Voldemort stayed beside Nagini, while Cohen returned to the castle alone.
The Dementors outside the castle were still slacking off because Cohen had told them they couldn't suck the soul out of Sirius Black even if they caught him.
Time quickly arrived for Harry and Lupin's secret tutoring session. Only Cohen and Ron remained in the common room.
"Harry's going to learn the Patronus Charm because of Quidditch..." Ron said, poking a lazy fire salamander with a small twig as he asked Cohen, "But what's Hermione learning it for? I mean, Professor Lupin even said it's not something we should be learning right now—"
The fire salamander spat out a spark, instantly igniting the twig Ron was using to poke its belly.
Fred had caught this fire salamander to amuse Ron. Fire salamanders can only survive for six hours after being removed from flames, and wizards usually take their blood when they're close to dying.
But Ron wasn't that cruel. He'd release this fire salamander into the common room fireplace later.
"No idea. Maybe she wants to murder a Dementor."
Cohen yawned, lying back in an armchair.
Hopefully, Harry and Hermione won't come back all excited and show off that spell in front of me...
#IfHarryPotterMurdersARoommateAtHogwartsCanItGuaranteeOtherGryffindorsPostgraduateAdmission?#
"But it's good that Hermione's learning it too—ow!" Ron yelped as the fire salamander lightly bit him. "It bit me!"
"That means it likes you," Cohen said knowingly. "If it were impatient with you, it would probably choose to burn off your eyebrows instead of just nibbling on your finger."
The fire salamander tilted its head and stared at Ron for a few seconds, as if wanting Ron to touch it with his hand instead of the burnt twig that was now just a tiny stub.
"Then my hand would be cooked," Ron said, dragging his armchair away from it.
Seeing that Ron was so boring, the fire salamander spat a few sparks at him, then quickly hopped off the table and into the fireplace.
Meanwhile, on the other side, Harry and Hermione had also arrived at their meeting place with Lupin—the History of Magic classroom.
It was pitch black when they first entered. Hermione lit the lamps with her wand, and they only waited for five minutes before Lupin arrived with a large trunk.
"The Boggart from last time," Lupin said. "It was originally supposed to be defeated by the students in my lesson plan—but either way, this saves me the trouble of finding another one."
"Can a Boggart imitate a Dementor?" Harry asked somewhat doubtfully. "I mean... I thought it could only imitate a shape..."
"When imitating dark creatures, Boggarts will imitate the corresponding ability effects to a great extent," Hermione answered quickly, sounding like she was reciting from a book. "And the Patronus Charm can also be used to drive away Boggarts."
"Excellent answer, Hermione," Lupin said with a smile. "It's a shame this isn't a regular class, otherwise I'd definitely award Gryffindor ten points."
"Alright then," Lupin said, clapping his hands together. "Let's begin our lesson now—the spell I'm going to teach you next—as Hermione said, the Patronus Charm..."
"This is a very advanced piece of magic, far beyond the ordinary wizarding level. It's quite difficult for young wizards in terms of both magic power and control, so please be prepared," Lupin warned.
Harry and Hermione both nodded.
"What does this spell do?" Harry asked.
[Website address removed]
"It summons a Patronus," Hermione answered again. "A Patronus is a positive force, an embodiment of the things that Dementors feed on—hope, happiness, the desire to survive... But there's one thing I don't understand—Professor Lupin, if the components of a Patronus are the food of Dementors, why can it block Dementors instead of being eaten by them?"
"Because of the non-existent nature of Dementors and their dark, terrifying essence," Lupin said. "Firstly, the Patronus is the only thing that can directly interact with and harm a Dementor—only non-existence can attack non-existence."
"Secondly, the Patronus Charm contains not only happiness but also the wizard's desire to survive and protect. Its purpose is to fight back, not simply to materialize something," Lupin said. "That might sound a bit abstract. Let me explain it in a more common way. A Patronus is a weapon formed by the wizard using magic, like you guys fighting with hard baguettes—and right now, you can only hit each other with this baguette."
"Pfft—" Harry chuckled at the analogy. "What does a Patronus look like?"
