Their band of four made its way out of the door and around the east wall and into what was always the formal garden, laid out with perfect mathematical precision by their mother (and then inevitably undermined by their father's rather haphazard gardening efforts). The large expanse of lawn had been cut, and would surely be the perfect venue for games come the summer. Not that Mycroft was ever one for games, particularly of the outdoor variety - but he got the feeling Sherlock and Molly's children would be different. At this point, William and Teddy were running in circles around the grass, giggling, and apparently confused over who was chasing who.

Sherlock beckoned them to follow, and as they all turned the corner again, Mycroft was greeted by a sight he hadn't expected.

"You kept them?"

Sherlock, now helping Teddy with the toggles on his coat, looked up and followed Mycroft's gaze to the collection of fictitious headstones standing in the grass.

"I couldn't see a reason not to," Sherlock replied. "They were never about death or loss. And they felt as much a part of this place as the house itself."

Teddy ran off to try to catch his brother, and Sherlock straightened up, running a hand through his mussed hair.

"I'd...I'd like to show you something..."

He reached into his pocket for his phone, flicking through the screen views until he found what he wanted, and then holding the device out to Mycroft.

On the screen was a close-up photograph of a large, flat stone, engraved. Mycroft zoomed in slightly to read the words:

"And a brave lad you were, and smart too…and a finer figurehead for a gentleman of fortune I never clapped my eyes on."

"From Treasure Island," Mycroft murmured.

Sherlock bowed his head slightly.

"When we had the old well properly sealed up, I...I wanted to do something," he said. "This was Molly's idea. It's set into the ground under a tree near the well."

Like Eurus' room, Mycroft knew that the final, awful resting place of Victor Trevor was going to be one of the most difficult things for Sherlock to address during the renovation. Nothing could ever be enough, but this was a modest, heartfelt tribute.

"Daddy! Teddy fell in the dirt and now there's dirt in his nose!"

Any melancholy reflection was immediately abandoned, and Sherlock furrowed his brow before striding across the grass to inspect the extent of Teddy's soil-inhalation (the sort of thing, Mycroft noted, that his brother took in his stride these days).

"Well, that's one way of collecting soil samples, young man," Sherlock said, smiling at his son. "But I think we'll be having something much better to eat very soon." Teddy was now in his arms, pulling a face and blowing raspberries while Sherlock wiped earth from his mouth and nose. "Let's go and get you both changed."

Back in the house, Christmas Day played out, and Mycroft allowed himself to be swept along, his nephews largely taking centre stage. Lunch was excellent, and it was followed by more opening of presents (he was right - no surprises), and, eventually, drinks.

When time and circumstances allowed it, Mycroft took the opportunity to study his surroundings in more detail. The house was remarkable, and something that could only have been possible because of Sherlock's relationship with Molly - because the future was now important to him; because he was ready and able to confront and make peace with his past.

Mycroft observed Sherlock and Molly during the course of the afternoon; five-and-a-half years after Molly had forced the words out of him, after she'd confessed them herself, it was clear that Sherlock was more besotted than ever. The little touches, the private language of glances and smiles, the good-natured bickering and teasing - it all pointed to a deep, abiding love that Mycroft knew Sherlock didn't take for granted for a moment. Later on, on a mission to obtain yet more cups of tea for his parents, Mycroft came across his brother and sister-in-law in the kitchen; Sherlock's arms were wrapped loosely around Molly's waist, while they took full, unhurried advantage of the mistletoe hanging from the beam above their heads.

Mycroft hung back for a moment, unseen; as they broke apart, Sherlock ducked low and murmured something to Molly that caused her to laugh, her forehead falling against his chest. It was still with a flash of guilt that Mycroft recalled how vehemently he had once fought to keep Molly Hooper out of his brother's life. As it turned out, Molly had unquestionably given Sherlock life.

An hour later, his nephews were in their pyjamas, sandwiched between their grandparents (both dozing) on the sofa and watching an adaptation of A Christmas Carol, which seemed to involve rodents breaking into song on a regular basis. Mycroft slipped out of the living room. He quietly climbed the stairs again, and was still questioning his actions as his hand turned the knob of his old bedroom door. Once inside, he stood silently for a long moment, trying to recall how everything used to be configured - his bed along the wall to the right, his desk under the window, his record player on the top of the drawers beside the wardrobe. When the house was set alight, his bedroom had still been full of his childhood possessions - things that would never be replaced when they moved into the new house. It was, as Uncle Rudy had remarked firmly, time to grow up.

But, like the rest of the house, he conceded that this room did house good memories, too. Unwrapping new LPs ordered from the tiny music shop in Horsham; sitting on the floor and reorganising his books by whatever system he currently favoured; practising his lines for the next school play.

The soft knock on the open door behind him made Mycroft spin around. Molly was standing there, smiling apologetically. They both tried to speak at the same time.

"Sorry, I-"

"My apologies-"

Mycroft gestured for Molly to go first. Over the past few years, the two of them had developed a pleasant, comfortable friendship, albeit after a slightly uncertain start. Fiercely protective of Sherlock, Molly had - understandably - been taken aback by the unravelling Holmes family secrets, and Mycroft's role in guarding them. He was very fortunate, he knew, that his sister-in-law was a woman of rare perception and understanding.

"I didn't mean to sneak up on you," Molly said. "I was coming upstairs to finish getting the bedrooms ready. You...you are staying tonight?"

Mycroft thought about the overnight bag in the boot of the car, his get-out clause. He didn't get the chance to confirm or give his apologies before Molly spoke again.

