HP: Too Late, System! I’m Already the DADA Professor

In the end, it all came down to mindset.

If you planned to live as an ordinary wizard after graduation, there was nothing wrong with thinking inside the box. But the students who chose Defence Against the Dark Arts were likely headed for far more dangerous jobs. In those moments, a different way of thinking could mean the difference between life and death.

Because Wood was the first to break through the door, he naturally got to enter the classroom first. Some students grumbled, but no one dared object.

The moment he stepped inside, the door slammed shut behind him, plunging him into pitch darkness. Douglas, who'd entered with him, had vanished without a trace.

He quickly drew his wand.

"Lumos!"

By the wand's glow, he realized he was standing at the edge of a lake. Everywhere else was water—except for the small patch of dry ground beneath his feet.

He shone his light toward the lakebed and immediately spotted a dozen corpses drifting below. His knees nearly buckled.

He stumbled back a few steps, heart pounding.

"Inferi! The professor actually brought in Inferi!"

But beneath the fear, a flicker of excitement sparked. The textbook was crystal clear about Inferi: they had no life, no soul, and no thought. They feared fire and light.

Now, the challenge was how to lure them up.

Wood swept his wand around and soon spotted a rope trailing beneath the water, stretching to the far shore. Summoning his courage, he grabbed the rope and yanked. In the mist across the lake, a small boat began gliding toward him.

As a seasoned Quidditch Keeper, he noticed something else: as soon as the boat moved, the Inferi at the lake bottom started drifting his way.

Excitement and terror warred inside him.

One hand clutched his wand, the other gripped the rope, ready to strike at a moment's notice.

He didn't have to wait long. The nearest Inferius broke the surface first.

Wood reacted instantly, dropping the rope and brandishing his wand.

"Incendio!"

A jet of fire shot from his wand, racing across the lake in an attempt to form a blazing barrier.

But Mr. Wood had forgotten a key detail: unless you used truly powerful fire magic, ordinary flames still obeyed the laws of nature. His fire hit the water with a hiss—except for the poor rope, which caught alight, the flames fizzled out almost instantly.

In the shadows, a seventh-year student scribbled another note in his little book, observing every move.

Standing beside him, Douglas watched as Wood tried again, hurling fire directly at the Inferi. This time, the creatures simply dove beneath the surface, evading the flames.

Douglas sighed quietly.

"Thank Merlin he's only a sixth-year. If he were seventh, I'd make him repeat the year. Without powerful magic, you need to adapt your spells to the situation."

The seventh-year Slytherin note-taker shot Wood a contemptuous look and boasted,

"I learned a family fire curse from my father—perfect for this sort of thing. Ordinary wizarding families just can't match the private tutoring we pure-bloods get."

Douglas's eyes went cold.

"Fiendfyre isn't some glorious family secret. The last wizard who tried to claim it as his family's legacy burned his whole house down!"

That shut the Slytherin up fast.

After fending off two waves of Inferi, Wood's challenge ended in failure. Douglas didn't hesitate to mark him with a P.

He reset the scene, had the students recharge the Inferi, and called in the next challenger.

Of course, the Inferi in the lake weren't real—they were fakes, conjured by Douglas using Transfiguration and a few hybrid spells. He'd considered bringing in an actual Inferius for the students to see, but Professor McGonagall had flatly refused to allow something so dangerous and inhumane into Hogwarts.

In truth, defeating the fake Inferi was simple: cast an extra-large Lumos and flood the lake with light. The Inferi would never come near the surface.

But magical habits die hard. Wizards are creatures of tradition—when faced with Inferi, nearly everyone instinctively reached for a fire spell, seeking the comfort of attack magic. They forgot that Inferi are, at heart, creatures of darkness.

After Wood left, he kept the true solution to himself. After all, Douglas had made it clear: whoever scored highest would be class representative. Even if he didn't want the job—being Gryffindor's Quidditch Captain was busy enough—he still hoped the honor would go to someone from his house.

The class ended, and not a single student had thought to use light against the Inferi. Every one of them blundered in with fire spells. Dolohov even tried to unleash an out-of-control Fiendfyre.

Thank goodness Douglas was quick—he hit it with a Finite Incantatem before the flames could spread. But by then, Dolohov's hair was so singed it curled in tight little ringlets.

Without hesitation, Douglas docked Slytherin fifty points.

"Mr. Dolohov, you'll write a five-foot-long self-reflection and hand it to your Head of House, Professor Snape. And you'll copy the Hogwarts school rules two hundred times."

He fixed Dolohov with a stern look.

"You have any idea how dangerous your mistake was? I'm doing this for your own good. Out-of-control Fiendfyre would've destroyed more than just this classroom—who knows how many students would've perished in the flames. Hmph! Don't give me that look. Remember, there were other Slytherin seventh-years here besides me…"

For the first time, Dolohov looked genuinely afraid. Douglas could see the fear in his eyes at last. And who could blame him? The other seventh-years had been terrified too, when the Fiendfyre went wild.

Bullying had always existed at Hogwarts—especially in Slytherin, where bloodline, year, and strength could all become excuses for torment. Douglas had no intention of meddling in their internal affairs. He doubted that, as a young Muggle-born professor, his words would carry much weight outside the Defence Against the Dark Arts classroom—unless he used force.

The bell rang, and the Gryffindors left the dungeons, arms slung around each other's shoulders.

Just as Douglas was about to leave, he spotted Professor Snape standing coldly in the corridor, eyes fixed on the classroom.

Douglas rubbed his nose. Well, time to be polite.

"Hi, Professor Snape! Haven't seen much of you this week. How are you?"

Snape shot Douglas a chilly glance and said nothing.

Then, turning to Dolohov, who still lingered by the classroom door, he snapped,

"Mr. Dolohov, must I invite you over?"

Douglas watched, clicking his tongue in silent admiration. Now that was true teacherly authority. "Must I invite you over?" He could never pull off that sort of icy command—far too cold-blooded!

Dolohov shuffled over, trembling, and stood meekly before Snape.

Snape gave a contemptuous sniff, then addressed Douglas:

"Professor Holmes, I heard every word of your little arrangement... Fifty points! Well deducted."

At the tone in Snape's voice, a chill ran down Douglas's spine.

Was he about to defend his house?

~~~❃❃~~~~~~~~❃❃~~~

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