"Dad, seriously, you've been saying this since morning like a broken record," Cassiopeia groaned, rolling her eyes.

"It's not a joke, Cassie. You can't go searching for Sirius," Regulus replied, exasperated.

"But what if we accidentally cross paths? Can I curse him at least... pretty please?" Cassie pleaded, her grey eyes sparkling.

"No, Cassie. He's a murderer. Promise me you'll use the bracelet I gave you if you see him. Tap it twice, and I'll come right away."

Cassie nodded, disappointed, though secretly doubting she'd ever need to use it. There was no way she'd let her father risk his life.

Regulus couldn't help but shake his head at Cassie's disappointed expression on not being able to risk her life; she reminded him so much of Sirius at times.

"Come on, Cassie. Look on the bright side. You have the new Dark Arts book I gave you for Christmas," he said, trying to lift her spirits.

Cassie's face immediately lit up. She had always had a knack for dark magic and wandless spells, though she had only mastered disarming wandlessly so far.

"Okay, listen," Regulus said, placing his hands on her shoulders and meeting her gray gaze. "Promise me you'll stay safe. Please."

"Of course, Dad. Me and trouble? Never," Cassie replied with a smirk.

"Yes, of course... my little star," Regulus said, pulling her into a hug.

"Kreacher!"

The old house-elf appeared, wearing a crooked smile.

"Apparate her to the station. The Malfoys must be waiting."

"Right away, Master," Kreacher replied, beckoning for Cassie to follow.

"Okay," Cassie said, grabbing her trunk and giving her dad one last smile.

"Bye, Dad."

Regulus stood in the doorway, a heavy feeling settling in his chest as he listened to the crack of apparition echoing through the empty house. It was a sound he had grown accustomed to over the years, yet this time, it filled him with a sense of foreboding.

It was a nagging sensation that had been gnawing at him for days, growing stronger as the time for Cassie's departure drew nearer.

He couldn't help but feel something is gonna go wrong this year.

**********************************************************

Cassiopeia Black

She was formidable, with her black curly hair... and the rumored Black family madness surrounding her. It was no wonder Theo hadn't approached her first.

He, Draco, and Blaise had been roommates, just as Cassie, Pansy, and Daphne were. Cassie was reserved, rarely speaking to anyone except Draco, her cousin. The rest of them were greeted with nods or small waves if Cassie was feeling particularly benevolent.

But Pansy was persistent. She wore Cassie down until they became friends.

And as for Theo and Blaise, let's say they managed to get into a brawl with the seniors in their second year... and were... uhm... definitely not on the winning side.

Cassiopeia happened to saunter by at just the right moment... sensing the situation, she immediately stepped up.

"Is there a problem here?" Her grey eyes giving the renowned Black death stare.

The seniors looked like they were gonna piss their pants out of fear. They immediately opened their mouth perhaps for a curse... they never got to know, as the second later they were hurled across the hall by a powerful spell from Cassie.

The girl honestly got fuckin scarier day by day... she turned back with a soft murmur of concern. "Are you okay?"

He and Blaise, still terrified, nodded dumbly.

"I don't bite, you know," she smirked.

She chuckled at the scared expression on our faces. "You seem okay. Friends?" she offered.

And well, that was it.

Being friends with the rumored psycho girl had its perks. No one dared to cross them. Everyone was too scared to mess with us in the fear of pissing off Cassiopeia Black. Everyone except that stupid fuckin boy who lived and his little gang.

**************************************

At Platform 9¾, Draco Malfoy's impatience was at an all-time high as he craned his neck for what felt like the hundredth time, scanning the bustling crowd for Cassiopeia.

"Did you spot her, Theo?" he asked, his frustration evident.

"For the tenth time, Draco, no. She'll show up, just give it a minute," Theo replied, exasperated, his eyes darting around in search of their friend.

"Draco! Stop jumping around. Stand properly. You look like a fool," Mr. Malfoy's sharp voice snapped Theo's train of thoughts. Draco shuffled and straightened his back in what was called the perfect pureblood posture. "Yes, Father," he murmured, his face down with embarrassment. A very familiar curt voice came in reply.

"Are you sure you weren't looking at the mirror, Uncle?"

"Cassie!" Draco's voice immediately brightened as he looked up. Mr. Malfoy silenced him with a look.

"Well... looks like you still haven't changed, Cassiopeia," Lucius sneered.

