A/N: Sorry folks, but this chapter will be a bit shorter than the others, because it was the first smutty chapter in the M rated version. Hope you still enjoy it, and I look forward to your reviews.

It happened the night Wills had his first sleepover at his grandparents' house. Molly and Sherlock drove in her car with their son chattering excitedly to them the entire time about all the things he and Sherlock's parents were going to do that weekend. Molly and his father would stay for dinner, then head back to London.

It had been three weeks since the dinner at Baker Street, three weeks during which Sherlock and Molly had spent zero time alone together - both a blessing and a curse, at least in Molly's opinion. During that time they'd behaved with complete circumspection, not so much as trading meaningful glances over Wills' head on the few occasions they met. But the growing heat between them was so palpable, the sexual tension so all-encompassing, that it was no surprise when things finally exploded into passion after they said their good-nights and left Wills to enjoy his weekend in the country.

They'd fully intended on driving back to London. At least, Molly had fully intended on driving back. But when the door to Sherlock's parent's house shut behind them; when they'd seated themselves in her car; when she'd turned to ask him...something she'd long since forgotten...the look in his eyes had stopped the words before she could do more than part her lips. They remained parted in an 'o' of surprise and he'd taken immediate advantage, closing the small gap between them and kissing her like a man starved for the oxygen in her lungs.

Waiting the length of the drive to London seemed impossible after that. Instead they drove to a small inn about twenty minutes away. Once there they barely made it to their room before he had her pressed up against the door, the two of them trading fierce, needy kisses as they fumbled the clothing from each other's bodies. From there it was only a few steps to reach the king-sized bed and tumble onto it together.

It was as amazing as Molly remembered it; Sherlock was just as passionate as he had been in uni, and she was more than happy to show him how much she'd missed being in his arms. Hours later, passion temporarily sated, they fell into sleep, tangled in one another's arms.

She awoke at some point, thirsty and chilled where Sherlock wasn't holding her, but when she tried to get up his arms tightened around her and he nuzzled at her throat. "Stay," he mumbled.

"Thirsty," she said, giving him a quick kiss. He let her go with what felt like a great deal of reluctance, and she could feel his eyes on her as she crossed to the small en suite. She paused at the door, turning to give him a quick smile before entering and shutting the door behind her.

oOo

Sherlock rolled onto his back, staring at the ceiling and wishing desperate for a cigarette. He had no idea how Molly felt about smoking, but had the vague thought that asking her about it tonight wouldn't be the best timing. Of course, their falling into bed together only six weeks after reconnecting with one another was the epitome of bad timing, but he couldn't bring himself to regret it. He only hoped she wouldn't, either, in the cold light of morning. Or was she even now staring at herself in the mirror, wondering what kind of mistake she'd just made?

He'd started to work himself into a panic when the bathroom door clicked open and she reentered the main room. She was still completely naked, drinking thirstily from a glass of water. When she saw him looking at her, she smiled somewhat self-consciously and held the glass up. "Want some?"

"Yes," he replied, never taking his eyes from hers as he stood up and crossed the room. He could tell by the sudden widening of her eyes that she understood very well that he wasn't talking about the water. Their kiss was urgent, desperate, as full of longing as if they hadn't kissed in years rather than hours. He swept her into his arms, glass and all, and kissed her giggles into moans and sighs as he plucked the glass from her hand and placed it on the bedside table. Then he settled her onto the bed, and set about showing her that he was just as eager for her as he had been before.

This time when they reached their mutual completion, instead of being sleepy he felt energized, and he could tell Molly felt the same. She smiled at him as he stroked her hair. "Thirsty again," she said, her voice raspy, her lips kiss-swollen and her expression one of extreme satisfaction.

He groped for the glass, handed it to her then watched as she knelt up, then stood and took the few steps needed to reach the bathroom door. She paused, then glanced down at him with an impish grin. "Shower?"

He didn't need to be asked twice.

The next morning, right on schedule, Molly panicked. Sherlock could see it in her eyes as soon as she opened them and saw him lying next to her. He, of course, had been awake for over an hour, just watching her sleep, enjoying the ridiculously domestic situation - and knowing exactly how she would react. First her eyes widened; then she scrambled upright, holding the sheet to cover her breasts, brushing her tangled hair from her face. "Oh my God," she moaned, "what did we do? I can't believe I...Sherlock, we have to leave, we have to go back to London right now…"

"We have to do no such thing," he said firmly as he reluctantly sat up, allowing the sheet and duvet to fall to his lap. Her eyes wandered down his bare chest before snapping up to his face, her face going a pleasing shade of pink. "Molly, this wasn't a mistake; neither one of us was impaired, it was what we both wanted. So stop panicking."

She took a deep breath and let it out slowly, never taking her eyes from his. "Right," she said after a minute. "We're both adults, we're both unattached - you are unattached, aren't you?" she asked, panic clearly trying to take over again.

"Not anymore," Sherlock replied, pulling her into his arms for a lingering kiss. "As we've already discussed, I'm rubbish at relationships, but I find I want to try with you, Molly. And I can't imagine you don't feel the same."

"It won't be easy," she said. "We have Wills to think about. What if things don't work out?"

"Then we return to simply co-parenting," he said with a shrug. "And whatever it is that I end up doing to mess things up between us…"

"I might be the one messing things up," Molly objected, but Sherlock shook his head.

"No, the odds are definitely stacked in favor of it being me. The point I'm trying to make is, if I DO mess things up between us, we'll both have to try not to let it affect our son."

Molly nodded slowly. "Agreed." She blew out a breath and gave him a tentative smile. "So. What now?"

"Now," he said as he rolled them so he was on top of her, "we continue exploring the physical part of this new relationship."

Molly showed her agreement by pulling him down and kissing him very, very thoroughly.

A kiss that was interrupted by the sudden ringing of her mobile – and seconds later, his.