"Each Patronus is unique to the wizard who conjures it," Lupin said. "You need to say an incantation, and you must focus all your thoughts on a particularly happy moment for the spell to work."
Harry and Hermione both began to recall their happiest memories.
But it's often difficult to judge which memory is "happier."
"The incantation is 'Expecto Patronum'," Lupin cleared his throat and recited the spell. "You can try it first."
Harry, on his first try, summoned a cloud of silvery mist—which suddenly reminded him of something.
"I think I saw Cohen use that!" Harry said in surprise.
Back in their first year, in the room hiding the Mirror of Erised, Harry seemed to remember seeing Cohen use this spell. Cohen had also summoned a large cloud of mist back then, except it seemed Cohen's mist stayed close to the ground, while the mist Harry had just summoned floated upwards...
"Cohen?!" Hermione's eyes widened.
"Cohen?" Lupin's expression was strange.
Harry was about to explain, but he suddenly felt it wasn't a good idea to mention his and Cohen's rule-breaking night-time wanderings to Lupin...
"Maybe it was during one of our attempts in the common room," Harry changed his story. "Cohen also seemed to conjure up a bunch of that silvery mist..."
Next was Hermione's attempt—Hermione tried several times before finally conjuring a wisp of mist, which made her look quite frustrated.
"Is that it?" After both of them managed to produce some reaction with the spell, Harry eagerly asked Lupin.
"You can't tell its effectiveness just from its form—of course, the ultimate form of a Patronus is a corporeal animal, but for you two right now, you don't need to aim that high," Lupin explained. "Are you ready to try it out on a Dementor?"
"Yeah," Harry nodded with extreme confidence.
But Harry had clearly overestimated himself—
After several attempts, he still couldn't use this formless Patronus to repel the Boggart disguised as a Dementor.
"Expecto Patronum! Expecto Patronum—"
Harry repeatedly heard the voices of his parents before their deaths, his father's shout, his mother's dying scream—death had never felt so close.
"Perhaps we should stop here for tonight," Lupin said uneasily after hearing Harry say he heard his parents' voices. "Practicing against Dementors... I shouldn't have suggested you go through this..."
"Maybe we should call it a night, Harry..." Hermione said from the side, tears welling up in her eyes. "That sounds awful..."
"No," Harry shook his head. "I want to try one more time! I'm not thinking of something happy enough, that's why..."
Until the very last time, Harry finally managed to remain standing instead of fainting under the Dementor's influence—
"Excellent! Harry, excellent!" Lupin said with relief.
"Can I try again?" Harry asked.
"No," Lupin said firmly. "Have some chocolate, Harry. That's enough practice for one night. Here—"
"Okay..." Harry sat down to the side, ready to watch Hermione practice.
"Hermione, this practice method is indeed very uncomfortable," Lupin said, turning to Hermione. "I'm worried—"
"It's okay," Hermione bit her lip. "I have to practice too—I must."
Harry didn't quite understand why Hermione was so insistent—she didn't need to play in the Quidditch match, and she couldn't offer Harry much help from the stands because they were too far away.
Lupin assumed she was doing it for her friends, which reminded him of his own school days with James, Sirius, and Wormtail.
But Cohen, who had slipped in here ten minutes earlier in his ghostly form to secretly watch the tutoring session, knew why Hermione was doing this.
Hermione knew Cohen's identity and was afraid Cohen would harm her friends—no one knew why a creature that fed on human emotions and souls would infiltrate the human community.
If Cohen only had magical creature blood, that would be one thing. Even if magical creatures were dangerous, their diet included things other than humans.
But Dementors were different—Dementors only harmed humans. That's what the books said, and even Cohen himself had admitted it.
She was currently wavering between "believing Cohen" and "being wary of Cohen," and even she wasn't sure what was right.
"Then shall we give it a try first?" Lupin asked, ready to open the cupboard at any moment. "Ready?"
"Ready..." Hermione nodded.
Lupin opened the cupboard—but what came out wasn't a Dementor, but...
