Note: A rehashed version of a scene from A Scandal in Belgravia.
"She's, er, in America."
Hear the man speak, thought Sherlock. Hear how a man who is unaccustomed to lying is trying his best to lie. Not for any of the selfish reasons which forms the basis of usual, mundane everyday lies, but for his friend; for his friend who does not feel things the way people feel things. John Watson, who knows the way Sherlock is, and knows full well first hand how Sherlock does not "spare people's feelings", is lying in the most obvious and awkward way to do just that. To spare him pain.
"America?"
"Mmm-hmm. Got herself on a witness protection scheme, apparently. Don't know how she, swung it, but, er, well, you know. "
This should amuse him, but rather, in intrigues him. Just how far will he go? For Sherlock, that is. He keeps his eyes on the microscope but cannot help darting quick glances towards his friend who is standing in the doorway of their kitchen, all tension and pain. Pain on Sherlock's behalf. Carrying grief and shock which is by rights Sherlock's. He can see its weight on John's shoulders and is once again filled with wonder. Why does he bear it? By choice, too, at that. No one can force him to do anything. John Watson is an upright, strong, and honourable man. Yet every time, in each and every instance, he chooses Sherlock above himself and makes him his top priority, above and beyond his values and standards.
"I know what?"
"Well, you won't be able to see her again."
And his own feelings. Sacrificing his heart.
Sherlock is aware that Irene Adler had upset John, in more ways than one. This delighted Sherlock, and unlike himself, he is ashamed of the sharp pleasure he felt at this. Yet it was simply marvellous and wonderful to learn that John wanted their relationship to be the special relationship for both of them, as much as he did: It was not just Sherlock, who didn't do people and relationships, who craved this relationship.
And John would bear it all without a single word of complaint. From normal, everyday rudeness that Sherlock throws in his face, to lying for him, killing for him, and bearing his pain. For John is not a man fluent in the art of deception. Still he will make an attempt. For Sherlock.
"Why would I want to see her again?"
"Didn't say you did."
Such consideration. On Sherlock's behalf. Tact and understatement. Both of them Sherlock's weak areas. The conversation continues. John even undermines the British government (Mycroft) and lets Sherlock have the phone. Sherlock wonders briefly if John would actually go against a whole country if Sherlock needed him to. Perhaps. It seems there are no boundaries, no limits.
So he confirms, once again, what he already knows:
John Watson is beyond the art of deduction. This was what Sherlock had found during the time they spent together. He simply is, and Sherlock just needs to understand him, as he is. That is all. And for some strange reason, this simplicity didn't bore him. At all.