"Then what? The probability that the first time out we get squashed?" John's pushing buttons even though he doesn't know a lick about Sherlock and it should probably stay that way. Once people get close -- not that they ever get close -- it all goes downhill from there. He can tell in one look if you've had sex, he knows what you had for breakfast by the way you fold your napkin--

John doesn't buy it. No one's like that. Sherlock's just...cold. Cut off. Distant. And that's probably what makes him ideal because there's only going to be John's baggage in that shared space between them. In each other's heads.

"I don't care what you might think you have to hide, Sherlock. Drifting unnerves people because co-pilots know everything. But I'm open. And it's all fine."