Written because Anderson gets such a bad rap in fanfic, and too often I've seen him and Donovan portrayed as these cartoon caricatures of schoolyard bullies. In truth, I feel sorry for them both.
Character Study: Anderson
Him again. At Anderson's crime scene, rooting through Anderson's evidence, interfering with Anderson's job.
Every time there was something interesting, the amateur showed up with a snide remark, a sidelong jibe at Anderson's competence, and proceeded to explain in excruciating detail why everyone in the Yard was an "idiot". His lip curled in something closer to a snarl than a sneer as Holmes listed in verbal bullet-point the oblivious incompetence of Lestrade, Anderson, Donovan, the entire team.
That fucking psychopath.
"Idiot!"
Something in the way Holmes spit out the word set Anderson's teeth to clenching. He had his degree, he had experience, he wasn't on this team for incompetence, he certainly wasn't an idiot - no, no, his performance in university put the lie to that, whatever his marks in secondary school may have suggested -
"Christ, boy, look at these marks. I swear you're some stupid bastard's son and none of mine, not with your sister being so clever and me like I am. Or maybe you get the lack of brains from your ma, yeah?"
His hand clenched too, a shaking fist at his side and he found himself glaring daggers at the amateur that Lestrade insisted on letting into Anderson's cases.
He'd proven his da wrong. Over and over. Studied so hard at uni that he'd made himself sick from stress and lack of sleep. Top of his class in the end. Forensics. The Yard. Up and up until he was here, clawed his way onto this team with diligence and work and attention to detail. A stupid, incompetent, oblivious person wouldn't have been hired, much less be able to make it to Anderson's position.
He was not stupid.
He was not.
Something about his posture, or his expression, or maybe the seething fury that radiated from him - something about it earned him a sidelong glance from Holmes. And - was it his imagination, or did the amateur smile? Quick and dryly amused and gone before he could blink, but he could have sworn...
Holmes knew.
Of course he did, he was some sort of psychopathic savant (Anderson refused to credit Holmes with something so honest as study and hard work), it was uncanny how he managed to draw accurate conclusions from minuscule, seemingly irrelevant details. Of course he knew, he knew somehow about Anderson's brilliant (addicted, manic, uncontrolled) sister, he knew about the mantra of stupid, idiot, lazy, useless, bastard that his father drilled into his childhood and adolescence with belt-leather punctuation.
Outrage at Holmes' interference in his job, anger, old bitter pain, wounded pride - the entire cocktail of roiling emotions settled down into Anderson's gut and brewed there into something black and tar-sticky, something entirely like hate.