Sherlock was quiet for a moment as they walked, following the lights.

When he finally spoke up again, he said, "The reason I'm doing it, John, is because as of right now, you don't believe this is real, or that we're both alive--at least not entirely. You're a soldier, you're usually somewhat cautious unless someone is directly in danger--you wouldn't have walked into those vines the way you did under normal circumstances. That means you're still not entirely convinced."

He wasn't sure how to articulate the next part, but tried to soldier on through it.

"A moment is going to come when you realize you're not dreaming this and that neither of us are dead, and that's the moment you're going to be utterly furious with me."

And probably punch him in the face.

"And quite frankly, I am absolutely terrified our friendship isn't going to survive it. I'm hoping that if you have this to look back on and understand that I'm trying to be sincere that it will help mitigate your anger with me."

He was hoping that John would understand he really was sorry. That this time he wasn't faking and trying to slip something in John's drinks.