The first Christmas is the hardest, and Watson isn't sure why.
Holmes never held much stock in Christmas anyway, although he humoured Mrs Hudson lest she fear him an atheist, and wouldn't object to Christmas dinner if he wasn't in the middle of a case. But that aside, Holmes never grew sentimental about the holiday, as Watson did inexplicably every year. It was at this time of year that all he wanted was to be near to Holmes, to sit with him, talking for hours, by a roaring fire; to kiss in the early hours, their own world beneath the covers as though they intended never to rise.
"Doctor, I must object," Mrs Hudson says weakly, when Watson arrives at Baker Street on Christmas Eve. His hat and coat are covered with fallen snow, which is still tumbling from the dark sky, but he is indifferent to it. He just looks at her, and shakes his head at her protests, and she falls back, bowing her head. She has been instructed by Mycroft to keep the room as it is until he can "sort things out", and he sees to the rent. She hates it, because it seems to fill the whole house with ghosts, and fills Watson with them more.
He walks slowly up the stairs, his gait lopsided, perhaps because of his wound, perhaps because he's been drinking again, he can't remember. He grasps the bannister as he thinks he may fall. He eventually finds himself outside of Holmes' room. He pushes the door open and stumbles into the darkened room, the entire play grey, lit only by the light from outside, of the moon and the gas lamps.
Everything is covered in cobwebs. He tries to bat some of them away, until he sees Holmes' violin, frozen in time upon the armchair. He drops to his knees and howls for his Holmes, slamming his fist against the floor. He lies down in the papers that litter the floor and cries silently until some of the ink runs. He reaches into his pocket and pulls out a match. He strikes it and then holds it in front of his face watching the flame dance and flicker. He considers dropping it onto the papers.
But he cannot. He blows it out and curls up into the darkness once more.