"Anyway...there was something I wanted to give you," she continued. "But...well, not necessarily in front of everyone, I suppose."

He hadn't noticed before, but she was carrying a small shoebox under one arm, which she then shifted so that she was holding it in both hands.

"I'm still not sure this is the right thing to do, that you…" - she paused, her brow furrowed as she fixed her gaze on the box - "...but I hope it's okay. Sherlock thought it would be."

It was clear that this was no Christmas present in the conventional sense. Mycroft nodded once, encouraging her to continue.

"When the builders first started work, when they were clearing the site, they started to find things," Molly began. "Just little things mostly, but we asked them to put everything to one side. This...these things were found in your old room."

Molly tentatively held out the box to him, and Mycroft reflexively took it. It was light, but he could feel small objects were rolling around inside it.

"You, um, you don't have to look at it now," she said quickly. "Or, you know, at all - if you'd rather not. But, well, they were your things, so…"

Slowly, Mycroft eased the lid off the box. What could possibly have survived the fire? He had, of course, carried out one search himself, without his parents' knowledge, but had recovered nothing from his incinerated bedroom of worth or note. His fingers moved among the objects in the box, the pace of his heart increasing.

Marble chess pieces, two of them - a pawn and a knight. A small soapstone paperweight. His old House Captain badge from school, twisted but still intact. Something that he eventually realised was the brass eyepiece from his telescope.

Mycroft lifted out a small tin box with a lid, dented and with the original design barely recognisable. But he did recognise it.

"That was actually under the floorboards," Molly said.

"I know," he replied, with a slight smile.

"Sherlock had never seen it before," she added.

"It was my secret hoard," Mycroft said, looking up. "Nothing illicit," he elaborated, when he saw Molly's questioning look. "Sweets, mostly. The occasional chocolate bar. It's probably fair to say that I had...a weakness."

Molly's face broke into a smile.

Mycroft levered open the hinged lid, half expecting to find melted and solidified boiled sweets and chews welded to the bottom of the tin.

"Hm," he said, raising his eyebrows at the sight of the empty box. "Must have been peckish."

Molly gave a short laugh.

"They, um, they found some things of Sherlock's, too," she said, her hand roaming over the small bump of her stomach. "I'd like to do something with them, although I can't think what just yet. You're...you're welcome to leave your things, too, if you'd prefer. It could be - I don't know - some sort of a project. You can think about it, though."

Mycroft replaced the lid on the shoebox.

"I will," he told her. "Thank you."

Molly nodded.

"Well, I'd better go and finish the rooms," she said. "I'm not sure who needs to get to bed first - the boys, or your mum and dad."

Now in their mid-eighties, his parents could almost fall asleep mid-conversation if they were comfortable enough. Just resting their eyes, they insisted.

His sister-in-law made to leave.

"Molly," Mycroft said, clearing his throat.

She stopped, turning to face him again.

"I wanted to say...that you and Sherlock have done a remarkable job with the house," he said, realising just how much he meant the words as they left his mouth. "I'll admit that I didn't know what to expect, was a little...hesitant. But it's...well, it's quite incredible. You should both feel proud."

His sister-in-law's face spread into a smile, and she thanked him.

"To be honest, I never would have imagined myself doing anything like this," she said, tucking a strand of her long, loose hair behind her ear. "But I could see how much it meant to Sherlock to at least try - and to your mum and dad, too, I think."

Mycroft nodded in agreement.

"They seem delighted with it."

Sherlock and Molly had originally, Mycroft knew, offered to rebuild the house for his parents' benefit, but they wouldn't hear of it - they were settled where they were, and had gladly signed the deeds over to Sherlock.

"Well, London's still going to be home for the time-being," Molly continued. "But Sherlock's keen to come down at the weekends, when neither of us are working. You and Alicia are welcome to come and stay here anytime you like, though, whether we're here or not."

"Thank you," Mycroft told her. "And thank you for today - for dinner, and, well...all of the things for which I haven't adequately expressed my gratitude. For my brother. For forgiving my sins...and my misconceptions."

When he looked up, Molly was regarding him, her lips pulled tightly together. Then, unexpectedly, she took two steps towards him and drew him into a gentle hug. It came so far out of nowhere that Mycroft just stood there stiffly for a couple of seconds, before placing an arm gently around Molly's shoulder. As they stood there, Molly turned her head just far enough so she could whisper, "I promise I won't make a habit of this."

Mycroft laughed softly, and she stepped away, pulling down the sleeves of her jumper, which, on closer inspection, he realised was covered in microscopes, DNA double helices and other scientific symbols.

"I was going to wheel out the mince pies in a few minutes, if you've got room?" Molly said. "William and Teddy were involved in the baking, so I can't completely vouch for the hygiene, but Sherlock ate one this morning and he's still standing. Well, he was ten minutes ago."

"It's a risk I'm willing to take," Mycroft replied. "I, ah, I just need to fetch something from the car first."

"Oh," Molly replied. "Good."

She smiled, and as she turned and then disappeared into Sherlock's old room, Mycroft realised that Molly knew exactly what he was doing - had known all along. But it wasn't, he reflected, a case of him being so transparent - it was merely that his sister-in-law happened to be very good at this. Alicia had a similar talent. He and Sherlock were, Mycroft acknowledged, extraordinarily lucky.

Carefully placing the shoebox on the mantelpiece in his old bedroom, Mycroft set off to collect his overnight bag from the car.

Improbable though it had seemed earlier that morning, it was time to settle in and make merry.