"Mr. Potter, all things have their accustomed uses. Give me ten unaccustomed uses of objects in this room for combat!" For a moment Harry was rendered speechless by the sheer, raw shock of having been understood.
And then the ideas started to pour out.
"There are desks which are heavy enough to be fatal if dropped from a great height. There are chairs with metal legs that could impale someone if driven hard enough. The air in this classroom would be deadly by its absence, since people die in vacuum, and it can serve as a carrier for poison gases."
Harry had to stop briefly for breath, and into that pause Professor Quirrell said:
"That's three. You need ten. The rest of the class thinks that you've already used up the whole contents of the classroom."
"Ha! The floor can be removed to create a spike pit to fall into, the ceiling can be collapsed on someone, the walls can serve as raw material for Transfiguration into any number of deadly things - knives, say."
"That's six. But surely you're scraping the bottom of the barrel now?"
"I haven't even started! Just look at all the people! Having a Gryffindor attack the enemy is an ordinary use, of course -"
"I will not count that one."
"- but their blood can also be used to drown someone. Ravenclaws are known for their brains, but their internal organs could be sold on the black market for enough money to hire an assassin. Slytherins aren't just useful as assassins, they can also be thrown at sufficient velocity to crush an enemy. And Hufflepuffs, in addition to being hard workers, also contain bones that can be removed, sharpened, and used to stab someone."
By now the rest of the class was staring at Harry in some horror. Even the Slytherins looked shocked.
"That's ten, though I'm being generous in counting the Ravenclaw one. Now, for extra credit, one Quirrell point for each use of objects in this room which you have not yet named." Professor Quirrell favored Harry with a companionable smile. "The rest of your class thinks you are in trouble now, since you've named everything except the targets and you have no idea what may be done with those."
"Bah! I've named all the people, but not my robes, which can be used to suffocate an enemy if wrapped around their head enough times, or Hermione Granger's robes, which can be torn into strips and tied into a rope and used to hang someone, or Draco Malfoy's robes, which can be used to start a fire -"
"Three points," said Professor Quirrell, "no more clothing now."
"My wand can be pushed into an enemy's brain through their eye socket" and someone made a horrified, strangling sound.
"Four points, no more wands."
"My wristwatch could suffocate someone if jammed down their throat -"
"Five points, and enough."
"Hmph," Harry said. "Ten Quirrell points to one House point, right? You should have let me keep going until I'd won the House Cup, I haven't even started yet on the unaccustomed uses of everything I've got in my pockets" or the mokeskin pouch itself and he couldn't talk about the Time-Turner or the invisibility cloak but there had to be something he could say about those red spheres...
"Enough, Mr. Potter. Well, do you all think you understand what makes Mr. Potter the most dangerous student in the classroom?"
There was a low murmur of assent.
"Say it out loud, please. Terry Boot, what makes your dorm-mate dangerous?"
"Ah... um... he's creative?"
"Wrong! " bellowed Professor Quirrell, and his fist came down sharply on his desk with an amplified sound that made everyone jump. "All of Mr. Potter's ideas were worse than useless!"
Harry started in surprise.
"Remove the floor to create a spike trap? Ridiculous! In combat you do not have that sort of preparation time and if you did there would be a hundred better uses! Transfigure material from the walls? Mr. Potter cannot perform Transfiguration! Mr. Potter had exactly one idea which he could use immediately, right now, without extensive preparation or a cooperative enemy or magic he does not know. That idea was to jam his wand through his enemy's eye socket. Which would be more likely to break his wand than kill his opponent! In short, Mr. Potter, I'm afraid that your proposals were uniformly awful."
"What?" Harry said indignantly. "You asked for unusual ideas, not practical ones! I was thinking outside the box! How would you use something in this classroom to kill someone?"
Professor Quirrell's expression was disapproving, but there were smile crinkles around his eyes. "Mr. Potter, I never said you were to kill. There is a time and a place for taking your enemy alive, and inside a Hogwarts classroom is usually one of those places. But to answer your question, hit them on the neck with the edge of a chair."
There was some laughter from the Slytherins, but they were laughing with Harry, not at him.
Everyone else was looking rather horrified.
"But Mr. Potter has now demonstrated why he is the most dangerous student in the classroom. I asked for unaccustomed uses of items in this room for combat. Mr. Potter could have suggested using a desk to block a curse, or using a chair to trip an oncoming enemy, or wrapping cloth around his arm to create an improvised shield. Instead, every single use that Mr. Potter named was offensive rather than defensive, and either fatal or potentially fatal."
What? Wait, that couldn't be true... Harry had a sudden sense of vertigo as he tried to remember what exactly he'd suggested, surely there had to be a counterexample...
"And that," Professor Quirrell said, "is why Mr. Potter's ideas were so strange and useless - because he had to reach far into the impractical in order to meet his standard of killing the enemy. To him, any idea which fell short of that was not worth considering. This reflects a quality that we might call intent to kill. I have it. Harry Potter has it, which is how he could stare down five older Slytherins. Draco Malfoy does not have it, not yet. Mr. Malfoy would hardly shrink from talk of ordinary murder, but even he was shocked - yes you were Mr. Malfoy, I was watching your face - when Mr. Potter described how to use his classmates' bodies as raw material. There are censors inside your mind which make you flinch away from thoughts like that. Mr. Potter thinks purely of killing the enemy, he will grasp at any means to do so, he does not flinch, his censors are off. Even though his youthful genius is so undisciplined and impractical as to be useless, his intent to kill makes Harry Potter the Most Dangerous Student in the Classroom. One final point to him - no, let us make that a point to Ravenclaw - for this indispensable requisite of a true fighting wizard."
