And so, life went on.
Upon beginning to share a bed, John discovered that Sherlock all but became a great spider in his sleep; at any given time she would find herself pinned down by him, all limbs and angles. The shift of harsh edges against soft curves should have been uncomfortable, but there was such a wonder in it that she couldn't bring herself to be angry whenever an elbow or a knee jabbed into her stomach or back. Instead she would carefully move the offending limb and slide back into the limber curvature of his arms, which would curl around her. There she would make her home, happy.
There was a case in Dartmoore where John nearly died of fright, Sherlock was wrong about something, and they kept a lovely mouse-eared chap from going crazy. This case would always stand out in her mind, not because of the aforementioned oddities, but because it was on this case that she saw Sherlock cry for the first time. It wasn't much, just a sort of frantic welling in his eyes as he hissed, "I don't have friends." But it reminded her that he was, in fact, human. Later, he furthered this reminder by admitting, "I don't have friends— I've only got one." Then months after that, when they'd had a spat over two dead dogs on the stairs, he pressed his lips to his ear and murmured, "You're my bestfriend, really..." and all was forgiven.
But then he jumped.
She felt his wrist between her fingers, still warm but not pulsing.
She always told herself she should have known. A trained doctor who never guessed once the man she spent every moment with could be suicidal? Stupid. Idiot, she called herself (though almost everybody is). Maybe, she thought, maybe she could have prevented it.
And it didn't help that the last thing she had said to his face was, "You heartless machine."
For weeks after Sherlock jumped, Joan sat in her chair and gazed at the wall, unbearably and irreversibly sad; she had never realized Sherlock brought her such happiness. The companionship and passion and excitement they shared had been clear to her, they were so overwhelming, but the timid contentment which fluttered in her soul had been so entwined with his presence that she hadn't quite known it existed until he died. She spent three years wondering if she'd ever feel that happiness again, even a semblance of it.
Nights eased by as she lay in his (their?) bed, trying to find his scent in the sheets, even though it had long ago succumbed to the London air which flowed in through the stupid window he'd always refused to close. She hadn't the heart to close it, herself.
More than once Mrs. Hudson laid a weathered hand on hers and murmured, "I won't be bothered if you want to give up the flat, deary," but Joan couldn't bear it. Sometimes the cavities of his absence— the dust in his beakers on the kitchen table, his violin slowly winding out of tune in the corner, that stupid deerstalker— were the only things she found purchase in. Otherwise she felt herself slipping away, like one strong gust of wind would obliterate Joan Watson and she'd be nothing but a name that came after "That fraud, Sherlock Holmes."
There were efforts on her part to reconnect with people. She attempted drinks with Lestrade and the Yarders, but it was all too quiet and polite, because there was no rude wanker saying, "Oh, trouble with the wife again?" or, "Sally! How many floors are you scrubbing?" Once, she and Mrs. Hudson invited Harry for tea; they managed to endure her company until she cried, "Come on, Joan, there's other fish in the sea!" at which point she was tossed out.
Joan did try, once or twice, to move on romantically. Blind dates. Lunch with doctors at the clinic who seemed nice enough. But she always ended up talking about Sherlock, about this one case or that one time he said that one thing, and it was obvious to anyone involved that her detective had left her unable to heal.
There were so many things she wanted to tell him. Sometimes, when the loneliness was just maddening enough, she'd take the skull off the mantle and pretend it was Sherlock. "I love you," she'd say. "I always believed in you. I would trade places with you if I could. The coffin's probably not so bad. I hated it when you called me John but now it feels stupid when people call me my real name. Please come back and call me John. I almost killed you when I found that head in the fridge— no exaggeration. You would've had to solve your own bloody murder. I love you. Your experiments were actually really interesting, I just griped about them because I complain when I'm tired, and you had me tired all the time. You made me feel like I was worth something. Did I mention I love you?"
She had so much to say.
And yet, when she received that text on that morning (I'm not dead. Let's have dinner. –SH), she was unable to say anything at all.
