Chapter Text
February
“You went back to that house! Alone! What if it had gotten to you?!”
“You stole from a thirteen-year-old! You broke into their dorm! And what do you mean?! You spoke to Hagrid?! Leave the poor guy alone!”
The first day after Reg was back… well, let’s just say, it involved a lot of screaming, shouting, and wildly gesticulating (with one hand) to a lonesome invisibility cloak lying discarded on the bed. Peter was quite glad that his mother couldn’t hear their pathetic display.
Before dinner, they managed to agree to:
- not steal from teenagers without the agreement of the other,
- not touch anything Horcrux-related without the other’s permission,
- and not traumatize Hagrid anymore just because they were in a bad mood.
This agreement would have probably been more satisfying if either of them had been even remotely remorseful for their actions.
Still, Regulus seemed relieved when Peter told him they wouldn’t be doing any solo adventures for the foreseeable future.
Which was the only reason Reg got to eat the chocolate muffins Peter had baked as an apology for setting Riddle’s house on fire. Not that he felt like he had to apologize after the kind of bullshit Reg himself had gotten up to.
February was spent quietly in a truce. Regulus took over researching ways to kill Horcruxes, reading up on both dark and light medicine, and playing the violin.
Peter had a moment of panic when he realized that he would have to learn how to walk as a rat with only three paws. Which resulted in spending a lot of time falling around as a rat. He also tried his hand (ha) at more wandless charms, ingraining them into his brain in the hopes of them making up for him still forgetting that he missed a limb.
Through it all, Regulus tried to teach Peter a few healing charms to lackluster results, while Peter taught Regulus the Fiendfyre curse that he had unleashed onto the building, with much more promising results. Peter’s Patronus charm produced a slight silver wisp with the memories of his mother and Regulus sitting with him on the sofa watching Christmas movies. The slight wisp wouldn’t be enough to stop a Dementor, but it was enough progress for Peter to feel safer when they decided to regularly visit Hogwarts in search of the Chamber of Secrets starting in March.
March
Despite their intentions of leaving the recklessness and stealing behind them with spooked schoolchildren and burning houses, they were soon reminded that in the end, they only ever encouraged each other’s best and worst attributes.
“I don’t see the point of this,” Regulus sighed, watching Peter sitting in a quiet corner of Hogwarts, engrossed in his task.
“The point,” Peter started, not looking up, “is not getting eaten when I transform.”
He fed the huge orange cat a few treats, who looked up at him with something like disdain and mistrust. Carefully, he patted her head, which got him the biggest side-eye he had ever seen on a cat. It was progress though—after all, the first few times he got scratched and bitten for the offense of trying to look at her.
Regulus just scoffed, rolled his eyes, and started reading the book he had stolen from a NEWT student. Peter had strongly disapproved, but Regulus seemed to believe the poor Ravenclaw was deserving of Madam Pince’s ire and took his sweet time reading up on seventh-year Charms lessons. Peter, who had hated Charms almost as much as Transfiguration, was absolutely baffled that one would study for that after already achieving an O in their NEWT (and being both a wanted criminal and a lord with more money than reasonable, who clearly had no need nor prospect of ever having a normal job).
But who was Peter to judge? After all, he was currently on a mission to befriend all the Hogwarts cats that had tried to eat him when running around as a poor, three-legged, slow little rat.
“Okay, let’s try this again, dear,” mumbled Peter to the cat. He carefully settled down a few feet away from the cat and took a deep breath.
Then he transformed.
The cat stared at him.
He stared at the cat.
Then the cat leapt forward, while Peter shrieked and sprinted around the corner.
Regulus let out a deep sigh and left the two to whatever they were trying to achieve. He turned back to the book on healing charms and continued reading.
April
March turned to April. Regulus stole more books. Peter still got chased by cats. They visited Peter’s mom and Kreacher, visited Hogsmeade in Polyjuice Potion, read newspaper articles about themselves, visited about every room in Hogwarts they could find, and had a few close calls with the Weasley twins and the ‘golden trio’.
