Part 1: Flashback #1

I was once a friend, a Holmes friend.
A friend to Eurus.
A friend to Sherlock.
A friend to Mycroft.
Now I'm that shadow that follows their every step and pushes them in the right direction.
But I'm also forgotten by my best friend, locked away in the mind of the girl I had pushed and helped to strive, and thought to be dead to the man I consider a brother.
But maybe it's time for shadows to come to light.
Warning: may contain violence, cancer, suicide, death, and brief mentions of drugs.