The Great Hall was lush with Christmas decor, snowflakes descending from the enchanted ceiling above.

Aileen isolated herself at the edge of the Gryffindor table with her friends, ready to divulge her unwitting suspicions about Professor Crowley. Maxwell, Albus, Rose, and - recently released from the hospital wing - Scorpius, all sat around her, waiting expectantly for her to explain. She'd told them that she needed to tell them something, but she was unsure how to word it.

Aileen glimpsed around, hoping no one would overhear. She leaned over her dinner plate, speaking to them in a hushed voice.

"Something happened between me and Erika," Aileen told them. "It was a few weeks ago. I had to help her get a counter-potion for the Veritaserum... and after that, we got to talking..."

"Hold on." Scorpius held up a hand. "You talked to her? Like, you two talked like actual human beings? And she didn't try to jinx you or anything?"

"It was complicated," Aileen sighed. "She needed my help, and she was trying to help me figure this whole sickness thing out."

"Have you considered that she's playing you?" Scorpius asked. "She might be trying to get inside your head and lead you away from her scent. If she's doing anything suspicious, she'd want you to snoop around elsewhere."

"And after what she did last year, you really can't trust her," Albus added, Maxwell and Rose nodding in agreement.

"I know, but... when I asked her all those questions, she was still under the influence of the Veritaserum," Aileen explained. "I really don't think she could've been lying. She said she got medicine in the mail at the beginning of the year, and the package wasn't signed. She said her parents always sign their names to her mail - which only leaves one person she could've gotten the medicine from."

"Her uncle Valefor," Rose muttered gravely. "If he sent her medication ahead of time, he must've known there'd be a virus outbreak."

"Exactly," Aileen agreed. "Which means there's another mole working for Xyler and Valefor in Hogwarts. If the sickness outbreak was just an accident, Erika wouldn't have gotten medication for it beforehand. No - someone knew this would happen, which means it was intentional."

"But..." Maxwell uttered, slowly raising his hand to intervene. "Um... this sickness isn't killing anyone. Why would they spread a sickness that doesn't kill anyone? I mean, Scorpius got better. Some of the other students have gotten better, too."

Aileen stared at him. He made a good point; if a dark wizard wanted to spread a magical disease throughout Hogwarts, why was the disease so benign? Why wasn't it killing anyone?

"Illnesses don't always work that simply," Rose informed them. "Sometimes, you may think you've gotten better, but the sickness is still inside you. Maybe stage two is the part that's supposed to kill you. Maybe the reason no one's died is because they haven't reached the full extent of the sickness yet."

They all exchanged grim faces.

"There's one other thing, too," Aileen said hesitantly. "There aren't many openly dark wizards these days, and Erika said dark wizards like to use magical creatures for their dirty work."

"That's actually true," Rose said knowingly. "Dark wizards can rely on creatures much more than humans, especially simple creatures who like to take orders."

"Well..." Aileen took a moment glimpsing around warily. "What I'm about to tell you cannot leave this table. I mean, seriously - you can never tell anyone what I'm about to tell you." Her eyes landed on Rose and Scorpius.

Albus and Maxwell already knew Crowley's secret, but Rose and Scorpius didn't. Aileen took in a heavy breath and explained.

"Professor Crowley is a vampire," Aileen whispered. "Professor Arius told me never to tell anyone. Don't ever tell anyone about this. All right?"

Rose and Scorpius both nodded, a glint of shock in their eyes.

"Wait," Rose said suddenly. "You're not suggesting that he's..."

"He's the only 'creature' in the school," Aileen sighed. "I hate to think such a thing of him, but he's..."

"He's your favorite teacher," Rose gasped. "And you think he's working for Xyler?"

"I don't know if he is or not," Aileen responded. "I hope he's not. But... there's no way to know for sure. I mean, who else could the mole be?"

"Anyone in the school," Rose argued. "Xyler and Valefor used a student last year. Maybe they're using a different student this year. There are loads of students in the school we know nothing about. You can't just assume it's Crowley because of his condition."

"Professor Crowley used to be an auror," Maxwell chimed in. "He's always nice to us, too. He wouldn't be..."

"We could ask him," Albus suggested.

Everyone stared at him.