One night, they found themselves sitting on the roof of the Astronomy Tower, looking out onto the Black Lake and the forest. They had bought Butterbeer and pastries in Hogsmeade, and Regulus spelled them to not fall off the roof while they ate and watched the Dementors hovering in the distance.
Sweet Butterbeer still on his tongue, Regulus spoke: “Do you think they at least try to teach the kids how to repel those things?”
Peter had wondered about that too. Writing OWLs and NEWTs with Dementors hovering around the castle grounds couldn’t be a pleasant experience. Especially since the creatures seemed to get bolder and closer with every month.
“Probably not,” muttered Peter. “They are notoriously bad at responding to shit like this, if the chamber business and our school years are anything to go off.”
Regulus hummed in agreement and took a bite of his pumpkin pasty.
“Maybe they teach the older students the Patronus charm,” conceded Peter. Remus probably would at least try to teach the kids prone to sneaking out the spell.
“I’m sure the house-elves are putting chocolate in every other dish,” added Regulus.
Quiet fell over them. Sunken in deep thought.
“Do you think if we’d attack the Ministry, they’d station the Dementors there?”
“Why would we attack the Ministry?”
“I still have a few people on my list.”
Regulus threw him a glance.
“The list where you stuff people’s mouths with newspaper and leave them to the Dementors?”
“The very same.”
“I’d rather keep the murder to a minimum, Peter.”
“Ah, so stealing from kids is alright, but a little murder is bad, Lord Righteous?”
“Oh wow, you actually got it!”
May
The cats finally seemed to relax around Peter, who was just a little bit smug about that.
Well, most cats. But he never had much hope for Mrs. Norris and that one fluffy ginger cat either way.
They turned around every stone in Hogwarts. To get around more easily, they even Polyjuiced into some of the busier Prefects to check the pictures and hallways for any sign of soul magic (that weren’t the Hogwarts wards, but Peter tried hard not to think about that).
The twins and the one female friend of baby Potter were about everywhere, which got Regulus a calculating look in his eyes. Probably suspecting one of them to be in possession of the map. However, Peter made sure that his friend knew that he could and would drown him in the lake if he tried to steal from another thirteen-year-old. The glint didn’t really vanish until they saw the girl fumble with a shiny necklace. After that, it was mostly incoherent muttering of incompetence from the Ministry and Hogwarts teachers. Peter didn’t ask for an explanation. He really was happy with his disillusionment with both institutions. A shiny necklace couldn’t be worth his own questionable sanity.
On the last weekend of May, they sat together in Hogsmeade, near the Shrieking Shack.
“I am Voldemort and want to hide a piece of my soul in Hogwarts. Where do I put it?” Regulus mumbled for what must have been the hundredth time in the past few months.
“Somewhere no one would expect. Like the toilet by the Headmaster’s office,” answered Peter, not looking up from where he was playing with a small grey cat that liked bumping her head against his handless arm.
“We already looked there.”
“In plain sight, like one of the stone statues in the Great Hall.”
“We checked those too. No sign of dark magic.”
“Somewhere with so much stuff, it’d take ages to find anything. Like the library.”
“We checked that too. There wasn—” Regulus trailed off.
Peter looked up to see Regulus scrunching his face, staring into the middle distance.
Patiently, Peter waited for him to speak, softly stroking the fur of the little cat curled in his lap.
“Did I ever tell you I used to be sort of friends with Severus?” Regulus asked.
He had alluded to it before—mentioned potion tutoring and their shared contempt for the Marauders. Later, they'd joined the Death Eaters together. Regulus had seen Snape slip pain-relief potions into prisoners’ water, sometimes even leaving the chains unlocked. Neither of them ever mentioned those small rebellions aloud.
Peter had assumed it was more of an alliance between two people stuck in the same death cult. But then again, that was a pretty solid foundation for a friendship.
“In his last year at Hogwarts, he got a little paranoid,” Regulus began, causing Peter to wince. He might have played the smallest role in Sirius’s murder attempt, but he had no illusions—he wouldn’t have spoken up even if he’d known.
