“I think there was a friendship instantly between Martin and Benedict. They’re not at all like the parts they play. But the relationship between them really informs the much pricklier onscreen relationship. Because obviously Sherlock’s a quite cruel man at times and John is quite a put-upon man at times. But you won’t buy that, you won’t enjoy that unless you absolutely feel that in every scene, in every heartbeat that there is that proper, underlying warmth. That real, proper, solid friendship. And that friendship has actually happened between Benedict and Martin. And the value of that you get onscreen.” - Steven Moffat