"Cohen?" Harry's eyes widened as he looked at Cohen, who climbed out of the cupboard with a gloomy expression, then looked at the bewildered Hermione. "What—"
The Boggart-turned-Cohen wasn't even holding a wand, and the robes he was wearing were large and tattered—Harry didn't remember Cohen ever dressing so poorly.
"No—no—" Hermione screamed, covering her face. "I can't—"
"Riddikulus!" Lupin seemed to understand what was happening and stepped between Hermione and the Boggart.
The Boggart turned back into a deflated balloon and whizzed back into the trunk.
"What was that all about?" Harry asked, full of confusion.
"I'll handle this," Lupin said, helping to cover up the situation. "Harry, why don't you go back and rest? I need to have a word with Hermione."
"Okay... alright," Harry mumbled, seeing that neither Hermione nor Lupin was willing to explain things to him.
He was indeed quite tired now—maybe Hermione would be willing to explain the reason to them tomorrow.
"Don't—don't tell Ron and Cohen," Hermione grabbed Harry's arm and reminded him before he left.
"Huh?" Harry said in surprise. "What does this have to do with Ron—"
"Just don't tell them—" Hermione said. "You guys will find out about this eventually... but not so suddenly..."
The ghostly Cohen, who had been watching the drama unfold, furrowed his non-existent brow.
It's too easy for people to misunderstand and think Hermione has a crush on me, isn't it?!
"Alright," Harry nodded doubtfully and left the classroom alone.
Now only Lupin and Hermione, the two "living people," remained.
"Prof-Professor...?" Hermione asked hesitantly when Lupin remained silent.
"You know?" Lupin said with a strange expression.
"Know what?" Hermione tried to play dumb, but Lupin was already quite certain of his guess.
"You're learning the Patronus Charm to protect yourself from a friend, aren't you?" Lupin said.
"You know too?" Hermione said in surprise. "Or is it..."
"Most of the professors know about this. I even asked Professor Dumbledore after arriving at the school," Lupin said. "Professor Dumbledore trusts him—and I trust him too."
"I really shouldn't doubt my friends..." Hermione said guiltily. "It's just that the description of this species in the books... it's terrifying..."
"Blood often doesn't determine whether a person is good or bad," Lupin said meaningfully. "But considering the Boggart situation, your practice probably can't continue normally—why don't you get some rest? You look like you're a bit overworked..."
"Yeah," Hermione nodded and hurried out of there.
Lupin left the classroom after putting away the trunk containing the Boggart. Now only the ghostly Cohen remained.
His body was left on the bed in the dorm pretending to sleep. He wasn't in a hurry to go back.
Hermione's suspicion of him was actually a relatively important part of Cohen's plan—but she had already learned the spell, and being able to produce some silvery mist should achieve the same effect...
But what Cohen still couldn't understand was—according to his various plans, Sirius Black wouldn't be caught by the Ministry of Magic and the Dementors.
There was no foreseeable outcome where "Sirius Black is caught by the Ministry of Magic."
So under what circumstances would the future he had observed come to pass?
However, the time to verify the prophecy's outcome was approaching soon—the Hogsmeade weekend the day after tomorrow, Saturday, would be the moment to finalize everything.
Cohen floated back to his body in the dorm, arriving just as Harry returned.
"How was it? Did you learn a new spell?" Ron asked Harry curiously as he came back.
"Does this mean we won't have to worry about Dementors anymore next time?" Seamus was also very concerned about whether Gryffindor could win the Quidditch Cup.
"I know the spell, but the effect doesn't seem very obvious," Harry said uncertainly. "But I made a lot of progress tonight. I'll practice a few more times. I should be able to get it right before the Quidditch match..."
"What about Hermione? Did Hermione learn it?" Ron asked.
"She didn't try—" Harry suddenly remembered Hermione's warning.
"Why?" Ron frowned.
"She... was too tired—she had too many classes and almost fell asleep," Harry made up a reason.
"I told her a long time ago to study less," Ron shook his head and burrowed back under the covers. "If she keeps going like this, she'll end up working herself to death at school..."
Harry glanced one last time towards Cohen's bed, where Cohen was curled up in a ball.
Why did Hermione's Boggart turn into Cohen?