Albus blinked. "What?"

"How would we ask him such a thing?" Scorpius asked. "Hey, Professor Crowley. Say, you're not poisoning everyone in the school under Xyler's orders, are you?"

"No... we don't ask him directly," Albus scoffed. "We just ask him what he knows about the whole thing. He's helping my dad and Professor Arius keep the school secure. Whether he's working for Xyler or not, he would know more than most of the other teachers. It's worth a try."

"He wouldn't tell us," Maxwell mumbled. "We're just students."

"He might tell one of us," Scorpius suggested, narrowing his eyes at Aileen. "You're his favorite. He'd tell you before he'd tell anyone else."

"Yeah, that's a good point," Albus agreed. "He might feel indebted to you, Aileen. He did bite you, after all."

"He did what-?" Rose gasped. Scorpius made a shush-ing motion, waving her down.

"I'll tell you something else, too," Albus said. "We never found the Founders' Fortunes for Hufflepuff or Ravenclaw. The bow and the shield are still out there somewhere, and the Sorting Hat has the ability to summon them. As long as there's a mole in the school, the other two Founders' Fortunes are in danger as well as the students."

"Fair point," Rose replied. "I hadn't thought of that."

"Where did you get this?" Maxwell asked, stroking the velvety cloth of Aileen's Shield Cloak.

"Oh... it was a gift," Aileen answered.

Then, she sparked another idea. Yes - Professor Crowley was the best person to ask about the state of the school's security, but there was one other person who might know even more. The person who gave her the cloak.

"Harry," Aileen murmured. "Albus - you could ask your father."

"Yeah, I suppose I could," Albus agreed. "I'll ask my father, you ask Professor Crowley."

"Right," Aileen nodded.

"'Allo allo, my little nosebleeds." James sauntered over to them, draping his arm over Albus and Rose's shoulders. "Everyone ready for Slytherin to bomb in Quidditch today?"

Aileen shot him a cold glare. "Gryffindor ate our dust last game. Ravenclaw is gonna feel the same pain today."

"Yeeeah, right," James laughed. "Don't get cocky, snake girl."

After James moseyed off, Aileen turned to the others and whispered.

"We'll ask Harry and Professor Crowley after Quidditch tonight. Aye?"

Her friends nodded.

The air was blisteringly cold outside.

Aileen marched onto the Quidditch field with her teammates, wrapped in two layers of clothing as well as her Shield Cloak and a thick pair of gloves. She tried to repress her troubling thoughts of Professor Crowley, paying no mind to Mad'am Hooch's start-of-game announcements and peering up at the stands. She couldn't see them from here, but she knew Samuel was here now, ready to watch his daughter's game.

Knowing her father was watching always made her a bit nervous, but she did exceptionally well last game. She'd do fine. She didn't need to worry.

The stands were full of cheering, and Aileen thought she heard music playing from somewhere. Professor Crowley was sitting beside Samuel and Harry up above, giving them an earful about the dueling club before the match started. Aileen's friends were just a few rows down from Crowley and Samuel, leaning on the balcony and waiting to see Aileen and Scorpius in the air.

Aileen gulped and mounted her broomstick, as did the others.

"Don't lose your grip," Callidus told his team. "You might get frostbitten out here. Keep a tight hold of your brooms at all times. We don't need another incident."

Aileen thought of Scorpius falling from his broom. She stole a glimpse of him, and he was mounted on his broomstick, wearing a visage of determination. He seemed to have recovered from the mystery illness. Hopefully, it was out of his system by now.

She glanced up at the stands again, trying not to think about Professor Crowley and failing. What would she do if she found out he was working for Xyler? She loved his classes and his dueling club. She loved being friends with such a skilled, outcasted teacher. What would she do if Professor Crowley turned out to be in league with the man who killed her mother?

Mad'am Hooch blew her whistle, and Aileen jumped, snapping out of her thoughts. Everyone soared into the air and whizzed about in all directions, the Ravenclaw captain seizing the quaffle and soaring off toward the Slytherin goals at once.

The Ravenclaws scored right away, causing an eruption of applause from the Ravenclaw stands. When the next round began, Callidus kicked himself into gear, flying faster than Aileen thought possible of a broomstick. For a moment, she had nowhere to go, so she floated midair, waiting for an opening so she could make a move.

