"Hey, freak!"
That sound is a familiar one and John doesn't even flinch. He is disgusted with himself for becoming so desensitized to the word, though Sherlock doesn't seem to mind. He brushes by Donovan with an impressive disinterest, eyes focused on the acid-eaten corpse they've come to see. Even so, John curls his hands into fists as he walks by.
That particular word is used for over a year (for John that is; far longer for Sherlock) until one day they pin a man spitting and screaming to the pavement. He's enough of a psycho to have eaten three infants and yet he lifts his head, looks upon the man who caught him, and pronounces him "freak." John is too busy helping Lestrade to notice Donovan.
"Hey, asshole," she says a week later. Sherlock doesn't care, but John immediately halts; stares. Donovan looks away.
"Asshole" lasts all of a month. Then Sherlock saves her life in a shootout, covering her body entirely with his own. Donovan refuses to call him anything for weeks afterwards, until she eventually settles on "loser."
Then Sherlock jumps.
Two years later she's staring at John with relief and guilt and stubbornness that she'd just done her job. She bitches about his "boyfriend."
John is tempted to correct her—but stops.
He can deal with "boyfriend."