"A what?" Regulus frowned, turning to look at Alexandra.
"I-I think I know what it is," she said breathlessly, still in shock. "But it's not safe for Kreacher here. The Dark Lord can't know that he's managed to escape that cave."
Regulus hesitated at first, but finally nodded, turning toward the house elf. "Kreacher, I want you to return back home and stay hidden. Do not leave the house under any circumstances."
Kreacher nodded weakly before disappearing out of the room with a loud crack, leaving Regulus and Alexandra alone.
"What were you talking about, Alex?" Regulus questioned, looking more worried than ever before.
"It was something my grandpa had said — in his memories — but I can't remember well — there were so many more important things going on that I didn't pay too much attention to the Horcruxes — I mean, my grandpa had just died — and then I learnt that he wasn't my real grandfather — that he had killed my parents — that I was the heir of Ravenclaw — how was I supposed to know the Horcruxes were going to be important —"
"Alex, calm down!" Regulus try to say comfortingly, but he himself seemed more messed up than ever before. "What are these Horcruxes?"
"I don't remember..." Alexandra muttered, but she finally came up with an idea. "But we can watch his memory again! In the Pensieve!"
And so, before Regulus could ask her what she was doing, Alexandra opened the bedroom door and tiptoed outside, Regulus following her right behind until they entered her grandfather's old office.
There was another door inside the office, leading to a smaller room with a shelf filled with vials of silvery lights and a large pensieve in the corner of the room.
"Alex, care to explain what you're doing?" Regulus asked, confused as he watched her move toward the shelf, reading the labels on the vials.
"You'll understand in a minute," said Alexandra, taking a vial before moving back toward the Pensieve, emptying the silvery lights into it.
"Come here," she said, standing beside the Pensieve.
"What?"
"We have to put out heads in it," she explained, but that only made him more dazed.
Giving up at last, Regulus hesitantly walked toward the Pensieve and with an approving nod from Alexandra, they both lowered their heads into the basin.
Regulus yelped, feeling as though he was being sucked into nothingness, falling and falling until his feet finally gently hit the ground, though he could not feel the floor beneath his feet. When he looked up, he found himself in the Slytherin common room.
"This is my grandfather's memory," Alexandra explained, "for when he was young and a Hogwarts student."
She then pointed at a boy sitting on a couch beside the fireplace, lost in his thoughts. It was Marcellus. He obviously hadn't noticed their presence, because he was a mere memory.
Just then, Marceluus's head shot up when the door to the common room opened and a handsome and tall boy strode inside, looking stern and cold.
"That's Tom Riddle," Alexandra whispered as she and Regulus watched the boy walk in, through the memory. "He's... He's the Dark Lord."
Regulus's shock was obvious across his expression as he watched the memory in the Pensieve alongside Alexandra, his heart pounding in his chest.
"Well?" said Marcellus, looking up at Tom as he sat on the singular armchair next to the couch, his mind obviously somewhere far away. "Did you ask Slughorn about it?"
"Yes," Tom answered shortly, his cold eyes fixed on the blazing fire.
"And...?" he asked curiously, his blue eyes now on the boy, looking at him intently.
"He didn't say anything more than what I already knew," said Tom, his emotionless face unreadable and his gaze blank. "In order to do it, one must split their soul in half by committing murder, and then attach the piece of soul to another object, so it would be left unharmed."
"And can one make more than only one Horcrux?" Marcellus questioned, a glimmer of ambition in his eyes as he glanced at the boy admirably.
"He could not even bear to think about it once I asked him, but I knew it wouldn't hurt to seek for a second opinion," Tom answered distantly. "And yet... I do believe that it could be possible..."
But then, Tom suddenly turned his sharp eyes on Marcellus, as if warningly. "I'm trusting you with this important matter. One that I'm not trusting the others with. I hope you know what would happen if anybody else finds out...?"
"Your secret is safe with me, Riddle," said Marcellus, bowing his head ever so lightly. "And I'm sure you will succeed."
The handsome boy finally turned his gaze on Marcellus, his lips twitching up into a faint smirk as he said, "I always do, Blackwood. I always do."
At those words, Alexandra's and Regulus's heads shot up and they found themselves out of the Pensieve when the short memory came to an end. They both seemed breathless, shocked to their cores.
"He's... he's planning on becoming immortal..." Regulus mumbled under his breath, finding it hard to speak. "You were right... he's committed murder... he's split his soul in half... and has hidden that spare part of his soul into the locket... that's why it was so important to him. That's why he's gone to such great extent to keep it safe."
"But if someone manages to destroy it," Alexandra started, her voice hollow, "does that mean that there's still hope for ending him?"
"I-I suppose so..." Regulus nodded weakly.
Alexandra had started pacing around the room, her head starting to ache with all the thoughts that were attacking her mind all at the same time, as she thought of all the things that Lord Voldemort had done.
Her parents were dead because of him, and so was her grandfather. He had captured Edna, and had turned Alexandra herself into one of his Death Eaters. But she then thought of all the families he had ruined, all the Muggles he had tortured, all the innocent people he had murdered...
If nobody stopped him, then this would go on and only get worse and worse by each passing day. He would continue to kill and torture until all that was left would be power-hungry wizards as he ruled over Muggles, beginning an even bigger war.
"We have to tell Dumbledore," said Alexandra, still walking around the room, lost in her pondering mind.
"Are you mad!?" Regulus frowned. "We're Death Eaters, Alex! Do you think he's going to believe us!?"
"Then what are we supposed to do about this!?"
"Nothing!"
"But —"
"Alex, please be reasonable," he said, trying to speak more gently, "this is the darkest wizard of all time we're talking about. If not even Dumbledore could stop him, what do expect we can do!?"
"I don't know! But we can't just sit around and do as he orders!" Alexandra retorted. "Regulus... I can't stand the thought of hurting anyone. I just can't. And I won't stand it if he wants to hurt anyone else either."
"Alex —"
"What if the next victim was someone you cared for?" she cut him off briskly, though still trying to speak quietly. "What if it was Sirius, your brother? He was very well capable of letting Kreacher die in that cave for no reason. He's not going to care about us either! He's not going to stop... ever. And 'ever' is a very long time when it comes to someone who's looking for immortality."
Regulus remained silent, watching her warily as she went on, breathing rapidly.
"He must be stopped, and I don't care at what cost," she said. "And we might not be powerful enough to stop him, but we know his secret. We can help and end this, no matter what the cost."
Regulus hesitated. "He will kill us if he finds out, which he will eventually."
"I don't expect you to come along with me, Reggie," said Alexandra, offering him a little smile. "But I'd rather die as someone who fought for the good side, rather than to live and survive in the dark side."
"What are you planning on doing, then!?" Regulus asked, feeling the panic surge from within him.
"I don't know," she muttered, pursing her lips together thoughtfully. "I'll — I'll have to get the locket and try to destroy it, so he would become mortal once again. And if — if I survived after succeeding, I'll just change my name and runaway to a Muggle town and live happily ever after with Edna," she said the last part jokingly, making Regulus chuckle.
But his laughter soon faded away as she watched her closely. "You're right..."
"What?" Alexandra's head snapped up at those words.
"I said you're right," he repeated himself. "I can't stand to see him hurt anyone I care for. We might not be a match to him... but we can help to give an end to this madness."
"If you don't want to —"
"I do," Regulus said firmly, walking forward to hold her hands in his, bringing them up to place a soft kiss on her knuckle. "I won't leave you alone."
Alexandra was quiet at first, pondering the matter, until she finally said, "Well, then... I might have a plan."