This went on for a while. Nearly an hour passed by before Aileen had the chance to intervene in the game, and after narrowly dodging a bludger aimed at her leg, she scored for Slytherin. The crowd cheered from afar, and Aileen wheeled around, seeing that the players were lining up, preparing for another round.

Just when Aileen was about to join them, something flew in front of her face.

At first, she thought it was the golden snitch - but this tiny, flying object wasn't gold, and it certainly wasn't round. In fact, she'd seen it before.

It was a small black bat, fluttering around frantically in the freezing air.

Aileen grabbed at it, but it ascended out of her grasp.

"Valefor!" Aileen shrieked, her fingers and toes going numb, but she didn't care; she whipped around and shot after the bat, drawing her wand and flying haphazardly through the oncoming snowfall.

She forgot about the game entirely; everything around her, the snow, the crowd, the players - none of it existed. Now, the only thing that existed was the tiny bat flapping madly in front of her, flying away at top speed. Aileen soared through the air like a rocket, abandoning the field and vanishing from everyone's sight.

"Where is she going?" Samuel muttered.

"She's chasing something. It looks like a..." Professor Crowley's bewitched eye zeroed in on Aileen shortly before she vanished from eyeshot.

Then, Professor Crowley marched down the stands, staring after Aileen for a moment before looking downward, where a few of the players had abandoned their brooms, many of them gazing up at the sky in confusion.

"Accio!" Professor Crowley exclaimed, summoning one of the brooms up to the stands and catching it swiftly. He flew after Aileen in a heartbeat.

Aileen felt as if shards of glass were slicing at her face and fingers as she rocketed through the snow, the bat still barely within her eyeshot, flying away as quickly as his little wings could manage.

"Stupefy!" Aileen screamed, shooting a spell after the bat, but the bat dodged her attack. "Stupefy! STUPEFY!"

The bat bobbed and weaved through the air, jumping away from the streaks of red light.

Aileen's blood boiled, her heart hammering and her temper skyrocketing. That bat was an animagus - the same animagus who disguised himself as a pet last year, the one who turned out to be an ex-Death Eater in disguise. Valefor.

He got away before. Not again. Not this time.

"EXPELLIARMUS! STUPEFY! INCENDIO! STUPEFY!"

Aileen shot spell after spell at the creature, but none made contact.

Then, the bat dropped downward, flying toward the ground.

Aileen did the same, shooting toward the ground with no ounce of regard for her safety; the Death Eater was back, the one who tried to torture and kill her last year, the one who might've been involved with her mother's death.

She couldn't let him get away. Not again. Not again...

The bat came within an inch of the grass before changing course again.

Aileen yanked her broom upward, barely stopping herself before smashing into the ground, a wicked pain spiraling up her neck and spine, but it didn't matter. She flew after the bat again, shooting spells and flying until...

A figure came into view, and suddenly, Aileen began to slow her momentum, her mouth falling agape.

It was a person, someone lying on the ground, pale and motionless.

Aileen gasped and brought herself to an abrupt stop, stumbling off her broom and approaching the person. It was a young boy in Gryffindor robes, slowly being buried in a light blanket of snow, his skin as pale as death, his eyes open and lifeless.

Aileen felt like she might vomit, covering her mouth as tears filled her eyes. Someone died out here. A student, no less...

Her eyes darted around again, searching for Valefor, but the bat had disappeared.

Now, she was standing alone in an open field, surrounded by fog and snow. She didn't know where she was, exactly, but it must've been somewhere between the Quidditch field and the school. This boy died on his way to the game.

Aileen's hands began to shake, her stomach churning, her eyes lost in the lifeless boy. He didn't appear to be inured, but as Aileen bent down and examined him, she spotted a faint, red rash crawling up his neck.

Did the sickness finally succeed in killing someone?

"Oh God," Aileen whimpered, tears streaming down her cheeks, her anger fading into despair.

She couldn't tear her gaze from the boy's eyes, eyes wide and void of feeling, staring emptily into nothingness.

