Prompt: "hatred."
Hermione hates him. When he sneers at her in class, yellowed teeth showing in an unbecoming snarl, as he calls her a know-it-all, a bookworm, acidly inquires if she's managed to regurgitate her textbook in her last assignment as well. When he stands just behind her, looming over her shoulder as she does her best to make the day's potion. She knows it's perfect, it always is, but he docks points anyway, the smirk playing on his lips as she realises she can't speak up or she'll attract a detention.
She hates him when he sweeps past her like an overgrown bat in the hallway and makes insulting remarks under his breath about her bushy masses of hair. As if he's one to talk! she thinks and sticks her tongue out at his back. He watches her at meals and she finds herself becoming flustered and self-conscious, stuffing half a roll in her mouth and trying desperately to talk through it. Harry and Ron don't notice, but she can feel his laughter, and she despises it.
She doesn't know when the hatred begins to change. When she begins to appreciate his closeness at her elbow while she stirs counter-clockwise, her breath barely stirring the glimmering surface of the potion. When just for a second, there is approval in those glittering black eyes when she answers a question. There are more notes written on her essays than she's previously noticed, and for once, they're intended to help, not mock.
When his eyes light on her in the middle of the crowded Entry Hall, or slipping into dinner, her breath catches in her throat and her cheeks blaze red for reasons she can't grasp hold of. She finds herself longing for the day she can walk free of Hogwarts' doors, when she can call herself a student no longer. She smiles at him in NEWT-level Potions and has the satisfaction of hearing his breath hitch, of watching the narrow shoulders draw tight for a moment. The scars from Nagini's bite draw thick, puckered lines across his neck and shoulder, but she finds them beautiful.
When she graduates, she comes right back that evening, and knocks on his door, her heart beating so loud she can hear it echoing in her ears. Her entire body trembles, and she wonders if she's made an error.
Then the door opens, and Severus is right there, gazing at her, and she knows she hasn't.