I wanted to do something nice for Christmas. I wanted a sweet one shot with Sherlock and John. So, I hope that you enjoy

John held a sprig of mistletoe over Misses Hudson's head as she opened the door for him. The doctor giving the older woman a kiss on the cheek and a cheery smile before making his way up the stair to the flat that he had once shared with his friend. The presents that he was holding nearly spilling from his arms, as he dug around in his pocket to retrieve his key.

The ex-army doctor had always been a sucker from Christmas. Always had a soft spot for the silly season, and this year would, he was sure, be the best. For not only did he have Mary and Rosamund, but now he also had his sister.

(Y/n) Watson had not long before received an honourable discharge from the British Army after many years of distinguished service. The younger Watson, just like her brother also attaining the rank of Captain. Yet whereas her brother had been a medical doctor serving with the Fifth Northumberland Fusiliers, (Y/n) had been part of the Intelligence Corps. John really not sure where his younger sister was from one moment to the next. The older Watson having to confess, that despite the fact that he was quite aware that (Y/n) could take care of herself, he had always worried about her. And given her job and whirlwind life, it had been far too long since the two siblings had seen one another. (Y/n) unable to attend his wedding to Mary due to her posting. The former captain only recently having met her niece. So, when John had opened his inbox one day to find and email from his sister to inform him that she would soon be getting discharged, the doctor had quickly replied, telling her that she had to come to London. That she had to meet Mary and their daughter. That she should find a place close to him and they could get to know one another again. And that was where Sherlock had come in.

John wasn't sure that it was a good thing to begin with, moving his much-loved sister in with Sherlock. And in truth, he had thought that persuading the younger Holmes into giving his old room to his sister until she could find something of her own, would have been a lot more difficult. Yet to his surprise, after Sherlock had gotten over the annoyance of not having deduced that his friend had a younger sibling, he had quickly agreed to having (Y/n) take her brother's place. John sure that it was the fact that his sister had been an intelligence officer, that had swung it. And now, well, now things seemed to be going quite well between the new flatmates, in at least the respect that (Y/n) hadn't strangled Sherlock for being and insensitive ass and Sherlock hadn't called him in the middle of the night demanding that he take his sister out of his flat.

If he was honest, he would have liked for (Y/n) to have found a place of her own by now. John knowing that she liked her own space and privacy just like Sherlock did. Yet he also knew that there was probably no place safer, in a way that is, than being with the consulting detective.

"(Y/n)..........? Sherlock................?" John called out, as he finally managed to push his way into the flat. Cursing at himself as some of the presents that he was juggling dropped onto the floor. The doctor smiling broadly, as he placed the rest of the gift onto the table and looked around the room, finding that the flat was in one piece and very, very clean. His sister obviously having a good effect on Sherlock. The living room decked out in tasteful decorations that suited not only (Y/n), but also Sherlock. A large tree standing next to the roaring fireplace. Its branches decorated with very expensive looking baubles. The only thing missing, the ornament for the top of the tree.

"John." A voice came. The doctor's smile getting even broader, as his sister poked her head around the kitchen door. A chuckle leaving his lips as she appeared fully. Her apron and nose covered in floor.

"Hello (Y/n). Cooking something.............?" John enquired, as he found himself enveloped in a hug.

"Oh, er, yeah...............mince pies. I am trying to make them like mum used to, but I am sure that I am missing something. Sherlock insists that it is cinnamon, but I tried it and it still isn't right." (Y/n) explained, as she brushed the flour from her brother's coat and the Christmas sweater underneath, before turning her attention to herself. The white powder floating into the air, as pulled the apron from around herself and threw it onto his old chair.

"And speaking of Sherlock...........where is he?" The older Watson enquired, as he handed his sister the presents that he had bought with him. Watching as she placed them at the base of the tree.

"Well, he insisted that mince pies required Brandy custard. And even though I said that I would make some, he explained that he knew a place that made the best Brandy custard in London. Then before I could say anything else, he grabbed his coat and disappeared out of the door. He's been gone for about two hours now. I think when he said it was in London, what he actually meant, was it the best custard in Cornwall." (Y/n) chuckled, as she took a seat on the floor next to the fire, and John took a seat in Sherlock's chair.

"Yeah, you'll be lucky if he comes back before it goes dark outside. And even then, he will have forgotten the custard." John replied. The doctor sure that he hadn't seen his sister this happy since they were young. Sherlock seeming to be having quite the effect on (Y/n) too. John not sure whether that was a good thing or not.

"The tree looks beautiful, sis. But what about the top...............?" John continued. Knowing that the fact that the tree was not complete, would probably be driving his younger sibling, crazy.

"Oh, yeah. I had bought a star. Just something simple. But the great consulting detective said that he had something. That he would take care of it. I have a terrible feeling that he has fashioned something out of the body parts that I keep finding in the fridge. I am sure that by the time that he has finished, everything on the tree will be replaced and it will look like a scene from a horror movie in here.................." (Y/n) explained. Both Watson's jumping as the door to the flat was thrown open. The two siblings watching as in came Sherlock. The detective calling out as he pulled his dark coat from his shoulders.

"(Y/n)! (Y/n)!...................." Sherlock called again, before turning around and seeing that both Watson's were looking up at him. Sherlock making his way further into the flat, seeming to completely ignore John, as he moved over to where (Y/n) sat before dropping to his knees. The doctor's brows furrowing, as he saw a smile, a real smile spread across Sherlock's lips.

"This is for you............." The consulting detective continued, as he handed (Y/n) a box. Gesturing from her to open it. (Y/n)'s eyes growing wide as a beautiful star was revealed. An inscription on the gift reading, "For our first Christmas and all the rest to come." The younger Watson handing the gift to her brother, before throwing herself into Sherlock's arms. The hug making it obvious as to why (Y/n) hadn't moved out yet. John realising that this was going to be a very different Christmas and he and Sherlock would be having a few words later. That, and had indeed forgotten the custard.