The winter air seemed to drop even lower, every breath visible, every inch of her body feeling like it might freeze solid. Aileen stared into the boy, an unbearable sense of despair sweeping over her. She wondered if her mother looked this way when she passed, eyes wide and empty, body stiff and pale... God, she could only imagine... soon, everyone would look this way... everyone would die... she'd never see Maxwell again, never get to talk to Professor Crowley, never get to hug her father... it was all over... everything...

The fog of despair felt to be consuming her, her heart aching, her mind filled with horrific images of all her friends lying dead and pale in the snow, all with red on their necks. She'd never see them again, never laugh with them again... her father would die... she would die...

Aileen sobbed over the dead boy, slowly looking up as a figure approached her. It didn't walk, but glided, coasting toward her with ease.

The dark figure loomed over her, its face cloaked, its hands skeletal and ridden with decay. Aileen stared hopelessly up at it, sniffling and choking, feeling as if every ounce of happiness had vanished from the entire world... they'd all die from the sickness, even Samuel, even Harry, even Crowley and Arius... Xyler would rule the world...

Aileen felt herself drain like a battery as the dementor siphoned her of joy, her eyes drifting shut, her breaths growing thin. The world grew colder... her body went rigid... everything was over...

"EXPECTO PATRONUM!"

Someone bellowed from behind her, and Aileen saw a blinding flash of white light. The light took the form of a bat, growing in size, and as its wings extended, a wicked forcefield exploded from the creature, sending the dementor flying.

The dementor flipped backward in the air, soaring away and vanishing into the fog as the patronus swept across the scene, driving any and all darkness away.

Professor Crowley lowered his wand as the light began to diminish. He looked down, seeing Aileen unconscious, lying beside the dead boy.

A dreadful expression took over Profesor Crowley, his mouth drifting open, a glint of shock and disbelief in his eyes as he stared at the rash on the boy's neck. Seconds after, he tore his gaze from the dead boy and kneeled beside Aileen, feeling her forehead and checking her pulse. Still warm, still alive.

"Aileen," Professor Crowley said, giving her a light shake, but Aileen didn't stir.

He heard multiple feet hitting the ground behind him, crunching the snow. Professor Arius, Harry Potter, and Samuel O'Heidin leaped off their borrowed brooms and approached the scene, all of them looking just as perturbed as Crowley.

Professor Crowley scooped Aileen out of the snow, lifting her off the ground, hoping to distance her from the infected boy. When Samuel spotted Aileen, his face drained of color.

"She'll be all right," Professor Crowley assured him. "A dementor nearly got her."

"A dementor?" Professor Arius asked, taken back. "Here?"

Harry's eyes fixated on the dead boy, his face stony and grave.

Professors Arius and Crowley followed his gaze, as did Samuel, all of them taking on the same visage of severity.

For seconds that seemed to stretch into hours, none of them spoke.

Harry took a deep breath, then faced the other three men.

"This is officially a deadly and unknown wizarding disease," Harry stated, his voice dark. "Headmaster, you'll have to make a change."

Professor Arius narrowed his eyes at Harry.

"The sickness killed someone," Professor Crowley said gravely, eyeing the rash on the boy's neck. "He's right, Zander. This sickness is capable of killing. And, now that we know... we'll have to take immediate action. Whatever this is... we can't allow it to spread."

The men fell silent for a moment. Samuel hovered in front of Professor Crowley, staring at the unconscious Aileen worriedly and swiping her bangs aside.

"All right," Professor Arius said in a dark, serious voice that didn't suit him. "Professor Crowley, please take Ms. O'Heidin to the hospital wing. After that, contact the boy's parents and tell them what's happened. Have someone come remove the body. Samuel, if you can, go back to the Quidditch field, and once the game is over, keep the students and the teachers away from this area. We don't need everyone ogling the boy before his body is moved. Harry, you'll have to contact Ross and decide what the best course of action is for the aurors now. I'm afraid this has gone too far. We need to stop this at all costs. All of Xyler's forces need to be dealt with. Now."

Professor Arius looked uncharacteristically shaken, almost furious. His hands curled into fists, his eyes switching between Aileen and the dead boy. He inhaled another heavy breath and spoke once more before the men left to do their duties as instructed.

"As of this moment, Hogwarts School of Witchcraft and Wizardly is officially under quarantine from the rest of wizarding society."