He had, of course, known for months that the Potter boy would be coming to Hogwarts this year. And, of course, that it would be his misfortune to have to teach the brat. What would he be like, this so-called hero (his lip curled automatically) who in mere squalling infancy had managed to defeat the greatest Dark wizard of the age?
No doubt, as befitting a Potter and a celebrity, the boy had been raised in comfort, indulged by his guardians, trained to that same nauseating self-assurance that James (even now, the mere thought of the name was a curse) had always possessed. Not even Lily's humbler blood could hope to dilute that Potter arrogance.
Sorted into Gryffindor -- of course. Eyes narrowed, he watched the boy slide off the stool to the sound of his housemates' cheering (it had begun already, then) and hurry, light and sure on his feet, to join the others at the Gryffindor table. Until this moment he had not got a good look at Potter: when he entered the Great Hall he had been indistinguishable among his fellow first-years, and then had stood facing away from the High Table until he was Sorted. Now, however, he could see the boy clearly, and the cruelty of the resemblance took Snape's breath away.
James's stamp on every bone of his face; James in the cold glitter of glass that masked, like some fresh insult, Lily's beautiful eyes; and worst of all, that damnable hair of James's, deliberately tousled for effect. Eleven years old, most likely hadn't even seen a broom yet, and the brat was already preening himself to look like he'd just won a hard Quidditch match.
Harry Potter was, clearly, even more like his father than Snape's most cynical imaginings had anticipated. And as he looked at the boy, already surrounded by a throng of chattering admirers, he felt the already fragile shell of civility crack within him, unleashing a hissing serpent of bitterness and hatred and rage.