A slightly-deflated Sherlock re-entered John's building. The adrenaline rush that had accompanied him across the road was gone and, in its place, the comedown that inevitably followed.
As he started to climb the dark stairwell, however, he remembered: John.
Oh dear god, John. His John.
A switch flicked in his brain and, taking the remaining stairs three at a time, he flew higher and higher; closer to John.
Despite his impatience, as he approached the entrance to John's flat, an uneasy feeling of uncertainty and panic grew in him.
What if John couldn't forgive him? What if he hated him? Rejected him? He paused a moment; considering whether returning to John was, in fact, the right thing to do.
Did Sherlock's return to London, even now, put John at risk? With the threat of this " S. Moran" - Sebastian? It couldn't be, could it? - Sherlock couldn't help believing that there was a still clear and present danger surrounding him, and that every minute he spent there put John in harm's way.
For a while, Sherlock stood outside the door; his head pounding and his heart racing. He needed to fix this.
He was prepared to do anything, but did that include, once more, leaving John behind?