Regulus didn’t notice Peter’s reaction and continued. “When we studied, he stopped using the library. And when the Death Eaters got worse and our common room more dangerous, we looked for a place to study in peace.”
“What did you find?”
“A room where you can hide yourself.”
June
You couldn’t just hide yourself in the room.
Apparently, you could also hide mountains of things.
“…This will take a while,” Peter mumbled.
“…If we haven’t found the Horcrux by the end of the month, we move to Italy for a year and do anything but this, okay?”
“I think we should do that either way.”
As far as the eye could see: mountains of hidden things. Pictures, furniture, books, forbidden objects, expired potion ingredients, skeletons of forgotten animals, knives, kettles, brooms, scrolls, love letters, vials of unidentifiable substances—and so, so many dark illegal artifacts.
Students must have held entire rituals in this room. Considering how many darker traditions had been outlawed even before Grindelwald, that wasn’t surprising. The old families wouldn’t have stopped practicing their religion without a fight. And neither would their children.
The marks must have been old, though—even Regulus seemed to lack knowledge of how they were performed.
With a lot of cursing, they sorted through the mess. Spell after spell, they tried to locate the most potent dark object in the room. But it seemed dark illegal artifacts were the number one thing students liked to discard.
Days passed. The room provided food, and there were plenty of places to sleep among the rubble. A few cleaning spells from Regulus, and they were good to go.
Peter lost an entire day collecting books that should have been burned two hundred years ago.
Regulus stopped searching to investigate a mysterious cabinet that could apparently transport people—if fixed. That led Peter to promise to take him to a Muggle library for a copy of Narnia.
Time slipped through their fingers for a week.
They didn’t find anything.
Until something found them.
Peter had started the day reading about how to create Inferi. It was complicated and horrifying and made him more grateful than ever that Voldemort had fished Regulus out of the water instead of letting him drown.
Creating Inferi was a moral nightmare—damning creatures to a half-life, keeping the body alive and the soul bound while letting the mind rot inside a decaying vessel.
It fascinated Peter to the point where he questioned the wisdom of reading the book instead of burning it. He had no ambitions of ever creating an Inferius, of course. But once, he’d had no ambition to kill someone by shoving newspaper down their throat. Once, he had no ambition to choose the greater good over the people who mattered. Once, he never thought himself capable of killing anyone.
Things changed.
He had proven himself wrong time and time again, and the book felt cold in his hands. Every piece of dark knowledge in his brain was at risk of becoming not gruesome enough to deter him. He had known that at the very latest after bleeding out Death Eaters who had tried to kill his mother.
He was not a good person.
Maybe knowledge on how to bind souls into half-lives shouldn't be swirling around his head forever.
He closed the book and put it into his bag with the others he’d collected.
“We could try designing a ritual ourselves,” Regulus said suddenly from his own pile of books. “If we combine what you already know from working on the map, with some of these…”
“We’d get ourselves killed,” Peter interrupted. Soul magic wasn’t something you messed with—as the Hogwarts wards had thoroughly proven when he was a teenager trying to figure them out. Using rituals and poking at the wards was one thing. Combining two or more rituals for a new purpose? No way.
“We need a different approach, Pete,” came the exhausted reply.
They were both tired.
Tired of shifting through cursed junk.
Tired of finding things far more dangerous than anything that should’ve been in a school.
The weight of the endless room pressed in on them a little more every day.
“We don’t even know if he hid it here. What if we’re just wasting time? What if he’s getting stronger while we’re running around headless, chasing something we can’t prove?”
Peter shook his head. “It won’t help if we kill ourselves trying to play with magic we can’t control, Reg.” He sighed, rubbing his eyes.
Softly, Regulus murmured, “Maybe it’s time to get help.”
Peter grimaced. “Like who?”
They both knew their options weren’t great—or many.
“Who would still listen to us?” Regulus said, pacing in circles. “Would Sirius and Remus believe us? Dumbledore? Who’s even left? Snape? Andromeda Black?”
