John can't decide if he wants to punch Sherlock right away. On the one hand, the fact that the posh berk has managed to come out of that brawl not only unscathed, but looking as if he'd stepped out of a Jermyn Street catalogue, is ridiculously irritating; but if John gave into the impulse to punch Sherlock every time he noticed that the man was obnoxiously good-looking, his entire pension would be going to ASBO fines. On the other hand, John suspects that if he doesn't himself lodge some very concrete arguments on the subject, Sherlock is never going to stop flinging them directly into harm's way. He starts the fights, and John finishes them.
Wiping away the trickle of blood from his cheek, John stalks up to Sherlock, who casts a breezy glance in his direction and raises an eyebrow. Of course he does. Sherlock is arguing with – or rather, being argued at by – a very angry police inspector.
Sherlock sighs dramatically, which apparently pushes the inspector over the edge. A moment later Sherlock is reeling back, hand to cheek, and Dimmock runs up to lead the perpetrator away.
"John," Sherlock breathes, clearly aghast that his friend did not intervene. John merely takes Sherlock's chin in his hand and inspects his face.
"Yep," he says, with grim satisfaction. "That'll bruise."