Molly looked over at Sherlock again, giving him her full attention. But before she could ask her first question – how did he feel about being so unexpectedly presented with a ten-year-old son he'd never known about – he spoke first. "He's very bright."

She smiled proudly. "Yeah, I know. I should probably have him in more advanced classes – he's especially good at chemistry and maths, did he tell you? – but I want him to stay with kids his own age."

"Does he…get on well with them? The other kids, I mean?" Sherlock asked, sounding a bit wistful. Molly wondered if his own childhood had been difficult or lonely.

"Oh, yes, he's one of the most popular kids in his class," she said. "Sometimes he's a bit too popular, if you know what I mean; spends more time chatting up his mates than he should, gets a bit, um, high-spirited, but he's a good boy and doesn't get into too much trouble."

Apparently Wills hadn't held back on anything when he and Sherlock chatted…he'd told his father (that was going to be a difficult term to get used to saying!) about cutting class to meet him today, about the time he'd managed to replace the dead frogs they were supposed to dissect with live ones that he'd meticulously sedated as a prank on his science teacher, and about quite a lot of other things he'd done that Molly had been rather hoping to forget.

Sherlock surprised her when he said, "You named him William. May I ask why?"

There was something in his voice, the slightest catch, which caught Molly's attention. She responded to that hesitation instinctively, wanting to reassure him that it was all right, that she wasn't going to hide anything from him, that she wanted him to know about his – their – son. "You're his father, Sherlock," she said. "You can ask me anything you like about him! He's named after my father and my Mum's dad – William Henry Hooper. Why?" She made another attempt at humor. "Is William not one of your favorite names or something?"

Sherlock shrugged. "I suppose you could say that," he replied, but before she could do more than bristle at his words (what was wrong with 'William', it was a perfectly lovely name!), he lowered his voice and added, "It's just that…it's my name, too. My first name. My full name is William Sherlock Scott Holmes."

"Oh." Molly stared at him blankly. Somewhere in the cosmos the Fates were giggling their ancient, bony arses off right now. She'd not known the name of the boy she'd had sex with, yet had ended up naming their son after him anyway. The giggle started off small, then morphed into a full-bellied guffaw as she bent over, laughing harder than she had in years.

After a moment she realized Sherlock was laughing right along with her, his deeper chuckles sounding as sort of counterpoint to her own higher pitched giggles. "W-well, that cinches it," she finally managed to gasp out. "No one will believe me when I say I didn't know you were his father before today!"

"I think my brother might accuse you of having dastardly reasons for 'hiding' Wills from me all these years," Sherlock replied between continuing bursts of laughter.

That last comment served to sober Molly immediately, reminding her of all the things she didn't know about this man. "You have a brother, then," she said. "Just the one?"

"One remaining brother," he replied, sobering as well. "Older. Mycroft." He made a face, as if the name – or the brother – was an annoyance. "Our younger brother, Sherrinford, died a few years back." The closed-off expression on his face warned Molly that that was not something he wished to go into, and she showed her respect for his privacy with a simple nod of understanding.

"I have a sister, her name's Grace, she's two years younger than me, married and has a daughter, Louisa, she's two years younger than Wills and they get along, oh, about half the time." She smiled fondly at the thought of her eight-year-old niece. "Mostly when they're not competing over who plays the violin best."

Sherlock gave her an odd look. "He plays the violin?" Molly nodded. Sherlock flexed his fingers, looking down as he said, "So do I."

The coincidences were piling up, the cosmic joke turning into a Shaggy Dog story the longer Molly and Sherlock spoke. "Oh," she said, beginning to feel a bit overwhelmed, then: "Does your brother play as well?"

Sherlock pulled a face that reminded her so strongly of Wills when he found something distasteful that she nearly gasped. "No," was all he said, causing Molly to wonder if he and his elder brother didn't get on well.

She told him about her mum, about her father's illness and why it had taken her so long to discover her pregnancy. Sherlock listened attentively, nodding now and again, and willingly spoke of the rest of his family when she fell silent. "Both parents living, house in Sussex, they're out of the country at the moment but they'll be thrilled…that is, I hope you don't mind if they…" He stumbled to a stop and just looked at her as if uncertain how to proceed.

Molly knew exactly how he felt. "Of course I don't mind. Wills is a very outgoing little boy – well, not so little any more, I guess," she added wistfully. "Anyway, he was already so excited to meet you before he knew…before either of us knew." She tried a smile and knew it was much closer to a grimace but plowed on. "Now that he knows you're his father, you have no idea how over the moon he is about it."

"Oh, I might have a small inkling," he replied with a smirk, and suddenly Molly was taken back ten years, seeing the traces of boy he'd been in that smile. All he needed was a messier head of curls and a bit of stubble and a few less lines around his eyes…and all she could see, suddenly, was the two of them naked, in a stranger's bed, moving against one another with a fierce urgency, and felt the blush climbing up her cheeks as she tried to remember what it was she'd been saying before her mind wandered down such an inappropriate mental byway.

