Honestly, Lupin had only given Moody a quick rundown of the curriculum from the first to seventh years. He didn't spend much time on the fourth year (who were third years last year), since their learning pace was... well, it was a bizarre anomaly in Hogwarts' teaching history.
The fifth and sixth-year students weren't even as far along as the fourth years (last year's third years) were.
It was all because that year had a Disciplinary Committee that was unbelievably competitive. They were pushing each other so hard it was ridiculous.
"Excellent. You lot are really something else," Moody said, his voice a little dry.
He was becoming more and more surprised as he listened to the students chattering about their progress. He genuinely had no idea what he could possibly teach them.
But the students at the front of the class looked a bit ashamed. "Professor, we're still miles behind you. We haven't even learned how to deal with a Dark wizard yet."
Moody: ...
That was just a figure of speech. Even in the old days, when Dark wizards were a huge problem, they wouldn't have expected a fourth-year Hogwarts student to fight one.
This wasn't like the much more chaotic era from a hundred years ago.
Moody cleared his throat a few times and shifted the topic back to Defence Against the Dark Arts. He had to do something shocking to get these kids' attention.
---
"So, does anyone know which curses receive the most severe punishment under wizarding law?"
Ron's eyes lit up. He knew this one!
He raised his hand faster than Hermione. "The three Unforgivable Curses!"
"The Imperius Curse, the Cruciatus Curse, and the Killing Curse."
"Very good, very good. An excellent answer." Moody praised him again and motioned for him to sit down.
"What about house points?" Ron wondered. "Where are the house points? Even one would do."
Ron blinked, seeing that Moody had no intention of awarding any points. He decided right then and there that he'd be cursed before he answered another question.
"The Imperius Curse caused the Ministry of Magic a great deal of trouble back in the day," Moody said, pulling a clear jar with a spider inside out of his pocket.
"Imperio!"
Moody took the spider out and tapped it lightly with his wand. The spider began to do a tap dance, like a puppet on a string.
He had expected the students to burst out laughing. That's what the older students, even the seventh years, had always done.
But to his surprise, the fourth-year students all stopped smiling and watched the spider with serious, focused expressions.
"It's a terrifying curse. It can turn the person it's cast on into a puppet."
"My dad told me about this curse. It can make a person completely controlled, make them do whatever you want... even die."
"Is there any way to break this curse?"
"My aunt, who works at St. Mungo's, said there's a way... but it's a complicated brain treatment. If anything goes wrong, the person could be left permanently damaged."
"So how do you know if someone is under this curse?"
"I remember hearing Mr. Dursley mention that you can tell by their eyes."
In theory, it's fairly easy to tell if a wizard is under the Imperius Curse.
The simplest way is to see if their eyes have any focus.
Most people just don't pay attention to that detail.
As he listened to the students' discussion, Moody's face remained expressionless, but he was astonished.
Were these kids really just fourth years?
The way they were thinking about these problems would make the seventh years blush with shame.
And it didn't end there.
The students soon posed a difficult question to Moody.
"Professor Moody, if we get hit with the Imperius Curse, is there any way we can break free on our own?"
Break free from the Imperius Curse on your own?
That was a great question.
But unfortunately, he didn't know the answer. He only knew how to cast the curse on others.
His knowledge of Dark Arts was all about how to use them.
"I'm afraid that so far, the number of wizards who have been able to break free of the Imperius Curse on their own is zero."
After hearing Professor Moody's answer, the students gained a new understanding of the curse.
But at the same time, new questions began to pop up.
"Professor Moody, is there any way we can avoid or resist the Imperius Curse?"
Most wizards can't resist the Imperius Curse unless they have a will of steel. Otherwise, they're nothing but a sitting duck against it.
Moody thought for a moment before answering, "It's very difficult. The chance of success is almost zero."
"Professor Moody, if someone is under the Imperius Curse... can we use a new Imperius Curse to control them instead?"
This question was more insightful than the first two.
If one of your allies is controlled by an enemy, can you regain control?
Faced with this question, Moody took even longer to think. "You can... but your mastery of the Imperius Curse must be much greater than the other person's."
The same would be true if three people cast the Imperius Curse on one person at the same time—it would depend on whose mastery of the curse was the most powerful.
Seeing the students ask one question after another, and with the difficulty increasing, Moody quickly changed the subject. "That's enough chit-chat. I think you should all get a look at the next of the three Unforgivable Curses."
If they kept asking, he'd have nothing left to teach them.
He was here to teach, not to hold an academic symposium.
What was the next curse?
To give the students a better view, Moody cast an Enlarging Charm on the spider.
The spider instantly swelled to four or five times its original size.
The students could clearly see every tiny hair on its legs.
Moody aimed his wand at the spider again.
"Crucio!"
With the clear incantation, a sickly green light shot from the tip of his wand, hitting the enlarged spider.
The spider's eight legs instantly curled up, clinging to its body to form a ball. It flipped over, its body twitching violently and shaking from side to side. All the students knew this was a struggle of extreme pain. If it had vocal cords, it would be screaming its head off right now.
But this was just a regular spider, not one of the dangerous, five-X-rated Acromantulas that could speak.
So it couldn't let out a single wail.
Moody didn't take his wand away. As the curse lasted longer, the spider began to tremble and convulse even more. The students watched a shocking sight: the spider started to tear off its own legs, one by one.
"Please stop, Professor Moody!"
The students' pleas didn't make Moody let go. Instead, he kept casting the spell, looking like a mad scientist.
He didn't stop until the spider had ripped off all eight of its legs, leaving only a body and a single breath of life.
"Extreme pain. A person hit with the Cruciatus Curse will feel a kind of agony they've never known before... This isn't just physical pain, it's pain from the very depths of their soul."
Moody said this softly. The entire classroom was silent. The students seemed to have been frightened by his actions.
"Now, if you have any questions, you can ask them."
Just as Moody was feeling pleased with himself, the students' answer completely took him by surprise.
"Professor, we couldn't see it clearly... your body was in the way."