"Freak."
Maybe it's just the tone in which she says it. Maybe it had always bothered John, and this was the absolute breaking point. Maybe it has a little something to do with the fact that this was only the third case since a particular Sunday had occurred that had consisted of a look, a fainting spell, a punch, and then a tearful hug. It doesn't matter. This is the last straw.
For God's sake, Sherlock and he had just walked in. That was literally all they'd done. Then the damn woman looked up at them, curled her lip, and sneered that hated word, and then returned to inspecting the body with Anderson like she'd done nothing wrong.
"I'm sorry, what did you say?" John asks, almost sounding polite when he is oh so not. Donovan looks up in surprise, evidently not expecting to have been answered. "What did you just say?" John repeats, more slowly and obviously, like he's speaking to a child, which he might as well be.
Anderson and Donovan, hunched over the body (an unfortunate soul who had somehow been murdered by a rubber chicken lodged wholly in his throat; this unintentionally hilarious detail was what had drawn Sherlock to want involvement in this case in the first place) exchange confused glances. Lestrade pauses while talking to another officer and looks over. Even Sherlock gives John a look out of the corner of his eyes. John is tempted to tell them all, sans Sherlock, to go stick their pistols in a choice unmentionable area.
"I said 'freak,'" Donovan answers, staring at John, as though testing her boundaries, which she had finished straddling long ago and was now doing the chicken dance on the wrong end. "Problem?"
"Problem? Oh, right, problem, no. Why would anyone have a problem with that?" John rolls his eyes heavenward dramatically. "You didn't just call Sherlock a freak. Oh. But you did. But there's nothing wrong with that, no."
"John," Sherlock says. John ignores him.
"Look, he's just got back a week ago after months of m- us thinking he was dead, and that's really all you have to say? 'Freak'"?
Donovan is visibly uncomfortable now, evidently having never been called out about her blatant disrespect, and John is relishing the feeling. "You know, besides the fact that he's my best friend-" John puts a protective hand on said best friend's shoulder "-and I should've set you straight the first time you started this, he also solves pretty much all of the cases you cannot handle, and this is how you thank him? Really?"
"Control your boyfriend," Anderson mutters under his breath.
"And you," John starts again, now rounding on the man as he faintly hears Lestrade muttering Oh God somewhere behind him, "you are just as bad. I thought Sherlock was exaggerating when he said you lower the IQ of the street when you talk but, boy was I wrong. I can just feel my brain withering when I talk to you."
Sherlock's biting his lip. John hopes that's not a bad thing, but can't find it in himself to care too much. "And while we're on the subject, for the last bloody time, I am not bloody gay."
"John, it's a crime scene," Lestrade says. "Do try to save it."
"It's about to be a worse crime scene if some people don't cut it out."
"Oh, but that would be boring," Sherlock says. "We'd all know who did it."
"Shut up, Sherlock."
"Just saying."
"Shut up, Sherlock."
Sherlock falls silent, and is silent throughout the rest of the night save for detailing numerous observations to Lestrade, and the case is closed rather quickly when Sherlock is able to infer that the victim's chicken-hating mother-in-law is the culprit.
After that, not a single word is spoken as John and Sherlock walk home. But no words are needed when Sherlock steers John into their favorite (and most expensive) Chinese restaurant.