"Nor did you, Uncle... And here I thought you might have softened in your old age," her voice swift in reply, sneering right back.

Sensing the escalating tension, Narcissa stepped in, her voice calm but firm.

"That's enough, Cassie, Draco, Theodore. Let's get on the train, all of you. We don't want to be late."

Without further ado, Draco and Theo hastened onto the train... looking for the compartment with Blaise and Pansy.

Meanwhile, Cassiopeia lingered, her gaze still laced with animosity.

"Perhaps it's time you learn to treat Draco with more kindness, Uncle," she remarked coolly before striding away and boarding the train.

As Cassiopeia walked away, Lucius Malfoy's glare bore into her back, dripping with venomous resentment. 

**********************************

"I hate your dad," Cassie announced.

Cassie settled into the carriage beside Theo and Pansy, her announcement hanging in the air like a heavy cloud.

"Cassie!" Pansy squealed, immediately wrapping her arms around her in a tight hug.

Cassie patted her awkwardly, "Let me go before I curse your hair red."

Pansy squealed again and quickly backed off, leaving Cassie to settle in. Theo chimed in agreement, "I agree with Cassie on this one, Draco. Your dad is acting like an ass."

"What happened?" Blaise asked, opening a packet of sweets.

"My uncle dearest is being a complete asshole, Draco. I'm sorry, my cousin, but you need to grow a fucking spine and stand up to that pathetic excuse for a father," Cassie said.

Draco's retort was swift, his voice rising, "Enough, guys. He just wants what's best for me, and no more discussion about him."

Cassie sensed Draco's discomfort and motioned for everyone to stop. The others caught on quickly and nodded in agreement.

"Anything from the trolley, dears?" came the voice of the trolley witch from afar.

"I'll go get something," Draco immediately stood up, walking out of the compartment.

"Cassie, why don't you follow him? You understand him better than anyone else does," Theo offered, earning a nod of thanks from Cassie as she went off in search of Draco.

Draco was seated alone in an empty compartment, his head bowed. "Dray?" Cassie's voice broke the silence softly.

"I'm fine, Cassie. Leave me alone," Draco replied curtly.

"Is that an order?" Cassie's voice took on a mockingly angry tone.

Draco gulped nervously, not wanting to upset her further, "No." He stood up.

"Listen," Cassie began, her tone softening, but Draco interrupted before that.

"I know, I know you all are right, but I can't... he's my father, Cassie."

"He is still an asshole but, fine," Cassie remarked.

"Let's go, Dray. They're waiting. They think we're searching for snacks."

Draco shrugged, his face stoic as they walked together toward the trolley.

"Anything from the trolley, dears?" the trolley witch asked sweetly.

"15 chocolate frogs and 5 pumpkin pastries," Cassie ordered, her gaze shifting toward a nearby compartment where she could hear the voices of Potter and his friends. She nudged Draco slightly, gesturing toward the compartment.

Draco quickly paid the sickles, and they both walked toward the compartment. As Draco dramatically opened the door, Cassie leaned against the doorframe, her smirk forming.

"Well, look who it is," said Malfoy, his usual lazy drawl in place, as he pulled open the compartment door. "Potty and the Weasel."

Cassie chuckled, her eyes glinting darkly. "I heard your father finally got his hands on some gold this summer, Weasley," Malfoy continued. "Did your mother die of shock?"

"Never seen that much gold, have you, Weasley?" Cassie added, her tone dripping with sarcasm.

Ron stood up so quickly he knocked Crookshanks's basket to the floor. Professor Lupin gave a snort. "Who's that?" said Malfoy, taking an automatic step backward as he spotted Lupin.

"New teacher," said Harry, who got to his feet, too, in case he needed to hold Ron back. "What were you saying, Malfoy, Black?"

Malfoy's face dropped slightly, gesturing for Cassie to leave, but she wasn't having it.

"Looks like being the Boy Who Lived finally took a toll on you, Potter. Going hard of hearing or just wanted to hear Ron's insult again?"

Harry's face contorted in rage as he immediately reached for his wand. Draco and Cassie responded in kind.

"You can't beat me in a fight, Potter. You and I both know it." Cassie sneered

Hermione watched the exchange nervously. "Guys, let's not fight with Professor Lupin in the compartment. You'll all get in trouble."

The name struck a chord in Cassie's head. "Lupin? What's he doing here?"

