Response to a delicious little prompt on the Sherlock kink_meme.

Prologue

What they both know is: the world is anonymous. It's full of people and things and seething trackless oceans of irrelevant data. Lives are nothing but noise in that cacophany. It's others knowing you that lifts you out of the background static and makes you real, and practically no one sees anything. Two people who take the trouble to notice one another in a crowd are as good as alone in the throng.

And that's fine, really. It's better than fine, because being real involves so many obligations, and obligations are exhausting and confining and sap you of all the things you are deep down where you don't want anyone to see. And where, to be fair, mostly no one else wants to either.

They see each other. That's reality enough. They are both alone in the world, but they're alone together.