"Um, yes, I suppose he was pretty enthusiastic when he met you," she agreed, toying with the end of her braid, a nervous habit from her childhood that she'd never outgrown. "Anyway, all I meant to say was that I'm sure he'll be excited to meet your family…his family…his other family…oh, bollocks!" she exclaimed as she, found herself stumbling over her words the way Sherlock had only moments earlier. She gave him a helpless look. "This is just so…I wasn't expecting any of this when I got up this morning, you know?"

His answering smile was wry, just a curl of the lips. "Yes, I rather think I do," he said.

"Thank you." Sherlock looked confused at Molly's hastily spoken words, so she elaborated: "For not…running away screaming when presented with a ten-year-old miniature version of yourself. For not accusing me of anything nefarious, for not…blasting me for not trying harder to find you."

"How, exactly, would you have gone about it?" Sherlock asked drily. "Taken out an advert, asking for the chap who shagged you at a party while he was high and you were extremely drunk, to come forward and accept responsibility for the child you were now expecting?" He shook his head at the absurdity of the idea, which Molly couldn't disagree with. "We didn't even have first names or initials to go on, Molly; I'm a deductive genius and I can't even say I'd have been able to find you had I known I needed to do so at the time."

There was no modesty in his voice, but there was no bragging either; he said the words 'deductive genius' in the same matter-of-fact way she might describe herself as a human being. "The only thing I told you about myself was that I was studying chemistry, and as I recall, that was only in the context of making a rather bad joke about the joint I was in the process of lighting up – and to answer your next question, no I don't do drugs anymore, haven't for years – while you ran about in a panic redressing yourself after we'd had sex."

She felt a flash of relief that he willingly volunteered the information that he no longer did drugs, a question she would have felt uncomfortable asking him but would have done so anyway since it was clear he wanted to have some kind of relationship with Wills – but colored a bit at the bland way he spoke of their previous relationship, brief as it had been. But honestly, what did she expect? It had been meaningless sex, a way for her to blow off steam and for him to possibly do the same. She hadn't exactly asked him his reasons at the time. "Why did we?" she found herself asking, curious to hear his take on it. "Have sex, I mean." She felt her blush spreading down her cheeks but tried to ignore it; it was silly, she was a grown woman who had a child, for God's sakes! A child with this very man.

He waved away her question with an annoyed frown. "Why do you think? You were attractive and drunk and I was high and you kissed me on impulse – something I could tell you'd never done before – and that made you even more attractive. No simpering attempts at seduction, no coyness; you wanted something, and you went for it. The fact that the something you wanted happened to be me was very satisfying to my ego; I'm a man, after all, and when an attractive, unattached woman throws herself at me – at least, when I was at uni and still bothered with things like that – I willingly catch her. Caught her." He pulled a face. "Sorry, I seem to have run into some tense changing problems there. But you understand what I mean." He cocked his head to one side, examining her closely. "You're not hurt by my saying that," he pronounced after a moment, sounding faintly surprised. "Why not? I've been told I'm far too blunt, and I know that I'm rubbish at expressing myself when it comes to sentiment, and any number of people have assured me that discussing intimacy with a sexual partner – or even a former sexual partner – can often stir up unexpected emotions."

Molly was pleased to have surprised him by her reaction – or rather, her lack of reaction – to his spot-on analysis of their shared time together. "Why should I be hurt, or upset? It was the truth. I'd much rather you were honest with me than try to spare my feelings by offering me some rubbish lie about how special our time together was. I have to admit, I was surprised you even remembered me," she confessed, lowering her eyes to where her hands were fidgeting with one another in her lap. She consciously forced them to still, to rest together, interlacing her fingers tightly before returning her gaze to meet his. "I'm not exactly, well, memorable." She pulled a face. "Sorry! That sounded like I was trying to get you to reassure me or something. Forget I said it."

His face was entirely unreadable for a long moment; just as she was beginning to wonder if he was having some sort of delayed shock reaction, he blinked and nodded. "Forgotten. Now. I know you have questions for me; ask away, and I promise to be completely honest. And if for some reason I can't, I promise to tell you so."

They spent the next hour quizzing one another on the paths their lives had taken since that fateful party. She found out that Sherlock lived in a flat on Baker Street, only about an half-hour's tube ride from Molly and Wills' home, which he shared with a flatmate – a former army doctor who'd served in Afghanistan and had been invalided out, who was also a friend of Mike Stamford's – and lived what seemed to be a fascinating and somewhat alarming life. How a son would fit into that life was something neither of them brought up.

