His sleeping habits had changed a lot over the past few years - more regular hours, longer and better-quality sleep. Deeper sleep, too; six years ago, he would have been woken by even the subtlest of disturbances in his surroundings, ever on his guard, his brain never truly switching off. But now, unless he was actively working a case, Sherlock was fully able to embrace the joys of a good night's sleep. The only irony, of course, being that the past few years – and further significant changes in his life - hadn't exactly been conducive to that.

All this meant that there was absolutely no warning before the assault began.

"It's Christmas! it's Christmas! it's Christmas!"

"Mummy! Daddy! We're awake!"

This alarming verbal tirade was accompanied by a physical one that was no less startling. Sherlock just had time to cover his more delicate parts before a small human landed on top of him, quickly followed by another, slightly smaller one. Something inanimate also landed perilously close to his head, soft with random pointy corners sticking out of it, and he could feel another heavy-ish thing being hauled over his legs and onto the bed.

His eyes darted to the alarm clock by the bed, and then Sherlock winced.

"I thought I made it clear to you two reprobates that Christmas doesn't begin until after seven o'clock," he mumbled thickly.

He heard Molly chuckle, felt her shifting, with some difficulty, across the bed to be closer to him. Her left hand slid under the covers to rest on his stomach, her nose tucking into the crook of his neck.

"Two problems with that," she murmured, so that he could feel her smile against his skin. "They can't tell the time, and even if they could, they don't care."

"Can we open them now?" the older boy asked, completely ignoring his parents.

"Please?" his younger brother added.

The things that had been unceremoniously hauled onto the Holmes marital bed were, of course, two very large, bulging stockings. They hadn't seemed quite so gargantuan when he and Molly had filled them the night before, but Sherlock reluctantly shifted into a half-sitting position to avoid being brained by their older son swinging his stash of presents.

"Careful of Mummy, both of you," Sherlock warned, as the two children bundled under the covers next to Molly, fighting to get in beside her.

He helped Molly into a sitting position, stretching his left arm around her shoulders and feeling that familiar warm contentment as she leaned against him. Sherlock's right hand automatically snaked around to rest on her belly, which now almost needed a postcode of its own, let alone a bed; next Christmas, there would be a third stocking to think about, and in approximately six weeks, another new Holmes to welcome into the world.

As they watched their sons excitedly delving into their stockings, and the bed becoming increasingly strewn with torn wrapping paper, Sherlock felt Molly's hand coming to rest over his, her wedding ring bumping over his knuckles. It had been a frenetic few years, and in most respects life was unrecognizable. Two (and a half) small additions to the household, a legal commitment to each other alongside the one that was more deeply, implicitly understood, and of course a change of domestic address.

As soon as he had walked through the door of the Victorian townhouse, Sherlock knew that Molly would love it – and also that she wouldn't mind that it was, at the time, a crime scene (thankfully, the murders in question had been committed elsewhere). It hadn't escaped his notice that, over time, the house had more and more come to resemble the one he had dreamt about that night, as Molly found time to add touches that she liked. Now, it had become a pleasing jumble of old and new, his things and her things, baby equipment and endless plastic toys piled in with medical curios and souvenirs from particularly memorable cases.

There was just the odd moment, usually when he was alone, where Sherlock would turn the corner and expect to find Mary Watson in his hallway. He should probably have found this distressing, but after the initial twinge of sadness, it would always leave him with a strange sense of peace and calm. It would remind him to say something nice to John, or to invite he and Rosie over to dinner.

"That was a big one," Molly smiled, with a gasp, taking Sherlock's hand and shifting it around to the side of her bump. "Are you ready to do it all again, Mr Holmes?"

Sherlock snorted.

"Not really, but I expect we'll cope. We could always sell one of the bigger ones."

"Um, you were the one who barged into my house that Christmas Eve saying you wanted babies," Molly retorted with a smile. "Amongst other things."

She had a point. And everything he told her he wanted on that night he now had – including the houseful of gaudy Christmas decorations (draped everywhere, so that he walked face-first into them wherever he turned), and festive traditions that made absolutely no sense to him (their children followed Molly's family tradition of sending their letters to Father Christmas up the chimney).

