Sherlock's encounters with Death began young.
Now, he's an old friend.
Sherlock is five. He's looking for bugs to collect in the trees behind the house. He's not actually supposed to be here on his own, but Mycroft wouldn't come with him, and he was bored.
He sees something under a tree. A bird. Sherlock knows the specific kind, because he read that bird book of father's three weeks ago. But he can't seem to remember it now, because looking at it, the bird isn't moving and Sherlock is worried. He lays down on the ground next to it, carefully looking for any sort of movement. The bird's chest is still rising and falling. Alive. Sherlock examines it. His wing looks funny. He bets it hurts. Sherlock did that to his arm already, but it got better. Sherlock lays there for a while, just watching it, until it stops moving entirely.
Sherlock looks up to see it is dark, and says a whispered goodbye to the bird as he heads back to the house with wet cheeks. It must have rained.
Sherlock saw lots of dead and dying animals after that one. He never killed any of them, even though some of the boys from school told stories about how Sherlock liked to catch frogs and pull their legs off, or trap bugs beneath magnifying glasses and watch them burn. He would never do that.
Sherlock is eight. He is very clever for eight. Perhaps even cleverer than Mycroft was at eight. But for the life of him, he's not clever enough to fix mummy, or even figure out why every time he sees her his stomach gets all funny and his head hurts. He even looks it up in Mycroft's biology books and goes to the library, but none of them explain what is wrong or how to fix it.
Mycroft tells him he can't fix mummy, that mummy is going to die, and that he should go spend time with her. Sherlock thinks Mycroft is lying. Mummy won't die.
Sherlock watches as she dies. He sees it, when no one else does. He watches life slip out of her, both slower and faster than he ever thought possible.
Sherlock is 21. He is lost and broken, drugged and emancipated. He doesn't really know where he is, besides at the bottom. His thoughts are hurting him, and the drugs numb them. This way, his thoughts are scrambled, and they can't work together and gang up on him. There may be better ways, but for now, he is satisfied.
Until Death comes calling. At first, Sherlock thinks he is dreaming, or still high and hallucinating. But as he watches what Death does, taking the boy next to him, that's really all he is, just a boy, no older than Sherlock, barely needing to shave, he sees Death for what he really is. Greedy, unbiased, eager.
Death looks right at him. Sherlock sees his reflection in his eyes. It terrifies him.
So when Mycroft finds him the next day, and insists he goes to rehab, Sherlock only pretends to argue. He never wants to be that close to death again.
In his line of work, Sherlock saw a lot of dead people. Dead was fine. There could be nothing done for dead people. They were now evidence, to be used to for solving the crime of how they died, and who killed them. Death was no longer present, but had come and gone. He was fine with this.
He didn't know how John did it, especially in Afghanistan, sometimes being forced to watch as Death came and stole someone from right beneath his hands. John was a good doctor, very good, but he couldn't always win. Sherlock knew that hurt John. He knew that John had seen Death so many times that he was no longer surprised by his face. He knew that Death had tried to come for John, but John told him to piss off, that he wasn't done.
Sherlock knew he couldn't look in Death's eyes. Which was why John was the doctor, and Sherlock only visited people after Death and been and gone.
Sherlock is 34. Death is coming for him. He has been shot. Again. But he senses this is different, worse. It doesn't hurt. At least, not like it should. He feels the blood, his blood. It's warm. It shouldn't be leaving him. He likes it where it was. He wants to scoop it up and keep it. Not in the fridge though. John wouldn't approve.
And Sherlock knows Death will come for him. Knows that Death has never been too far behind him all his life. Knows that he has been so very lucky, shot three times previously, stabbed twice, too many concussions to count, poisonings, and so many other times where Death had been but lingering in the wings, just waiting for his curtain call. Not yet though. Not yet.
But here comes Death, smiling, for Sherlock. It's Death's turn, finally. So Sherlock closes his eyes and waits. And waits. But Death does not visit him, there is no embrace, and the pain is not stopping, but only getting worse.
He opens his eyes, and there is John, battling with Death, battling with Death for him, and winning. John beats Death down and sends him away. Tells him not to come calling for a very long time. Because John Watson is the man who stares down Death, and sometimes loses, but mostly wins.
When Death came for John, he could no longer stare. His eyes had long since failed him. Sherlock knew that Death had waited, far longer than he should have, a good long while. But Death seemed to understand John Watson, being sent off more than once by this man, and waited until he was invited to return. So Sherlock watched as Death came calling, and John Watson welcomed him in.
Sherlock could have sent him away. But he didn't. So he watched John die, watched Death take him. He watched, just like he had too many times before, and swore he never would again if he could help it, as Death took John, and he was gone, both slower and faster than he ever thought possible.
And after Death took John, he looked at Sherlock. He could have sent him away. If he really wanted to, if he really tried. But Sherlock was not just Sherlock. He was Sherlock Holmes of Sherlock and John, the detective and his blogger. He was Holmes of Watson and Holmes.
So he could have sent Death on his way, telling him to come back when he was supposed to in a couple of years. He decided against it.
So he greeted Death with open arms and welcomed his embrace.