Warning: suicidal themes (although not explicit) and can be seen as friendship but I was leaning more on the romance side of things when writing this so if that bothers you, read at your own discretion.
He hated himself, for no matter how much everyone told him otherwise, he knew he could never forgive himself for what would always be his biggest regret; greatest mistake. The bright lights surrounded him; blinding him with their mocking and taunting hues that were relentless in their torment. The cold winter's air, oh how it punished him! It seemed that for every intake of breath, an indeterminable weight filled his lungs and slowed his walk to a crawl with each step that he took to the one place he could make peace with himself.
Christmas was all about the gift of giving, not taking and he could not think of anything else but the one thing he had come here to get, the only gift that could come close to the worth of what he alone he had taken from the world: the best person that the world had and would ever see, the one who helped to sift through the confusion and pointless trivia to see life for how it was. He used to think that he had made a fairly modest mark upon the world but that paled into significance in comparison to that of the one that had forced from this world, this life, so unjust, so unfair, by his own marked hands.
He stood on the ledge, gazing down at the world below, watching people go about their lives full of that undeniable Christmas spirit, the one thing that had kept him going through the holiday season as a child. That insatiable hope that a larger than life figure could swoop in and give him everything that he could need to keep on smiling and just enjoy life.
As he had grown older, that hope had never died, at least until the day he met him. Suddenly, Father Christmas with his long white beard and red suit morphed seamlessly into a consulting detective with untameable locks of that almost black (but not quite) colour, a long coat and elegant suits. No longer did he wish for sleigh bells ringing, nor did he yearn for the friendly 'ho-ho-ho'.
Not anymore.
Now he lived for the chase and the oh-so frequent sound of 'Oh do keep up John!'. That was all before the only mistimed bullet that he had ever fired turned his life upside down and then (for good measure), decided to drag his very soul through the fiery coals of guilt and self-loathing. Life before himno longer existed; each memory painted grey and echoing with the 'thud' of a lanky six foot body falling to the ground, dead before the expression of pain and undoubtedly worse than the pain; the heart wrenching acceptance had fully consumed his face.
He was so close now; just one step and they could be reunited.
One step.
Flying through the air to the only heaven he could ever appreciate. To him, who had given him a reason to keep smiling despite everything that the world and Moriarty seemed to throw in their way.
The indeterminable weight that had plagued him earlier was lifted, as if it had never existed, at the sound of that velvet baritone voice that he could and would recognise in a single heartbeat.
'Happy Christmas John. Welcome home. '
And indeed he was.