And that was not all.

"Nicky!" their older son cried, suddenly rolling off the bed and skittering across the floor in bare feet to the bedroom door.

"Wait, no, not the-"

But it was too late - the door was opened and ninety pounds of bloodhound came lumbering into the room. The dog was immediately embraced by their five-year-old, who was without doubt viewed by the Holmes canine as its primary master. Nicky (short for Copernicus, Molly's hilarious joke at Sherlock's expense) was supposed to be a noble, tenacious tracker dog, a valuable addition to Sherlock's case-cracking arsenal – but in reality, he was hopelessly soppy and preferred life as a spoilt family pet. On the few occasions when Sherlock did bring him along on a case, Nicky had generally risen to the occasion - but he was slow to get going, easily distracted by passing females, and often needed pushing. So not unlike John, in many respects. But also like John, once he was in Sherlock's life, he wouldn't have been without him for the world.

"So now we're all here," Sherlock sighed, watching the present-related carnage continue.

"Mm, not quite," Molly replied, helping their younger son with a particularly tricky piece of Sellotape.

"Toby's got more sense," he said, picturing Molly's cat enjoying the peace and quiet of the living room. These days, he was so aged and infirm that Sherlock wasn't even allowed to shoo him off his chair.

Molly turned in Sherlock's arms, taking his face in her hand and giving his cheeks an affectionate squish.

"You shouldn't complain," she added, placing his hand on her belly again. "After all, Christmas has been pretty good to you."

Molly was, as always, completely right. Sherlock still remembered in brilliant detail that first Christmas Day, and the days and weeks that followed it; when alone with Molly, he had quickly turned into a delirious, lovestruck idiot, completely addicted to her company and her touch. And he'd kept in mind the advice imparted to him by the Mary of his subconscious – he let the other stuff happen in its own time, and Molly did keep him right. More than right.

With a parting kiss to Molly, Sherlock extricated himself from the bed, ruffled his sons' curly heads and padded down the hall to the bathroom. Call of nature taken care of, he returned to the bedroom bearing mugs of tea, nearly tripping over the dog on his way to the bed – no chance of drinking the tea safely, though, with all of the frenzied activity.

No sooner had Sherlock eased himself into a seated position under the covers again than their younger son launched himself full-force towards him, this time Sherlock reacting slightly too late to prevent a small, bony knee making contact with his most vulnerable area. He took a sharp intake of breath, catching Molly's look of concern tinged with amusement.

"Daddy, was that your testimals?" the three-year-old asked, with a tone of scientific enquiry.

Now Molly was sniggering.

"You realise, Dr Hooper, that the only benefit to teaching them the proper anatomical terms is that they can now – near enough - correctly name the afflicted body part while they maim me?"

Molly leaned into him, checking to make sure their sons' attention was on their presents.

"If it's still sore tonight, I'll kiss it better," she whispered, with a devilish smile.

Probably just as well he wasn't holding his mug of tea at that point.

"And you said we shouldn't get each other anything for Christmas…" he replied, matching her smile with a roguish one of his own.

They always did end up getting each other something for Christmas, though, whatever was said beforehand; something small and idiosyncratic, and usually come across by chance. From where he was sitting in bed, Sherlock could see last year's present from Molly – a leather-bound first edition of The Practical Handbook of Bee Culture, printed in the early part of the twentieth century and unearthed by Molly at the Southbank Book Market. He had read the whole book almost in one sitting, and was now seriously looking into whether there was enough space at the bottom of the garden for a starter hive.

The book sat on the shelf beside a small, lacquered wooden box. On Boxing Day, six years earlier, while Molly was still asleep in his bed at Baker Street, he had finally found the courage to go looking in his wardrobe for that unopened present, still wrapped in red paper and gold ribbon. The oak box that he unwrapped, with its hinged lid, contained an antique field microscope; brass, with a small selection of Victorian-era slides that still bore the original owner's handwriting in archaic, swirling script. To this, Molly had added a collection of new slides, which she had assembled herself, containing recent lab specimens she thought would interest him. When she had woken up that Boxing Day morning, Sherlock hadn't hesitated in expressing several years' worth of delayed gratitude. And even though he had examined each slide many times in minute detail over the years, he still went back to them from time to time, because…well, just because.

