Empty Defense Classroom, (Oct 1 st )...
"Engorgio," Harry said, jabbing his wand at a nearby desk. A blueish-green spell shot out of his wand and made contact with the desk; however, instead of causing the desk to grow, the spell caused the back of the desk to explode, showering the back wall with splinters of broken wood.
"Damn," Harry cursed for what seemed like the tenth time. All around him were fragments of broken wood. Each and every deformed piece of furniture demonstrated the young man's failure at properly casting the growth charm.
Going back to his open charms book, Harry made sure he was doing everything right. A clockwise swirl of the wand followed by a solid thrust forward while incanting the spell as in-gore-gee-oh. He was doing everything right! Why wasn't the spell working?
Closing the book, Harry turned to face one of the few remaining desks. With a clockwise swirl, followed by a sharp jab forward, Harry angrily snapped out, "Engorgio."
This time the spell's color was a tad bit bluer, and when it made contact with the piece of furniture, the desk shook for a moment before violently exploding. Harry had to dive behind the teacher's desk to avoid several large pieces of flying debris from hitting him.
Muttering about doing everything the book said, Harry was prepared to give up for the day when he heard the sound of clapping coming from behind him. Reluctantly turning around, Harry found himself staring at Professor Quirinus Quirrell, the resident Defense Against the Dark Arts teacher.
Harry hung his head. Not only did he completely fail at mastering the growth charm, but now he was likely to have his first detention for damaging school property and using magic in an unsupervised classroom.
"Q-q-qu-uite the explosion, Mr. P-P-Potter," Quirrell said with his usual stutter, "I am a little s-s-surprised t-t-t-t-to see all the damage you've d-done. S-s-surely you didn't do all this with one sp-sp-spell?"
"No, sir," Harry said, realizing the futility in lying since he was caught red handed. "I had a silencing charm on the room, and I've been practicing for an hour or so."
Quirrell seemed slightly surprised. "I wa-wasn't aware that s-s-silencing charms were f-f-f-first year spells."
Harry shrugged. "I guess I'm a little ahead."
"And what caused all this?" Quirrell asked, gesturing to all the destroyed property.
"An engorgement charm," Harry said, embarrassed at his inability to properly cast the spell.
Quirrell paused for sometime, as if debating something within himself, before saying, "Show me." With a wave of his wand, all the broken desks quickly fixed themselves. Quirrell then levitated one desk away from all the others and gestured for Harry to cast the spell.
Stepping forward, Harry perfectly demonstrated the wand movement and incantation for the engorgement charm. The spell left Harry's wand and impacted the desk, causing it to shake momentarily before violently exploding.
Harry, once again, found refuge behind the teacher's desk, but Quirrell simply raised a shield and allowed the pieces of wood to impact it. "A g-good a-attempt, Mr. Potter," Quirrell admitted, "but do you know w-what y-you did wrong?"
Harry came out from behind the teacher's desk with a scowl on his face. "No. I did the wand movement right, and I know I'm saying the spell correctly."
"True."
"So what am I doing wrong?" Harry demanded. "It should work."
"W-what is th-the most important rule of m-m-m-magic?" Quirrell asked.
After a long pause, Harry reluctantly said, "I--I'm not sure."
"Intent," Quirrell said sharply. "You need to visualize the desk growing, becoming larger. Without intent, your magic is unfocused and chaotic."
"Intent," Harry muttered to himself as he recalled what Flitwick had told him about not needing a specific spell to close his door. "Alright, intent. I can do this."
Harry turned his attention on an isolated desk in the corner of the room. "Engorgio," he said, focusing on the desk becoming larger. The spell impacted the desk and it began to shake, but this time the desk grew several feet until it was large enough to easily seat Hagrid.
"Congratulations, Mr. Potter."
"Thank you, sir," Harry said, very proud of his achievement. "Um, sir, I'm not in trouble, am I?"
"No," Quirrell said after giving Harry an uncharacteristically piercing look.
"Sir," Harry called out as Quirrell made to leave the room, "sir, if you wouldn't mind, um, well, what I mean to say is...if you have the time, sir, do you think you could teach me?"
"I am already teaching you, Mr. P-P-Potter," Quirrell said somewhat sarcastically.
"No, well, yes sir," Harry said. "But I meant in private. Just the two of us. I asked Professors Flitwick, McGonagall, and Snape, and they all said I'm too young, but I –"
"Mr. Potter, you are a f-f-f-first year."
"I can do it," Harry said sharply. "That was a third year charm, and I managed to cast it."
"Only with my help," Quirrell said with a small grin.
"Well, I suppose that's true, but I still did it. Please, sir? I'll learn anything you want to teach me, please?" Harry practically begged.
Quirrell peered at Harry for sometime before he closed his eyes in deep thought. Slowly, he began to nod his head. "Very well, Mr. Potter, but you will do exactly as I say. Understood?"
Harry couldn't keep the large smile off his face as he nodded his head. Quirrell might not be the best teacher in the school, but he clearly knew a bit about magic. Besides, if Quirrell turned out to be a bad teacher, he could always just go back to learning on his own.