"Mr. Longbottom? Is there something you need at this hour?"
Sherlock looked at the boy who had entered and asked softly.
The sky outside had already darkened. Although curfew hadn't started yet, it clearly wasn't long before Filch would start catching people.
Neville looked as if he hadn't recovered from his cold; his face was unnaturally pale, and he seemed quite sickly.
"P-Professor..."
he said hesitantly.
"Could I, could I ask you about a spell?"
Hearing his words, Sherlock's brow furrowed slightly. He sensed that not only was Neville's physical state off, but his mental state seemed somewhat abnormal as well.
"Of course, but what spell are you so anxious to ask me about?"
"It's, it's the Incendio Charm. Whenever I use it, it never works. I feel like my wand movements are a bit off, but I just can't find the feeling described in the books."
Neville's voice was very small, hardly louder than the buzz of a mosquito, but he described the reasons why he couldn't cast the spell very clearly. It was obvious he had been studying the Incendio Charm diligently.
Sherlock didn't answer his question directly, but instead asked with a calm expression,
"The Incendio Charm doesn't seem like a spell a second-year needs to master, does it?"
Neville tried hard to appear calm, but his amateur acting still allowed Sherlock to notice his darting eyes.
"L-Lately, the weather has been getting colder and colder. The fireplace in the Common Room keeps going out, so I wanted to learn the Incendio Charm. That way, when the fireplace goes out again, we won't have to ask the older students for help." (TN: Isn't the fireplace magical?)
His reason seemed plausible, but it was actually very flimsy.
Even if Sherlock hadn't noticed Neville's previous abnormal behavior, he could tell now that this wasn't the truth.
In Gryffindor, Neville was something of an outlier. Among a group of little lions, he always seemed to be the most timid and never one to stand out.
Therefore, what he had just said wasn't something his personality would lead him to do.
"Is that the truth, Mr. Longbottom?" Sherlock stared into Neville's eyes, not letting his wandering gaze escape his own.
Hearing his doubt, Neville seemed to grit his teeth, enduring some kind of pressure, before finally saying,
"Yes, Professor. I'm just interested in the Incendio Charm and want to light the fireplace."
Sherlock met his gaze quietly. This time, Neville persisted without looking away, a trace of indelible determination hidden within his weakness.
After a long silence, Sherlock finally shook his head gently.
"Alright, first show me how you normally practice the Incendio Charm."
Neville looked at Sherlock gratefully and immediately performed the wand movements for the Incendio Charm he had been practicing, letting him correct his actions.
"This flick shouldn't be raised too high. At the same time, your hand must remain steady without any trembling. Only then will the Incendio Charm be stable and not spark everywhere, potentially burning you."
Sherlock had specifically studied these common spells for so long that he was naturally a professional.
He easily pointed out the flaws in Neville's casting gestures and corrected his pronunciation.
Neville seemed a bit clumsy, but he learned quite seriously—more seriously than he ever had before.
Under Sherlock's step-by-step guidance, he finally mastered the basics of the Incendio Charm before curfew began.
Looking at the flames erupting from the tip of his wand, Neville bowed to Sherlock in a slightly stiff manner.
"Thank you, Professor Cavendish. Thank you very much."
Sherlock just looked at him and said meaningfully,
"If there's anything you feel you can't handle on your own,
you can come to me, Neville. You're only twelve years old right now. I am your defence against the dark arts professor. There are things you cannot face, but I can."
Neville heard his words and pursed his lips tightly, seemingly struggling with something, but he still insisted,
"I don't have anything I can't handle, Professor. If I do, I will certainly come to you for help."
Neville left Sherlock's office.
Watching the door being carefully closed, Sherlock didn't resume organising his clues.
Neville's abnormal state had clearly aroused his suspicion.
He began to recall the start of the school year at Hogwarts, when he first encountered Neville in the castle corridor. The crescent moon mark on his arm had sent a very clear burning sensation.
Although that feeling had only lasted a fleeting moment, the mark had only reacted three times, and he remembered each one clearly.
Neville's behaviour definitely suggested he was hiding something.
Since he was determined not to speak, Sherlock had no way to force him.
The magic that can peer into a person's thoughts—Legilimency—wasn't something easily learned.
At least, the current Sherlock had not yet mastered it.
However, this didn't mean he would give up his investigation of Neville. If his abnormality was related to the Basilisk in the Chamber of Secrets, then something would surely be visible from his movement patterns within Hogwarts.
Sherlock took out the Marauder's Map he had confiscated from the Weasley brothers and marked the small black dot representing Neville as a priority. In the coming days, he would observe Neville's actions at any time.
His original promise to George and Fred that he would return the Marauder's Map to them by Christmas would likely have to be delayed a little.
Now, not only did he need to use the Marauder's Map to monitor Neville's movements, but he also had to study how to remove his own mark from the map.
After all, even if he were to return it to the twins, he couldn't allow them to monitor him through the map.
Once he finished these two tasks, he would keep his promise and return the Marauder's Map to its original owners.
Back in the dormitory, Neville was still as listless as usual.
In the dormitory, Harry and Ron had unusually gone to bed early today. Seamus was still catching up on his homework for tomorrow's Potions class. Seeing Neville enter, he asked curiously,
"Where did you go, Neville? I didn't see you in the Common Room just now."
"I went to the library to return some books." Neville's voice was still weak, and Seamus didn't notice anything wrong.
As the night deepened and midnight approached, everyone else had fallen into a deep sleep. On a four-poster bed with curtains drawn, a figure suddenly sat up.
He shakily pulled something out from under his bed, then carefully walked out of the dormitory and into the pitch-black Common Room.
Groping in the dark, the figure reached the fireplace in the Common Room, threw what he was holding into the hearth, and then waved his wand.
"Incendio!"
The suddenly ignited flames filled the entire fireplace. The orange-yellow light leaped in the dark Common Room, illuminating Neville's pale face.