Their first kiss was under the doorway.
John had opened the door to find an extremely sorry looking Sherlock.
His first instinct was to punch him. As soon as John's fist had connected with Sherlock's face, not even bothering to miss his nose or eye, John was in Sherlock's arms, John's mouth pressing hard against his.
Sherlock didn't even try to pull away. He hadn't foreseen this outcome, not even the slightess hint of forgiveness had Sherlock calculated in any situation.
They remained in each others' embrace, John's face pressed into Sherlock's chest, his shirt becoming damp with John's tears.
"Don't ever leave me again" mumbled John into Sherlock's shirt.
Sherlock kissed the top of John's head.
"Never."