Disclaimer: I do not own Sherlock Holmes, in any incarnation.

Note: This is not a ship I expected to end up writing for, but once I'd thought of it, it was too cute to ignore. Thank you to prettybirdy979 for the encouragement - I finally decided to upload this little ficlet, although I never did get round to expanding it...

Sherlock is not sure whether to be amused or insulted by John's laughably frail attempts to conceal the identity of his latest girlfriend. Really, how the pair of them can have thought to keep it from him for more than a few hours – and then only if he were distracted by a particularly interesting case at the time – is anyone's guess.

By Sherlock's calculation, this is their fourth date (fifth, if you count the one cut short ten minutes in by Sherlock demanding John's presence at a stake-out), and while his interest in John's sordid love-life is minimal at best he would have expected some sort of announcement by now. Isn't it one of those normal-people-things, that when two of one's friends enter a romantic relationship they are expected to make themselves known? Their reticence intrigues him.

He is debating when would be most advantageous to mention the anomaly to John when his flatmate enters the room, adjusting the collar of his new shirt and scooping the bouquet of flowers (an apology for the last interrupted date – unnecessary, Molly is always more intrigued than annoyed, but perhaps a force of habit) from the arm of the sofa.

'I'm –' John begins, in that slightly strained voice that means he is being very careful about his choice of words.

'Do ask if the toxicology results have come through yet, won't you?' Sherlock interrupts, raising his chin from where it rests on his fingertips and fixing John with an all-too-knowing gaze. John's expression flickers most comically from momentary panic to feigned confusion.

'Ask who?' he replies after pausing too long, tongue darting out to moisten his lower lip in a characteristic and remarkably obvious show of nervousness. Sherlock merely raises his eyebrows; John manages to maintain his façade for almost a full three seconds before his shoulders slump in resignation and a look of reluctant acceptance crosses his features. He sighs. 'How long have you known?'

Sherlock notes, to John's credit, that he doesn't ask how he knows. He is learning. Again, Sherlock simply raises his eyebrows.

'Why didn't you say anything?' John exclaims suddenly, throwing up his hands in frustration. A petal detaches itself from one of the flowers and settles in his hair; Sherlock smirks as John brushes it away irritably.

'Such as what?' Sherlock queries.

'I don't know, you usually come up with something disapproving enough about wasting time or energy or –'

'Maybe I don't disapprove,' Sherlock interrupts without thinking. He is almost surprised to find that it is true.

'I – you … what?' John splutters eventually.

'You heard me,' says Sherlock.

'I'm not sure I did,' John clarifies honestly, 'because it sounded like you just said you were happy for us.'

Sherlock looks scandalised.

'It sounded like nothing of the sort. It's an efficient solution, that's all.'

'An efficient solution to what exactly?'

'Oh please, you know as well as I do that the reason your other relationships have all failed is because they were all too petty and jealous to put up with the knowledge that they were not the most important part of your life –'

'Because of course that's you,' John cuts in sarcastically, rolling his eyes in exasperation.

'Of course,' Sherlock agrees easily. 'None of them could handle your lifestyle because they were all too fixated on being dull and domestic –'

'Careful, you're skating dangerously close to calling Molly and I interesting.' Sherlock can hear the smile in John's voice, even though he does an impressive job of keeping it from his lips. He continues as though John hasn't spoken, though.

'So you spent half your time distracted by making unnecessary apologies because you're too frustratingly polite to admit that they bored you – don't deny it – and as I have tried to tell you before, allowing your brain to be filled with things which are unnecessary can hardly fail to have a detrimental effect on your already limited intellectual capacities. Thus, if you are going to insist on continuing your romantic efforts it needs to be with someone who accepts the other aspects of your life –'

'Meaning you.'

'Enter Molly Hooper, who already knows about our work, and, rightly of course, admires rather than resents it –' (John notices, not without a little bubble of warmth in his chest, the our) '– furthermore, as you are far too moral to take advantage of her otherwise, she must be getting over her infatuation with me, which, while useful, does have the unfortunate effect of rendering her unable to operate at her full potential in my presence.'

'I'll tell her you said that, she'll be flattered,' says John, and he means it; it is the closest Sherlock is ever likely to come to admitting he finds Molly's abilities, more than just her place of work, genuinely useful.

'Conclusion: If the pair of you engage in a romantic relationship you are both much more likely to be of use to me in cases. Therefore, an efficient solution to everyone's problems.'

'That's a very long-winded way to say you're okay with it.' John pauses, 'thanks.'

'For what?' Sherlock scoops his violin from the floor beside his chair and raises it to his shoulder, but doesn't begin to play just yet.

'Never mind,' John shakes his head. 'Toxicology reports, yeah?'

Sherlock nods, closing his eyes and bringing the bow up to rest on the violin strings. He deliberately does not let the smile rise to his lips until he hears John closing the front door on the way out.