She rushed to the door, heaving, unsure of the floor under her and the roof above and the lungs that struggled to take in air— and she found him. He hardly looked the same man; scrappy clothes, ginger dye fading from his hair, five new scars that she could count, more age in his gaze than three years could account for. Her eyes saw him, knew it was him, but her brain choked on it, choked on please, just for me, don't be dead, choked on three years of bitter solitude. But when he whispered, "John," and touched her hand, she was kissing him, wondering at how the complimentary strain of her tiptoes and bend of his neck had never changed.
Later, she could never say how long they had kissed, or how long she had sobbed "Why!" and pummeled him with her fists. She remembered, vaguely, she symbiotic heave and sniffle of two weary souls still so in tune that their sobs came in time, one-two, one-two, like the music of a long-silent violin. She remembered feeling happiness reborn inside her, a Phoenix of pain and heat and beauty.
That night, lying trembling and teary-eyed in a bed that once again smelled of Sherlock, John whispered, "Never leave me again," and he replied, "I won't. We'll be immortal."
John proposed by accident.
They'd just chased a criminal right into a nest of police cars and collapsed, John flat on the sidewalk and Sherlock sprawled in the street. "I could marry you," she gasped.
Sherlock said, "Okay," and kissed her lights out.
She didn't realize they were engaged until a week later when he looked up from his microscope and asked, "Am I expected to purchase a ring?" She was bewildered but happy enough to just go along with it.
They separated only once, when Harry was lapsing into liver-failure. John got the call as they were poking around in a murder victim's house, and without even listening to her, Sherlock departed the scene yawping about glove fibers. She was left stranded. No cabs were present to be hailed, and by the time she had called a car and it had arrived, Harry was in critical condition. John was sure she'd lose her sister, and because of Sherlock she'd wasted what precious time there was left.
MY SISTER COULD HAVE DIED ALONE, HOPE YOURE BLOODY HAPPY
Was the only communication John and Sherlock had for two weeks. Then she got a call from Mycroft saying, "I found a liver."
She blanched, mouth hanging open a bit. "You... what?"
"Oh, you didn't know? Sherlock practically begged, it was quite spectacular."
"I don't underst—"
"My brother asked me to find a new liver for your sister, which I have done. Since presumably this was an effort to end a row between the two of you, I suppose I'll reserve the surprise I had worked up over his sudden display of emotional... entanglement."
After Harry's transplant, John kissed her goodbye and headed home, where she sat on Sherlock's lap and curled around him and whispered, "I'm sorry, I'm sorry, I'm so sorry," to which he only said, "I deserved it." She couldn't disagree.
John got pregnant and miscarried before the two month mark.
They hadn't told anyone, so it was just as well between them to pretend it had never happened. But some nights, when John was at her most wistful, she would put a hand to her belly and nuzzle her face into the crook of Sherlock's neck and whisper, "What would our baby have been like?"
And he would pretend like he hadn't heard, but as she was drifting to sleep, she'd hear him murmur, "Your deep blue eyes, my dark hair. Insufferable temperance. Would have to be a genius, naturally, maybe some kind of artist, though I've always hated artists..."
They never ended up getting married.
Sherlock hated ceremonies and John hated paperwork, so the closest they came to matrimony was the accidental renting of a honeymoon suite after a particularly tiring out-of-country case. They agreed that the setting was romantic and it would be a nice place to celebrate a wedding— then used the bed for nothing more than sleeping like a pair of bricks.
Their detective work continued until sometime in their late fifties when John shattered her knee in pursuit of a criminal. Sherlock carried her home that night (which was hard on his back, though he'd never admit it) and declared they were moving to the countryside to keep bees, never to poke into criminal business again. This was only partly true, as though they made their home among the hives, Sherlock continued detecting on the side. He did, however, make a point of staying out of the actual apprehension of the criminals whose crimes he unraveled— he had promised John they'd be immortal, and it was a promise he intended to keep.
After all, there is no such thing as Happily Ever After.
But Sherlock Holmes and Joan Watson got pretty damned close.