Before Harry had time to blink, Snape had whisked them both into his office. With a wave of his wand, the desk and chairs moved out of the room (there were neat little closets that opened up, beneath some shelving, to accommodate).
"Well, Mister Potter," Snape said, stretching himself up to his full height, "You claim that potion has had a quite remarkable effect on physiological function. Shall we put you through your paces?"
Harry knew better than to answer that question - and the stinging hex that flew through the air (aimed at his heart) told him he'd understood. It wasn't a real question, simply a prelude to obtaining the answer.
Like many answers, this one required a full diagnostic. At this point, Harry wasn't even using his wand (hadn't drawn it, really), but was simply focused on Don't get hit.
Spells crossed the room, and Harry wielded magic as much as he did agility - for handholds, and the occasional cushioning spell. Those weren't cheating, not really. It wasn't like Snape was shy about such matters - if he'd wanted Harry to bruise himself, - or likely break an arm, he'd have jolly said so!
Harry still wished for cover, though, particularly when Snape started casting more than one at once. It was one thing to defend against a wand tip - in general, most spells flew conveniently straight. Snape, though, often used his left hand - and when casting wandlessly too. At least for most spells, he wasn't able to cast behind clothing. If that was the case, Harry'd been done for.
If Snape had just been assessing Harry's hand, this would have been easy.
But nooo, Snape had fixed quite a few different marks - scars, whatever you want to call them.
So this was a test of agility, running nearly at the speed of thought.
Harry slid under the next spell (a stinging hex) and then flat out blocked the Bombarda (If he hadn't, it would have got the wall, and that had Potions Ingredients in Glass Jars - and wouldn't that have been a good Learning Experience?). He twisted, as Snape tried a bodybind (that was a long incantation, not that Snape was particularly going easy - it was to give him time enough to twist out of the way, if he would).
"Enough," Snape said, smirking, "It looks like the potion has worked." His voice turned graver, "However, you're still operating under the limitations you know," Snape got a smug look on his face, "Except, of course, when you're desperate. A Gryffindor tendency to throw caution to the wind?"
Harry shook his head, responding even if it wasn't a question, "No. In a fight, getting hit could spell death. Caution is best used when you have time to think. In a fight, it's entirely appropriate to take the bloody-minded route."
Snape nodded, just slightly, and gestured. His desk and chairs came marching back out.
"Sit," Snape said, and Harry did, noticing as Snape sat, that his professor did actually appear tired (and sweaty). He's been controlling his breathing! Harry's mind hissed in a quiet sort of victory. Better learn that.
"Would you care for something to drink?" Snape asked.
"Yes sir," Harry said.
Snape smirked, and two identical mugs appeared (in Slytherin green, rimmed with silver). Inside was something dark, and steaming.
Harry took a sip, feeling the familiar bite of strong black coffee - and then his nose picked up on the aromatic scent of alcohol. "Um, sir, did you mean...?" Harry asked, inarticulate both from 'not quite sure how to question Snape of all people' and 'shite, I already had a sip!'
[a/n: As with everything, Snape always has a reason. Leave a review?]