"We should get moving, Sherlock," Molly said, stretching a little. "Or else they'll all arrive and we'll have nothing to feed them."

Getting moving was now easier said than done for Molly, and Sherlock had queried her wisdom in offering to host Christmas dinner at their house while nearly eight months' pregnant, but she's insisted it would be fine – and it meant that their sons could play with their new acquisitions while they got everything ready. In a few hours, John and Rosie would arrive with Mrs Hudson and Lestrade, and the mayhem would really begin in earnest.

A few more minutes spooned around Molly in the warmth of their bed was just what the doctor ordered. Perhaps the boys would play quietly on the floor for a little while – miracles had happened in his life before, after all…

"Who wants to go with Daddy to the park to try out your new pocket magnifiers?" Molly asked brightly, earning a look of mild horror from Sherlock.

"What?" Molly smiled, all casual innocence. "They were your idea."

"Yes, so you said, but you were a willing participant, if I remember rightly."

Molly rolled her eyes.

"I was talking about the magnifiers, not our gorgeous children."

Sherlock sighed, pouting slightly and earning an indulgent look of mild sympathy from his wife.

"Yes. Because they keep stealing mine."

On more than one occasion, he had turned up at a crime scene, unfurled his investigation kit and found a blank space where his magnifier should have been. One time, he had found in its place his younger son's toothbrush, something that John, Lestrade and half of Scotland Yard found far more amusing than he would have liked.

"Detection can be an indoor activity, too," he pointed, glancing outside at the decidedly frigid weather conditions. "I've solved countless cases without even leaving my chair…or my bed."

"I know, I know, you're a very brilliant man," Molly replied, patting his hand fondly. "But Nicky needs a walk anyway."

Sherlock groaned into her neck, feeling her puff of laughter against his temple.

"Oh, stop being a Scrooge," she told him, drawing his face out of her neck to place a kiss on his nose. "It's Christmas, and everyone in this room loves you very much."

And he would give his life for any one of them in a heartbeat. Sherlock tipped his face up to catch her lips with his before she could pull away, kissing her with as much passion as felt appropriate in front of the audience present. (Although the dog had, unfortunately, seen much worse, on one occasion when the bedroom door was accidentally left open. Sherlock still didn't like to think of it).

"Urgh, no kissing!" their older son piped up, momentarily distracted from hitting his brother with a foam-rubber pirate cutlass.

Molly giggled, and Sherlock look up, narrowing his eyes at his young doppelganger, who held his gaze with a defiant grin.

"No kissing, eh?" Sherlock said slowly, pulling back the edge of the duvet. "Well, young man, let's see how you feel about…this!"

And with that, he dived over the covers, hearing a shriek of gleeful surprise just before he pinned his son down and started to plant big, wet (and bristly) kisses all over the little boy's face. Within seconds, the younger boy had joined in, throwing himself on top of Sherlock and laughing with delight. Although he couldn't see her at that moment for the tangle of torsos and limbs, Sherlock heard the wonderful, musical sound of Molly's laughter – it never ceased to amaze him that he could be the source of her happiness.

There had been moments when he still felt like an impostor, felt as though the floor could open up underneath him and rob him of his domestic bliss. And it was domestic bliss, he couldn't deny it. The past six years had presented him with challenges unlike any he'd previously known, had forced him to dig deep within himself for resources he'd never before tapped - but every time he'd been tested and could have failed, he didn't. Because it mattered, and because he no longer had to face any of it alone – Molly was his lodestar, his constant, his anchor, his comfort. She diffused his brooding with terrible jokes, and reminded him – convinced him - that he had as much worth as a man as he had as a puzzle-solver.

Ten minutes later, he was thunking down the stairs in search of the dog's lead, and it hit him again. He stopped halfway along the hall, and looked over his shoulder. There was nobody there, of course, but it was that same sense of a benign presence, almost as though he could feel someone smiling behind his back. Sherlock stood there for a long moment, just allowing himself to think and feel. Even if she wasn't really out there in any form, however intangible, she had still played a considerable part in his happiness – and if she was, Sherlock hoped she knew she would always be welcome in their home.