Harry strode into Defense like he owned the place, more like he was going to be the teacher than deferential to Snape. He collected people into his gaze, Slytherins scattered here and there - for all that 'Slytherins Stuck Together' was a mantra, they didn't really cleave to it much, other than defending each other.
Hmm... perhaps he could use that. The Hufflepuffs had formed two groups - one primarily female, the other mostly male. Justin was the odd one out. The Ravenclaws had merged with the Gryffindors (and who knew how that had happened, Harry mentally put money on Hermione).
Before Harry could as much as start a little plotting, Snape strode through the door, his pace disorganized, but still as swift as ever. He tottered faster than many ran. It was impressive, in its own way.
"Read the chapter on Darkly Magical Beasts. Now that you aren't being taught by one, perhaps you can quiz each other on the subject." Snape drawled, practically laying down on the podium, his whole upper body weight supported by one arm - that had a slight tremble to it.
Harry belatedly heard the bait in Snape's comment, his eyes quickly flicking to Hermione and Ron, both of whom looked fit to charge up to Snape and holler at him. That, would be a bad idea in so many ways, Harry thought grimly. Mentally, he flagged where Parkinson was, and swirled his wand in his hand, wordlessly casting a mirror charm at two discrete points in the room. Then, he flicked a stinging hex at the first - it ricocheted into the second, and wound up speeding by Parkinson and hitting Ron in the arse. Luckily, Lavender was beside him, to calm him down before he exploded in front of the whole class.
The war had started off cold.
Pansy didn't know what hit her, of course, but Ron's wordless stinging hex didn't go unavenged. Ol' Pugface sent a stinging hex towards Lavender Brown, who subsequently sent a tickling hex at Parvati - and then they both, from opposite sides of the room, tried to get Pansy, using some sort of archaic "girls only" handspeak.
Pansy, who was substantially more prepared, simply ducked - more accurately, bending down to tie her shoelace. How she'd managed to untie it while standing...
Pansy had been near two groups of Hufflepuffs, and Hannah Abbot wasn't known for her temper. Zach was more inclined to take it as "who DARES to hex me from behind?", but that didn't matter in the grand scheme of things.
Snape's eyes were closed, but Harry knew that was just the illusion of letting them get away with it.
Still, as Zach and Hannah started shooting the Tango hex, as well as a modified tickling curse that wouldn't stop until you peed yourself, Harry snuck in a few more stinging hexes, bringing Goyle, and - oddly, the usually rational Hermione into the mix. (Hermione was probably just upset that someone was interrupting her studying.)
[a/n: This is the magical equivalent of throwing spitwads around the classroom. Scuffly, but not dangerous. And it is Defense, not the hallways. Reviews make me write more!]