At the crime scene, things had started out rough. Anderson was being particularly sneering today, and Donovan had started to make snarky comments to John about his hobbies and bad taste in friends and flatmates. Lestrade was tired, and a bit clueless about the various types of scimitars, and, like John, was failing to make the same creative leap as Sherlock from scimitars to azaleas. The final straw was when Inspector Dimmock showed up and started an argument with Lestrade about who's precinct the murder was in (apparently the girl had been found in Lestrades and the elderly gentleman was found in Dimmok's) and the squabbling and shouting had gotten so loud and out of shape that Sherlock (who was actually trying to prevent more lives from being lost instead of calculating overtime costs) threw a minor temper tantrum that involved punching a conveniently located mirror.
John wondered why he hadn't seen the rubbing before now, but he assumed that it was merely something that people who thought they knew Sherlock would never think to look for. He had the hem of his shirt out from his pants right now and pinched tightly between his thumb and forefinger as he hurled abuse at both the D.I.s in such a manner as would put Mr. Holmes in the category of petulant young godhood; perhaps some enraged Adonis. For his part, John was shrinking back into a corner away from Anderson and Donovan and out of the range of sight of Lestrade and Dimmock. He had begun to notice that occasionally the D.I.s turned to him in an attempt to manage Sherlock, which he was moderately successful at, but honestly, the childishness of the spate and the potential lives at stake had tossed John completely on the side of his flat mate. He stared at the dead body on the ground, which was rather messy from the scimitar, and as was the case of most dead bodies, had very little opinion on the subject.
Occasionally, John had seen Sherlock, in a pique of frustration (usually during a drugs bust), grab his skull off the mantle and twist it around in his hands, stroking the counters of the object with his fingers and tapping the different bones as he murmured something close to a chant under his breath. Once, John sidled up close enough to hear:
Frontal, Parietal, Occipital, Temporal, Sphenoid, Zygomatic, Nasal, Maxilla, Mandible.
At the time, it hadn't made much sense why a consulting detective would need to chant the different bones on the skull, but now that John had mentally established the skull was some kind of security object to Sherlock, it made quite a bit more sense. The rhythm, and the repetition must quite comforting and grounding to that huge bloody brain of his.
Now, Sherlock stalked around the room in high dungeon, glowering at Lestrade who was trying to calm everyone down and at Anderson and Donovan who seemed to have set up an impromptu betting pool as to whether Dimmok or Sherlock would win this little tiff. Dimmock himself, though considerably shorter than Sherlock, looked as though he was seriously considering rolling up his shirt sleeves and going for it. Occasionally, Sherlock's graceful demeanor, poncey clothes and high cheekbones gave people the impression that he was an easy hit, while he was actually quite good at boxing.
Sherlock's stance changed minutely and his eyes narrowed, as Dimmock clenched his fists at the side of his legs. John knew that if he threw a punch, Dimmock would have about 20 seconds before he was flat on his back from a consulting right hook to his jaw.
"Sherlock." John said gently as he appeared by his side, "You're bleeding." He gestured for the hand that punched the mirror, but Sherlock, seeing an object (well, human being. Well, skull replacement) that conveniently offered itself to him for analysis, grabbed John's head between his hands and firmly but gently tapped each bone:
Frontal, Parietal, Occipital, Temporal, Sphenoid, Zygomatic, Nasal, Maxilla, Mandible.
John drew his brows together in awkward concern, but after two rounds of gentle tapping, beginning at the front of John's head and making its way down the back of his head, to his cheeks and ending at his jaw, Sherlock placed a hand on his shoulder and looked at him calmly. "Nice. More portable."
Thankfully the cut on Sherlock's hand was nothing serious, but John could already hear sniggers of "Sherlockian Mind Meld" from Anderson, and was fairly sure Lestrade and Dimmock would not have looked more surprised if he and Sherlock had just got done giving each other a passionate snog.