"I think that was the one," Sherlock declared, his breath a little ragged, before collapsing back on the pillow.

Molly giggled, rolling her eyes probably more to herself than at him, making way so that he could snuggle into her side, his head coming to rest on her chest.

"Oh, really?" she said, humouring him. This was starting to sound familiar now. "And what makes you so sure?"

"Felt decisive," he replied, his voice rumbling across her skin. "Resolute."

Again, Molly snorted with laughter; if they were going to talk about how it had felt, she would have worked her way through several other more adulatory adjectives before arriving on those particular words.

"So, you, um, told the indecisive sperm to stay where they are and make way for the ones with more focus and ambition?" she asked.

"Something like that," he murmured, bringing his hand up to rest it flat across her stomach. Suddenly, he lifted his head to look up at her.

"Wait, are you sure you don't want to adopt a more elevated posture? Allow gravity to provide a natural advantage?"

Molly snorted.

"No!" she told him, raking her fingers through the curls at the nape of Sherlock's neck. "I'm very happy where I am, thank you."

"Hm," he replied. "Me, too. Although, you should at least lay still for around thirty minutes anyway. You just have to watch a video of salmon to know how problematic and self-defeating it is to try to swim upstream."

He said it with a completely straight face. Dear god.

Molly tilted his chin up towards her and planted a kiss on lips.

"Ten minutes, Sherlock."

"Twenty?"

"I will lie here for fifteen minutes," she said, fixing his gaze with hers. "One, because I have no interest in starting the week with a urinary tract infection, and two, because Mrs Hudson will be back with William in less than half an hour and I'd rather it didn't look so blatant that we've just had sex."

It was Sherlock's turn to snort this time.

"What else would she think we'd be doing with a child-free hour?"

Molly frowned, feeling herself blush inexplicably. Mrs Hudson was incredibly straightforward and completely un-prudish, but it still felt to Molly like she'd be laying her sex life bare (so to speak) to her nan.

"Um, cleaning, maybe?" she offered, not buying it for a second herself (although god knows the flat could use it).

Sherlock scooted himself up the bed, making a sound that sounded a lot like scoffing.

"Would you rather have been cleaning, Molly?"

Molly jabbed a finger lightly in his side, refusing to even dignify that with an answer. Sherlock leaned in, planting a kiss on her neck and nibbling his way northwards, across her jaw, and homing in on the spot just beneath her ear that he knew bloody well always got a reaction.

"Anyway," he mumbled. "I believe Hudders' last words to me were 'You two have fun' and something about knocking loudly when she gets back. I believe she was under no illusion."

Oh well. Perhaps she could 'conveniently' be in the shower when their landlady arrived back with their son.

Molly turned her head and dragged Sherlock's mouth up to hers, capturing it in a brief but intense kiss. When they broke apart, he barely moved, instead staring directly at her, heavy-lidded.

"More please," he said, his voice a low whisper.

Molly raised her eyebrows.

"I thought I was supposed to be lying stock-still for the next fifteen minutes?"

Sherlock cocked his head.

"I can try and work with that."

She lightly shoved him again, prompting one of Sherlock's wonderful, crinkly smiles. Everyone insisted that William had her smile, but smiles were made with more than the mouth alone, and William definitely had his father's eyes. Watch out, world.

"Go," she told him. "If I'm doing this, then you're getting me a glass of water and the path journal I left in the living room."

This was her fairly hopeless attempt to keep up to speed with her field of expertise while spending her days with a seven-month old baby, who seemed to be capable of functioning without regular naps. She had started to write a proposal for a paper, but whenever she theoretically had a moment to develop it – or the opportunity to browse a professional journal – she would inevitably glaze over within about five minutes. Who were these women who spent their maternity leave learning a new language or studying for an MBA?

"And could you at least do a quick tidy of the living room?" she asked. "Just…it would make me feel better."

Sherlock heaved a sigh at this, as he hauled himself into a sitting position.

"Do I have to put clothes on first?"

"Do you want Mrs Hudson to suffer heart failure?"

Sherlock snorted.

"Nothing she hasn't seen before, Molly," he replied.

"Well, let's not chance it, hm?" Molly grinned, snaking her hand across the bed to rest on his thigh. "Besides, I think she'd like to be around to make a fuss of baby number two."

At that, Sherlock's face broke into a grin of his own.

"- whenever he or she comes along," she added.

Almost as soon as the words left her lips, they were followed by a surprised yelp, caused by the sensation of having not one but two pillows quite forcibly wedged underneath her hips by a consulting detective with a very determined look on his face.

"Hey, what the-" Molly protested, somewhat too late, she realised, given that Sherlock was now sitting back on his haunches to admire his handy work.

"Subtle change in gradient," he said by way of a response. "It can't hurt."

"Maybe not, but it isn't that comfortable, Sherlock," she fired back. "You try lying here for ten minutes with your pelvis pointing at the light fitting."

"Fifteen minutes. And I would try it if I thought it would have any bearing on our chances of conceiving."

Molly felt her expression soften a little. This really meant a lot to him. It meant a lot to her, too, but for Sherlock, adding another number to their family seemed to have turned into a mini crusade; she just hoped it wouldn't veer into an obsession.

"Besides," he continued, looking around distractedly. "This probably wouldn't even be necessary if it hadn't been for Mycroft's bloody prison-camp searchlights."

Molly gestured to the handle of the bedroom door, where she had quite skillfully managed to fling his pants a short while earlier (she had even made him pause in his ministrations to admire her sporting achievement). Sherlock shuffled off the bed to fetch his underwear.

