"Hullo, Freak. Hullo, Freak's assistant." Sally's barbs lack her usual enthusiasm, as if she's just mocking them out of habit. Her eyes look red and puffy, and her usually lustrous hair is unkempt. John pauses, debating asking her if something is the matter, but notices the tension in her back and thinks better of it.
When they get to the centre of the crime scene, it's buzzing with activity. Anderson turns and sneers, but the wrath and ire generally reserved for Sherlock seems to be aimed in another direction. Sally Donovan turns on one heel and storms back out to the front door, after escorting them in. The tension between them is palpable, and strangely, John finds himself feeling sympathetic towards the two of them.
Sherlock, however, has chosen to ignore the anxiety in the room. If John noticed it, surely he did too, but he's not taking pity on Anderson, and the two of them have begun bickering in earnest. Anderson looks almost relieved to have something more familiar and less difficult to be obnoxious about, so John doesn't step in to try to prevent the argument.
Finally, Sherlock is done. Smiling awkwardly, John nods at Sally as he steps under the tape, dragging Sherlock with him. Best to let the two of them deal with another particularly messy break-up.
I wanted to use this word but couldn't bring myself to do anything angsty involving John and Sherlock. Poor Sally and Anderson. They so often get the short end of the stick in this fandom.