Disclaimer: I do not own Sherlock or anything pertaining to it or Conan Doyle's original stories except my own ideas and writing. All rights go to the rightful owners.
A/N: Sherlock's birthday is January 6 1980 so I'm saying that Mycroft's birthday is October 17th (Mark's birthday) 1976. You can read this on Ao3 where I am IzzyLightwood if you want to. :)
Did you make a list?
Of what?
Everything, Sherlock. Everything you've taken.
Wherever I find him, whatever back alley or doss house, there will always be a list.
I was there for you before. I'll be there for you again. I'll always be there for you. This was my fault.
It was nothing to do with you.
A week in a prison cell. I should have realised.
Realised what?
That in your case, solitary confinement is locking you up with your worst enemy.
You're in deep, Sherlock, deeper than you ever intended to be. Have you made a list?
Of what?
Everything. We will need a list.
May 13th. The first time Mycroft realised that he may have a problem on his hands. Truly, he'd thought this the day his parents had informed him of a brother, to be born in a few months' time. Mycroft had loathed the idea, but of course had no power to stop William Sherlock Scott Holmes from coming along anyhow.
On the 13th of May, 1995, Mycroft began to wonder what exactly his brother got up to when he was out of the house on those late nights. Coming from such intelligent stock, neither Mr. nor Mrs. Holmes worried about their sons, not as much as other parents are wont to do, but in this case, they should have worried.
Mycroft possessed incredible self-control. He always had. His younger brother, however, lacked severely in this area. He compensated for it in genius, in his own way, but rarely showed any sort of filter on his comments or facial reactions. An unspoken agreement between Mycroft and his parents suggested that there was perhaps something more than a little different about Sherlock, and Mycroft took it upon himself to keep an eye out.
But May 13th was the first time that the 19-year-old came across a new emotion: fear. That was the night upon which Mycroft had stayed up reading in his wait for his brother. He did this whenever Sherlock disappeared into the night without a word, and he did so without fuss. His duty was to watch out for Sherlock. That was all.
Four days prior to this night, however, Mycroft had done the same thing—waited in his bedroom, reading atop the covers in silence. When the front door opened and shut, none too quietly, and Sherlock walked past his brother's room for his own, Mycroft got up and went to lock the door. Sherlock never bothered to. Before he had taken the first step into the hallway, he could smell the marijuana. Mingled with this was the distinct smell of a Lucky Strike brand cigarette.
Mycroft knew he shouldn't be too worried. Sometimes young boys did stupid things.
But Sherlock wasn't any ordinary boy.
Perhaps he had taken up the habit from seeing Mycroft smoke the occasional pipe with their father. Nothing to be concerned about. And those Lucky Strikes were said to sometimes have marijuana put in on accident; Sherlock may not have even known what he was buying.
But Sherlock was smart enough to know.
Mycroft shrugged off his bothersome thoughts and proceeded to lock the door.
Those few days later, he wanted to kick himself. If he had only listened to his instincts, Sherlock wouldn't have come stumbling into the house past midnight, his eyes on the hint of bloodshot and clothes filthy. If he had given his genius intuition credit, he could have prevented Sherlock's freefall.
From there, Mycroft would proceed to find Sherlock not at home, but out in the streets, or holed up and writhing on a soiled mattress on the floor of an abandoned building made sanctuary by street rats and users. As they got older, Sherlock liked to say that Mycroft having to carry him to the car was an isolated incident, or to blame away these events as the key to solving a singularly difficult case in which he had to go deeper than usual.
Mycroft knew he had to care for his brother. He knew if he didn't that one day his parents would receive that fatal call. He couldn't let that happen.
So the years passed. All he asked of Sherlock was that in these episodes he wrote an alphabetized list of the drugs he chose to intake, and Sherlock always did so. Though he refused to refer to himself as an addict, he didn't have to: he knew that his older brother would be there, always.
Even if it killed them both.