"Yeah, um, that did kill the moment a little," she admitted.

In the aftermath of Mycroft's wedding, Sherlock had managed to persuade her that it was time to provide William with a sibling – and that it was necessary to begin doing so in the seclusion of Mycroft's summerhouse. Or at least it had seemed like seclusion – until the security floodlights came on at a very pivotal moment.

"Not the only thing it killed," Sherlock huffed, a swift glance south as he adjusted his pants.

Although it had quickly become clear that Mycroft hadn't 'released the hounds' and that there weren't government agents camouflaged in the shrubbery, they had decided to take things back to the guest room. Except that Sherlock's squeamishness about having sex with William sleeping nearby meant that rather than the bedroom itself, it was actually the en suite bathroom, with its harsh lighting and inconvenient lack of flat surfaces.

There had been other efforts, too, in more conventional surroundings – but despite still being a bit erratic after William's birth, her period had arrived almost bang on schedule about two weeks' later. Molly had more than half-expected it anyway (two 'one-shot' pregnancies in a row would be borderline freakish), but the disappointment had been painted all over Sherlock's face, even though she could see he was trying to rally himself for her benefit.

"C'mere," Molly said, beckoning him back across to her. She kept motioning until Sherlock was leaning far enough across the bed for her to take his face in her hands.

"Sherlock, whether or not that was 'decisive' or 'the one'," she said, taking in his querying expression. "It was still lovely, and that's important, too."

The furrows that marked his forehead relaxed a little, and he nodded.

"Yes, it would seem foolish to turn one of my favourite pastimes into a chore," he replied, dipping his head and allowing Molly to capture his lips with hers.

"Just one of?" she queried, eyebrow raised.

"Locked-room murders are pretty high up there," he replied, tilting his head to one side. "Would probably have to add discrediting psychics as well – always extremely satisfying, particularly as, mysteriously, they never seem to see it coming."

Molly narrowed her eyes at him.

"- although those things carry the distinct disadvantage of not getting to see you naked," he added briskly.

"Nicely saved," Molly grinned, patting his cheek. "Although you're now thinking of how me being naked might be compatible with those things, aren't you?"

Sherlock gave a quick cough.

"Couldn't possibly comment," he said. "Instead, I am going to fetch you the requested glass of water and the aforementioned publication that neither of us actually believes you intend to read."

She managed to hit his arse with a well-aimed pillow as he stooped to recover his trousers.

"I am definitely going to read it," she retorted. "What if Mike asks me if I've read anything recently, and all I can say is The Very Hungry Caterpillar?"

"I dislike that story," Sherlock muttered, pulling on his trousers. "The incorrect usage of 'cocoon' rather than 'chrysalis' is extremely misleading for the developing infant. Anyway, Molly, I highly doubt that Stamford is going to interrogate you on the latest advances and debates in the field of pathology during what I understand is termed a 'keeping in touch day'."

Molly caught him wrinkling his nose at the very term. Git.

"He might," she mumbled in response, pulling the duvet up to her elbows.

"Molly, Stamford couldn't interrogate the lunch menu in the Bart's canteen. He's one of those nice people."

Again, she saw the nose-wrinkle and an accompanying look that suggested – despite fatherhood and impending matrimony - Sherlock still found the world a very puzzling and exasperating place.

"I know," Molly sighed. "And I know that it will probably be mostly cups of tea and photos of William, and maybe meeting new faces around the place, but still…"

How to express this conflicting gamut of emotions to someone who rarely suffered crises of confidence in their work, had never (to Molly's knowledge) had a proper job with proper colleagues – let alone a boss - and who would certainly never face snide accusations of 'baby brain'?

Sherlock stopped in the middle of fastening his trousers, and looked up, his expression softening around the edges as his eyes met hers. He swallowed, his gaze dropping for a second before rising again to meet hers.

"It will be fine, Molly," he said, his voice a little softer than before. "You know it will. You were the youngest specialist registrar ever to be appointed by Bart's, you have published papers in some of the world's most eminent medical journals, and quite frankly you are the most intelligent and capable person, I know – and I'm including myself in that statement, in case that wasn't clear."

Molly smiled; she knew Sherlock didn't believe in flattery, so to him this was mere statement of fact.

"And there's absolutely no need to worry about our son," Sherlock continued. "William and I have a very stimulating and edifying day planned."

It would be the first time that Sherlock had truly looked after William for a full day, single-handed, but in all honesty, that wasn't a concern. Well, it was a bit of a concern – not his ability to care for their son, more his notions of what might constitute 'stimulating and edifying'. Molly was fairly certain Sherlock didn't have baby yoga or a 'sing and sign' class in mind.

"Sounds, um, fun," Molly replied, diplomatically.

"Indeed," Sherlock said, distractedly. He was looking for something.

"Top of the wardrobe," Molly pointed, suppressing a laugh.

"Oh, for god's sake, woman!" Sherlock exclaimed in mock exasperation, rescuing his shirt from where she'd flung it. "Why must you turn sex into some kind of fairground game?"

"Do I win a prize?" she grinned, waggling her eyebrows at him.

"Sorry, no time for that with Hudders on the way," he replied. "Besides, you've still got eight minutes remaining. Knees up, Molly."

Molly opened her mouth to protest, but was met with a wink and the sight of Sherlock sweeping out of their bedroom door, still buttoning his shirt.

Yeah, no danger at all of this veering into an obsession.