Up on the roof, with Moriarty’s body cooling behind him, Sherlock was convinced he could brazen though Lazarus and jump without a second thought.
“Oh God.”
But John arrived, and he found holding to his plan harder than he realised. Listening to his blogger plead more and more desperately to stop, come down, not do this, Sherlock felt a sharpness in his throat that had nothing to do with the cold rooftop wind.
The script was exact, the call was being recorded. But the tears that threatened to spill down his cheeks… they were unplanned. His chest constricted, his hands tightened on the phone. Searching for something (anything) that could signal to John that it would all be alright, adrenaline coursing even over the pounding of his blood, Sherlock tried.
God, he tried.
“It’s a trick. Just a magic trick.”
“No. Alright? Stop it now.”
The ground was getting farther and farther away. John Watson was a brilliant, shattering beacon. 
“Goodbye John.” On the tarmac, with the buzz and drone of airfield business all around, he faced John again - another last moment - pressing his lips together firmly. The was banter, awkward in the face of a parting they could not undo. A change they could not survive. 
“How long?”
“Who knows.”
And tears again rimmed his eyes as he searched for the right words. The real words.
“John, there’s something I should say. I meant to say always and then never have… since it’s unlikely we’ll ever meet again, I might as well say it now.”
No more goodbyes. No more begging. No more false lines to push between them. 
But John looked away, and he knew (he was Sherlock Holmes, after all) by the hunch of shoulders and small, firm line of mouth that John Watson was steeling himself for a truth they both knew, but would be forced to live without the rest of their lives. 
Throat tight, eyes swimming, Sherlock searched again for the lifeline - the hint that somehow it would all be alright. They would find a way to go on, even if it must be without each other.
“Sherlock is actually a girl’s name.” The laughter that followed chased his tears back. When their hands folded together it was again the very best of times. On the plane, alone, he allowed himself to cry.