1
There were thirty seconds before the bomb went off. Holmes stepped into the upstairs room softly. Watson looked up at him, blood soaking through the front of his shirt. Holmes smiled and joined him on the floor, lifting him to sit up and embracing him with one hand around his back and the other holding the back of his head. He put his cheek next to Watson's and felt the doctor weakly grip him in return. There were two seconds before the bomb went off. Holmes faced the doorway and thought of a melody. Watson faced the window and thought of the sun. There was one second.
2
The bomb failed to explode. Holmes could feel the warmth of Watson's blood on his own skin, the damp of it as it soaked his clothes, the dead weight that told him Watson had fallen insensible in his arms. Was he dead? Holmes didn't have time to determine it. He stood very carefully, lifting his friend onto his shoulder and glancing over to the bomb, then the window. No, that was too far to jump, Holmes had known that already. Down the stairs, then, and as gently as he could.
3
The explosion knocked him off his feet. Both he and the doctor he was carrying hit the ground hard. His ears rang, the world slowed, and the only thought in his head was that he needed to cover Watson. He crawled over top of his friend's body, shielding it from debris falling around them and hoping to God he was still alive.
4
Watson was taken away from him as soon as those around them had recovered from the blast. There was blood all over Holmes' clothes and he knew vaguely that people were staring at him. He felt the sharp sting of being slapped, but only half-listened to Lestrade scream at him about what a damn fool thing it had been to reenter a building about to explode.
5
Holmes had known he'd go back in after Watson. He also knew Watson would have done the same if it was him bleeding next to a bomb. That was just how they were; they may agree to stick to the plan, but each knew full well that if they both weren't outside at the rendezvous then one of them would be going back in and they would be saving the other or dying in the attempt. That was just the way it was, and, despite all his yelling, Holmes was certain Lestrade knew it, too.
6
Watson lived. He was confined to his bed for over a fortnight which nearly drove him mad, but he lived. Holmes stayed nearby, not leaving London for his cases and not staying anywhere but Baker Street for more than a single night at a time. Watson was more grateful than he could say for his friend's kind attention, and so he didn't. He didn't need to, just like Holmes wouldn't have needed to if their positions were reversed.
7
Holmes never asked if Watson remembered their final few moments before the bomb was supposed to explode, but if he had then Watson would have said no. He didn't remember how calmly Holmes had come for him or how gently he had held him when he thought they were both about to die. What Watson did know was that it didn't matter. He didn't know any specifics, but he knew Holmes would have been with him at the end and would have been the one who carried him out. He couldn't imagine it happening any other way.