A/N: This was my entry to Naruto100's 'Betrayal' challenge.
Genocide
Itachi had known ever since his little brother had been born that the boy would inevitably be doomed to follow in his older brother's shadow. After all, Itachi was a genius, he had been born one. And no family had more than one prodigy after all. Not even the noble Uchiha clan. And Itachi was the family prodigy. Not Sasuke.
But even though Sasuke wasn't a prodigy, he was still talented. Anyone without talent didn't fare well with the Uchihas. Itachi didn't have compassion, he was an ANBU leader, but he did have… something. Something that made him seethe with hatred watching his father belittle Sasuke. Sasuke wasn't Itachi. He would never be Itachi. He was Sasuke. Fugaku didn't seem to see that.
Shisui knew, before he died at least. Mikoto knew. But the military police didn't know. What did they know about Shisui? About Sasuke? About Itachi? They knew nothing, not them, and certainly not Fugaku. That's why Itachi thought it was funny, what Fugaku said when he found his elder son.
"You have betrayed our clan, Itachi." He had said, after his wife had been slain. Itachi had glanced down at Mikoto, the woman who had birthed him, and felt not one trace of remorse. He had been a little surprised that she had attacked first, but other than that, he felt no compassion. It was with a smile that he turned to his sire, idly cleaning his dam's blood off his blade.
"No, father. I haven't betrayed you." Itachi gave a low, grim chuckle. "You betrayed us."