He deduced a great deal about Molly without her needing to tell him things, impressing her quite a bit. He knew she and Wills had a cat – fur on their clothing, simple when you looked for it, but who bothered? He also told her quite confidently that he knew she was working long hours in order to save up enough money to buy a house, that she hoped one day to move to the suburbs more for her son's sake than for he own, and that she had no intention of asking for any kind of maintenance from him – but that he planned to make arrangements for just that as soon as possible.

Molly tried to protest, but he steamrolled right over her, insisting that it was the least he could do. "But you haven't even asked for a paternity test!"

He gave her a look (one she would grow very used to in the near future), a look that said, plain as day, 'Don't be stupid.' His next words confirmed her interpretation of that look as he said, "Honestly, Molly, even Stamford saw the resemblance. But if you insist, I'll accompany you back to the lab so you can take a DNA sample. I suppose I'd better do it anyway," he added, rolling his eyes in a melodramatic fashion. "Or Mycroft will be after me day and night until I do."

Oh, there was definitely some animosity there; Molly was curious, but kept her questions to herself. She and Sherlock had been talking for over an hour, and that was more than long enough to keep Wills waiting – and to keep Mike, she thought guiltily, busy with temporary babysitting duties. Right now she needed to get her son home, call her mother and sister and have a family meeting to discuss this unexpected development. Thank God Sherlock didn't seem completely aghast at the idea of having fathered a child ten years ago; however, for all Molly knew his seeming acceptance of the situation could simply be due to shock, just as she knew her own reaction was likely to set in once she was home. The easy camaraderie and rapport she thought they shared could be as insubstantial as soap bubbles, here now, gone an instant later.

Besides, it wasn't her relationship with Sherlock that was important, it was Sherlock's relationship – whatever it might turn out to be – with Wills that mattered. "So, um, should we exchange mobile numbers? Do you want to know where we live, should we be talking about schedules and visits? It's fine if you don't," she added in a rush as she fiddled with her mobile. "It can wait, I mean, you just found out about him today and I don't expect you to make any kind of a decision right this min…"

"Molly." Sherlock sounded slightly annoyed, and she gulped and closed her mouth as she gave him an inquiring look. "Do you always ramble like this, or is it just when you're nervous?"

Instead of upsetting her, his terse question caused her laugh again. "Oh, a bit of both. I tend to go on more when I'm nervous, but yeah, this is me, how I am most of the time. Except, well, worse than usual today. But I think I can be forgiven under the circumstances."

He had the grace to look abashed at her implied rebuke, mumbling something about everyone reacting to stress in different ways as he pulled out his mobile. She read out her number, he gave her his, and Sherlock helped her to her feet, keeping a guiding hand at the small of her back as they left the break room.

Wills was in the path lab, peering interestedly into a microscope while Mike lectured him on the properties of the sample he was examining. They looked up when Sherlock and Molly entered the room. Molly smiled brightly and thanked Mike for looking after Wills. She quickly explained what she and Sherlock needed to do, blushing lightly at the prospect of asking for yet another favor – although she'd hardly asked for the first ones Mike had granted, she still felt she was taking advantage of his good nature. She tried to apologize, he brushed it off, and Wills looked positively ecstatic at the thought of being subjected to a DNA test. "That's wicked, that's the coolest thing ever!" he gushed, bouncing around the lab like an overexcited terrier while Molly set everything up.

Fifteen minutes later the swabs had been taken, the tests sent for analysis, mobile numbers and addresses had been exchanged, and Molly was finally ready to take her son home. She was a bit taken aback when Wills turned to Sherlock and said, "Is it all right if I tell people? Or do you want to wait until the tests come back?" His eyes positively lit up as he added, "Or is too dangerous for people to know I'm your son? Do you have a nemesis or an arch-enemy or anything like that?"

Sherlock laughed, a delighted sound, reached out and ruffled Wills' dark curls, so like his own, as he replied, "No, it's fine, tell whoever you like. As long as it's all right with your mother, that is," he added, giving Molly a grin.

She couldn't help responding to that smile, feeling a sudden rush of desire as he caught and held her gaze. God, they'd had sex once, just once, so why was it suddenly all she could think about? "Well, let's hold off until we've talked to your Gran and Aunt Grace," she said lightly. "We'll deal with telling anyone else after that, right?"

Wills nodded, looking a bit disappointed (he'd probably planned to blog about it or at least send out a mass email to his friends), but his expression swiftly returned to one of utter bliss as Sherlock told him he could call him, anytime, day or night – or email, if he so desired. He promised to answer any questions Wills might have – with Molly interjecting that maybe he could pass those questions by her first, to which he and Wills both responded with equal scowls but both reluctantly agreed to.

Then it was over, the first meeting between father and son, which had gone far smoother than Molly could ever imagine, if she'd ever bothered to imagine such a thing. She'd expected to live the rest of her life without ever seeing Wills' father again, and now had to readjust her world view to include Sherlock Holmes, world's only consulting detective and deductive genius, as part of her son's life.

Dinner, she reflected, was going to be very, very interesting tonight.