have come, then two, maybe three, and I still would have ached,” John admits quietly.
“You might've found someone,” Sherlock suggests, fighting the urge to curl his lip in disgust.
John smiles slightly, looking down at the twisted fingers in his lap. “A nice woman, blonde maybe, very pretty, would be stern with me. Margret, or Sylvia, or Mary.”
“Seemingly normal and kind. You would have fell for her easily,” Sherlock says softly, frowning out the window at the thought. “She would have helped you heal, like I have before, and you'd want to marry her. By then, I'd have come back in your life.”
John looks up, scoffing. “I would have been so angry with you, Sherlock. You'd have popped up out of nowhere, without warning, probably in the middle of the very date where I'd propose, because you're a cock with impeccable timing.”
Sherlock looked over at him in surprise. “You would have been miffed at my return?”
“More that miffed, Sherlock, I would have probably attacked you worse than I had when you actually returned. It would have been even worse because I'd be ready to take the final step with someone I love when the supposedly dead love-of-my-life just randomly shows back up. I would have hated you as much as I loved you.”
“You would have stayed with her.”
“Yes. We'd have lived together, happily, having kids, and you'd have been the best man at my wedding.”
“We'd have gotten too close at some point though.”
“Oh, sure. Probably on stag night, when we'd drank too much. I'd have stopped controlling myself so much, probably touched you intimately, maybe even let you know that I wouldn't mind if it would go further. But you wouldn't act on it.”
“No, I wouldn't have. I wouldn't ever compromise your happiness, John, no matter my own.”
John gives him a sad smile. “I'd still have loved you, and you'd still have been in my life.”
“Of course,” Sherlock agrees. “The woman, your wife, she'd have insisted on it. Stern, as you said, and probably perceptive as most of the woman you've seeked after before, she would have known how important I was to you. She would love you, truly love you, so she'd want you to be happy, even if we weren't always on the best of terms.”
“She'd probably turn out to be a bloody criminal, or a spy, or an assassin, knowing me,” John chuckles weakly, shaking his head. “That'd be just my life.”
“I'd figure it out; she'd shoot me,” Sherlock says, lips twitching in faint amusement.
John frowns. “You'd live, obviously. Me and her would have our issues, but if she was good - really good - I'd forgive her, though there would always be tension. Something would happen, something terrible, and it would come down between you two.”
“You wouldn't have to choose,” Sherlock tells him seriously. “We'd choose for you. Whomever you could live without, that's who would be gone.”
“That would leave me right where I am, maybe with a child, maybe not, but ultimately… with you.”
“I guess it's a good thing I called Mycroft for help with all this, isn't it?”
John just smiles. “Sherlock, we're always going to end up together, aren't we? No matter what we face, no matter what world we're in, no matter who else exists… it's always going to be us.”
“Quite frankly, I have little evidence suggesting otherwise,” Sherlock admits, shrugging shamelessly.
“One day, when Mrs. Hudson is gone, when we can't chase criminals anymore, when we've decided to rest, we'll leave this place and raise bees, and you'll be the crotchety old man who talks harshly to the youth and only softens in my presence. And one day, we'll die together, all at once, and that's going to be okay, because we'll have some other life to fall in love with each other all over again,” John muses softly, face radiant with joy.
Sherlock grins. “Maybe I'll be an angel this go around. You can be a non-believer.”
“Sounds like an adventure.”
“With the two of us, it always is.”