Setting aside the relationship between Snape and the Malfoy family for the moment.
Looking only at the tangled history between Harry Potter and Snape, it should have been very difficult for Harry Potter to even come into contact with a spell like Sectumsempra, let alone master it.
Because behind every powerful spell, there may be a family's interests and inheritance at stake. Only with those things can such families remain above the vast majority of wizards for generations.
After all, spells are a kind of resource.
Having grown up in that kind of environment, Pansy and Astoria naturally understood the hidden implications better than anyone else.
That was why, the moment they heard Harry Potter might be able to learn Sectumsempra, their expressions turned so grave and shocked.
Because what they saw was far more than the small part Hermione could see...
Although Hermione knew Sectumsempra had been created by Severus Snape, she did not understand the full seriousness of it, so she began analyzing the possibilities.
"Could it have been Dumbledore's request? I think even Professor Snape might not be able to refuse him."
"Hah? Don't be ridiculous. Sectumsempra isn't some spell for pranks. It's a powerful piece of dark magic. How could it possibly be handed over to someone else that easily?"
"That's why I don't think Dumbledore is that kind of rigid person."
"You really don't understand anything, Granger."
"...What do you mean?"
Seeing the smug look on Pansy's face, the veins at Hermione's temple started throbbing uncontrollably.
But when she noticed that Draco and the others were staying silent, Hermione gradually realized there had to be some secret here that she did not know.
Watching Pansy and Hermione, who had been on the same side a moment ago and then turned into enemies again the next second, Fleur smiled, clearly entertained.
Perhaps because of Draco, Fleur found she was not nearly as put off by them as she had imagined.
In fact, for someone who had always found it hard to make true friends, she even envied the relationship between them...
...
Just as Pansy was explaining the reason to Hermione,
Draco turned his attention to Fleur. He had a great many questions he wanted to ask.
He lightly tapped the floor with his cane. "Any new news from Father's side?"
"Mm, not really. There's not much worth mentioning. But our allies have run into quite a bit of trouble lately."
"You mean... the Ministry of Magic?"
"More precisely, our cowardly Minister of Magic. With how unstable the wizarding world has been, his seat hasn't been very secure lately."
"Oh?"
"Rufus Scrimgeour."
The name Fleur mentioned made Draco think of the wizard with the sharp, piercing eyes, the Head of the Auror Office who had once tracked down Sirius Black.
An elite Auror known as the old lion.
And if Fleur had brought up Rufus Scrimgeour, then the one who had stepped forward to compete with Cornelius Fudge for the position of Minister of Magic must be that old lion who commanded the Aurors...
"If it's him, then he really could cause our Minister of Magic a great deal of trouble."
"In fact, if not for our support, the Minister of Magic might already have been replaced. After all, the Dark Lord's resurrection has made a great many people question the Ministry's competence."
"So the Ministry has now split into two factions because of the conflict between those two?"
"Exactly."
Cornelius Fudge, seated at the top and holding most of the power.
And Rufus Scrimgeour, who commanded the Ministry's strongest fighting force.
In a very short time, Draco pieced together a rough picture of the Ministry's current situation, and at the same time understood the doubts that had been puzzling him before.
"I see... So that explains why Cedric and the others were able to appear at Hogwarts."
If Cornelius Fudge was inclined to ally himself with Lucius, then Rufus Scrimgeour, who wanted to take his place, was clearly trying to move closer to Dumbledore's side.
In other words, Cornelius Fudge had already lost control of the Aurors.
Thinking of that, Draco suddenly grew curious. What kind of expression was Dolores Umbridge, the one in charge of the Three Decrees, wearing right now...?
...
By this point, Draco understood what was happening outside, as well as the choice his father and the others had made.
Surely even someone like Cornelius Fudge had something on him that could be used or bargained with.
And next, there was something else Draco wanted to know...
"Do we know now what happened with Dumbledore's injury?"
"As for that... all we know so far is that it's connected to the Dark Lord's Horcruxes. It seems he triggered a magical trap that had been set in advance."
"A magical trap? It seems that Dark Lord really does understand Dumbledore very well."
The fact that Voldemort had revived by relying on Horcruxes was no longer some enormous secret.
But what Draco was curious about was just how many Horcruxes that death-fearing Dark Lord had actually made in the first place.
Thinking of that, Draco murmured, "Maybe we should investigate how the Dark Lord first learned about Horcruxes."
As had been said before, knowledge of Horcruxes was not something an ordinary wizard would ever have the chance to come across.
Taboo.
It was always something held only in the hands of a few.
And naturally, that was true in the wizarding world as well...
Hearing Draco mutter to himself, Hermione, who had been paying close attention to this side of the conversation, suddenly spoke up.
"Even so, how can you be sure, Draco, that he learned it from someone else?"
"I don't."
"Hah?!"
Draco's answer made Hermione roll her eyes.
But then she heard what he said next.
"But don't forget that diary."
"The diary? Isn't that one of that person's Horcruxes... wait!!"
"Looks like you've figured it out too."
Draco had never doubted Hermione's intelligence or how quickly she caught on.
Pansy, who could not understand what the two of them were talking about, cut in impatiently.
"What are you two talking about? What does that have to do with the diary?"
Hermione frowned.
"Don't you know? The Dark Lord that appeared from that diary took the form of himself as a student."
And that meant...
Voldemort had created the diary Horcrux while he was still attending Hogwarts.