"Can anyone tell me why one shouldn't use the Unforgivables?" Snape's eyes raked the class, settling on Susan Bones, who had her hand in the air.
"They're illegal, sir."
"Ah. The proper, ministerial, response." Snape sneered, "There are a thousand curses and hexes that are illegal, most of which you can find detailed in the Hogwarts library - even the darkest, should you manage a pass into the Restricted Section. It's ritual magic that the Ministry has most persecuted."
Snape drew a breath and continued, "Why are these three curses ones you should not rely on?"
Rely. It was a word that Harry Potter knew well, and he instantly knew what Snape was talking about. It wasn't the illegality, but the difficulty of the spell. I wonder if anyone else figured it out?
Hermione raised her hand, and Harry tuned her out, already knowing that she'd be saying these are the three that will send you to Azkaban, no questions asked.
The question went around the room, Neville and Seamus and Dean trying to answer it, along with Anthony.
Finally, it was Greg Goyle who raised his lumberous arm.
"Yes?" Snape asked brusquely, which was still a sight above the consideration afforded to Gryffindors.
"The Unforgivables... well, they're hard to cast, sir." Goyle said.
And, because it was Greg Goyle, whom most people didn't know had any feel for magic at all, everyone laughed. Everyone except Harry and Hermione. She knows what it's like to be bullied, and laughed at.
Soundlessly, Snape snarled at the class, teeth on only one side of his face flashing. Then he revealed spiders - great big hairy things. Poor Ron. Harry thought sympathetically. Snape wouldn't be doing this to him if he'd known. It's one thing to want to grind my bones for bread but Ron's... just been persistently Ron.
"One at a time, you will approach the spider given to you. I warn you, these tarantulas are quite poisonous. Then you will cast all three of the Unforgivables on it. Since you think it's so funny that one of mine finds them hard to cast, I defy you to do better."
Harry didn't need to think, not really, after that display of verbal venom. No one, if they knew what was good for them, would be actually casting those spells today. The non-Slytherins because they didn't want people thinking they were turning evil, and the Slytherins because, well, they didn't want to be known as That Bad.
And so it went, with the most interesting thing about the class being Snape's persistent goading. "Is it hard for you, Mister Finnegan?" The pretended sympathy was worse than his normal acerbic humor.
Until Snape came to Hermione Granger, who he asked, "Miss Granger, would you like to demonstrate for the class?"
"I would not." Hermione Granger said, "Two of those spells are immoral, and I won't be a participant to degredation.'
Snape's eyes flicked to Harry.
Oh, what the hell. "I agree with Hermione. If you must watch me destroy the spider, I'll make use of other means." Harry felt his mouth curl into a broken sort of smile, "After all, if I can't crucio Bellatrix Lestrange, who murdered my Godfather in cold blood, who else can I kill?"