A/N: Reviews are appreciated, guys! Also, if you have any suggestions as to scenes I should write up, let me know.
"How could you say that to her?"
Peter was practically yelling at Sherlock - something he had promised Olivia he wouldn't do - but he didn't care at the moment. John looked up disapprovingly from his reading position in the armchair, but Peter ignored him as he stormed into the flat, where Sherlock was calmly playing his violin at the window. At Peter's interruption, the consulting detective only glanced up.
"Agent Dunham is hardly vulnerable to criticism," the Englishman replied, seemingly still engrossed in composing music. As he began to turn away, Peter crossed the room in a few strides until he was standing directly in front of Sherlock.
"Then you've got the wrong definition of 'criticism'," Peter snapped, "because telling my partner that she failed her job on all accounts? That sounds a lot like an insult to me."
"You said that?" John asked, now looking at Sherlock with a mix of surprise and disapproval.
Sherlock just shrugged, still playing.
"I told her the truth."
"You told her condescending bullshit."
Sherlock drew a few notes on the music sheet in front of him, then returned to playing.
"Agent Dunham's emotional investment in this case-"
"-is how she treats every case," Peter finished curtly. "This is how she solves her cases."
"Then she's an idiot," Sherlock said matter-of-factly.
Peter made a motion as if to throw himself at the Brit, but John stood up abruptly, getting his attention.
"Look. We've just got differences in method, all right?" The doctor looked between the two of them: Peter standing tensely with hands in fists, and Sherlock blithely playing away on his violin without looking at either of them. "Each of our track records show that our different methods work. So let's just try to get along. Then we can go back to our own countries and cases."
After a long, taut moment in which Peter looked like he was debating whether or not to punch Sherlock, he finally stepped away. Unclenching his hands, he looked at John.
"Fine. But if Sherlock says one more thing against Olivia-"
"He won't," John assured him. They both knew he was probably lying. After one more glare at Sherlock, Peter strode towards the door. Sherlock, still facing the window and playing the violin, didn't look around as he commented, "Mr. Bishop, don't forget to control your own emotions."
Peter paused, then looked back at him.
"You're a real son of a bitch, Sherlock." Without another word, he left the room.