She remembered him from Regulus's stories about her father. Lupin, the werewolf.

"Let's go, Cassie. It's not worth it," Draco mumbled.

"Yeah, Cassie," Ron said, mocking Draco. "Listen to Baby Malfoy here."

Cassie snapped. No one mocks Cassie's friends in front of her. "You fucking blood traitor!" she spat before wielding her wand casting a darker curse "Ulcus Apparabate!"

Draco's eyes widened in recognition of the dark curse, but luckily, Ron dodged it, shattering the Sneakoscope behind him in the process.

The impact caused Lupin to wake up with a jerk, his hand instinctively reaching for his wand.

But there was no time to think as the train slowed down, eventually coming to a stop with a jolt.

The train was plunged into total darkness, and distant thuds and bangs indicated that luggage had fallen out of the racks. Then, without warning, all the lamps went out and they were plunged into total darkness.

"What's going on?" said Ron's voice from behind Harry.

Harry felt his way back to his seat. "D'you think we've broken down?"

Draco's murmur was barely audible as he moved behind Cassie, seeking refuge in the darkness.

"There's something out there," Ron's voice cut through the tension, his tone urgent. "I think people are coming aboard..."

"Ouch!" Hermione's gasp of pain broke the silence. "Ron, that was my foot!"

"Shut up, all of you. Something's coming," Cassie interjected sharply, her voice slicing through the confusion.

"Hermione?"

"What are you doing?"

"I was looking for Ron--"

"Come in and sit down--"

"Not here!" Harry's hurried interruption echoed through the compartment. "I'm here!"

"Ouch!"

"QUIET!" Cassie's sharp command blended seamlessly with a hoarse voice from the shadows.

"Lumos Maxima!" Cassie waved her wand, illuminating the compartment with light. Professor Lupin held a handful of flames, his tired face now visible in the flickering light, his eyes alert and wary.

"Stay where you are," Lupin instructed in his hoarse voice, slowly rising to his feet with flames held out in front of him. But before he could reach the door, it slid open slowly.

Standing in the doorway, illuminated by the flickering flames, was a cloaked figure towering to the ceiling, its face hidden beneath its hood.

Draco and Cassie, closest to the door, immediately backed away, a sense of dread washing over them. Draco shuddered, sinking down slightly, his usually pale face even paler.

Cassie sensed the presence of Dementors and instinctively positioned herself protectively in front of Draco. She knew the Patronus charm; Regulus had taught her.

She could hear Lupin say something, but she didn't focus. She needed a happy memory. Her 7th Christmas with Regulus. It was a wonderful memory, but was it happy enough? Focusing on it, she chanted, "Expecto Patronum!" A bright white light emerged from her wand, acting as a barrier.

Lupin too cast the charm, conjuring a silver wolf that charged at the Dementors, causing them to flee.

As the tension eased, Cassie felt Draco slowly regain his strength, weakly standing up and trying to appear unaffected.

"Harry! Harry! Are you all right?" Hermione and Ron hovered over Potter, who had fainted.

Harry's eyes fluttered open, the lanterns above him casting a dim glow. "Are you okay?" Ron asked anxiously.

"Yeah," Harry replied, glancing toward the door where the hooded figure had vanished. "What happened? Where's that... thing? Who screamed?"

Cassie frowned. Screamed? What was this Potter playing at?

A loud snap made them all jump. Professor Lupin was breaking an enormous slab of chocolate into pieces. "Here," he said to Harry, handing him a particularly large piece. "Eat it. It'll help." Harry took the chocolate but didn't eat it.

"What was that thing?" he asked Lupin.

"A Dementor," Lupin answered, offering chocolate to Cassie.

"No, thank you." Cassie recoiled, her mistrust evident.

"I haven't poisoned that chocolate, you know, miss--" Lupin began,

but Cassie cut him off with a smirk. "Black."

Lupin's face fell in disbelief, unable to process the revelation.

"That's right. Cassiopeia Black," she declared, turning to Draco. "Let's go, Dray."

"See you later, Professor Lupinotuum (Wolf in Latin)," Cassie said, smirking as Lupin's face grew paler as he understood what she revealed.

Lupin's mind raced in disbelief as Cassie and Draco exited the compartment. Sirius never mentioned having a daughter. He never told us about her. How could he have kept such a secret?

Note-- Some dialogues are taken directly from J.K. Rowling's book harry potter and the Prisoner Of Azkaban