Who was still alive, that they could trust?
“Maybe I can help you,” a raspy, feminine voice spoke up.
In an instant, both turned around, wands raised, scanning for the speaker.
A woman stepped out from behind a pile of junk, her gown long and flowing, adorned with intricate patterns of moons and stars. She was grey and translucent—an old Hogwarts ghost.
“The Grey Lady,” whispered Regulus, lowering his wand, eyes wide with wonder.
Peter, slower on the uptake, held his wand ready. He didn’t know who she was.
“Regulus Black,” the ghost said. Her face was blank and her voice cold, but Peter thought he saw something like affection in her lifeless eyes. “We haven’t met in a long time.”
Regulus bowed.
Peter mimicked him.
“It’s an honor to see you again,” Regulus said.
The Lady was unmoved by his reverence. She merely hummed.
“You are searching for something that used to belong to my mother,” she said. “What do you intend to do with it?”
“Destroy it,” Regulus answered, holding her gaze. “We need to destroy it—and anything like it.”
The Lady studied him for a long moment, then nodded.
“It does not want to be found—not by anyone but its own soul. But the object around it was my mother’s. And after that, mine. I can lead you to it.”
Regulus followed her, Peter close behind, wand ready.
“The ghost of Ravenclaw,” Regulus murmured. “She used to hover around Pandora, back in Ravenclaw Tower.”
They stopped in front of a small cabinet Peter realized he’d walked past countless times.
What day was it even?
“I once trusted a young man, not unlike you, with the knowledge of where it was,” the Lady said. “I have regretted it ever since. Don’t make me regret this too, little Black.”
She stepped aside.
Inside was a diadem.
The diadem. A bird emblem, sparkling sapphires, and dark magic clinging to its edges.
It looked… familiar.
Peter glanced at the ghost, comparing her to the statue of Rowena Ravenclaw. There were faint similarities—the dress, the sharp jaw, the Grecian nose. But while the founder was depicted as regal and composed, this woman looked haunted, bitter.
She caught him staring, her eyes sharp.
“If he falls to the lure of the diadem, you must kill them both,” she said. It wasn’t a plea or a warning—it was an order.
Peter blinked. “Sorry, but I’d rather watch this castle burn than do that.”
She didn’t look surprised or disappointed. Just cold.
Regulus looked over at him, unreadable. Peter shrugged and gave a half-smile.
“It’s promising me knowledge and wisdom,” Regulus muttered.
“Don’t put it on. Your head’s too pretty to end up like my hand,” Peter quipped, startling Regulus out of whatever spiral he was in.
With a huff of laughter, Regulus raised his wand. “Fiendfyre.”
The world exploded into light.
The diadem screamed.
Peter backed up, wand raised, ready to drag Regulus out if the flames got out of hand.
But, anticlimactically, the fire died. Regulus stood over a pile of ashes, breathing hard.
“Is it dead?” Peter asked, to no one in particular.
The ghost gave a rough chuckle.
Regulus and Peter turned to her. Her face was streaked with spectral tears, a smile on her lips.
“Thank you,” she whispered—and vanished.
Peter groaned, dragging a hand down his face.
“What a creepy-ass bitch.”
Peter stepped carefully to Regulus and slipped an arm around him, steadying him.
“I can’t believe that worked,” he said.
“Me neither,” Regulus whispered, still staring at the ashes. “Part of me wishes the diadem had survived.”
He sounded scared. Peter pressed a little closer.
“I’ll destroy the next Horcrux, okay?”
Regulus nodded, trembling. “You could do it right now, you know?”
Peter thought of the ring in his pocket. But he shook his head. Regulus was close to collapsing. And Peter wasn’t sure he’d handle destroying a Horcrux any better.
“We know fiendfyre works. There’s no rush. Let’s get out of here first.”
He checked his phone.
“It’s the ninth,” he said.
“It’s a full moon tonight,” Regulus noted.
Peter hummed. “Then let’s get out of here now.”