Hogwarts was filled with gossip. Echoes of whispers and murmurs and excited squeals reverberated around the stone-floored and stone-walled corridors, reaching even the high rafters where Regulus liked to sit and observe from time to time. He ought to have realised that the castle's rumour mill wouldn't have died along with Evan Rosier, the main instigator of gossip during Regulus's own schooldays, but it was a rather nasty surprise to suddenly have the name Potter on everyone's lips once more.

Granted, Harry didn't appear to particularly enjoy being the centre of attention as much as his father had, but that fact did little to ease the twisting, sickening feeling Regulus experienced every time he heard the boy's surname.

Draco was the only other occupant of the castle that seemed to dislike the name Potter as much as Regulus did.

He had been almost continuously bad-mouthing Harry to anyone that would listen, repeating the story of their exchange on the Hogwarts Express over and over until even shy little Tracey Davis, the sole muggle-born student in that year's Slytherin cohort, had yelled at him to put a sock in it.

This had, predictably, enraged Draco. But he had since changed tact, attempting instead to persuade the student body that he was far more worthy of being talked about than the Boy-Who-Lived. He boasted about his family and his wealth and his perceived intelligence in increasingly desperate attempts to draw attention away from Harry and back towards himself. He stuck his chin in the air and looked down his nose at everyone with a haughty, arrogant look that reminded Regulus, distressingly, of himself as an eleven-year-old.

Draco's posturing worked on some of his classmates. The two large boys, Vincent and Gregory, were very loyal to him - or perhaps just too stupid to form their own opinions. Regulus had heard from Violet, the most gossipy portrait in all of Hogwarts, that Gregory had spent the duration of his first Astronomy class peering through the wrong end of his telescope. Whether out of loyalty or stupidity, both boys could usually be found standing sentry on either side of Draco like bodyguards.

Two of the first-year girls, Pansy and Eloise, seemed utterly enamoured by Draco. They were happy to sit and listen to Draco all evening long as he draped himself languidly over a green armchair and held court among his classmates.

Theodore mostly kept his distance from Draco, choosing instead to strike up a tentative friendship with the blonde girl, Daphne, and a couple of second-years that Regulus occasionally accompanied to the debate team meetings. Unfortunately, Theodore still hurried to Draco's side whenever he was summoned; Regulus suspected it had something to do with their fathers' business relationship rather than any genuine friendship.

"There he is!" said a voice in an excited squeal.

Regulus leaned forward from his perch on the ceiling beam, peering through his knees at the top of the children's heads below.

"Where?"

"Next to that ginger kid!"

"With the glasses?"

"Yeah! Oi, POTTER!"

Regulus gave a heavy sigh, wishing the act was as effective as it had been when he'd been alive and could actually exhale breath, and floated up through the ceiling to the next floor where he could hopefully escape the memory of his nemesis for just one day.

He was drifting down corridor after corridor, not paying much heed to where he was going, trying not to think about how much he hated James bloody Potter, when a pair of first-years unexpectedly opened a door he had been about to pass through.

"Oh, I'm so sorry," Regulus said quickly - he could well remember that horrible cold, damp feeling a warm-blooded living body experienced when a ghost glided through them - and withdrew.

"S'alright," the taller boy muttered as he inched past Regulus, trying not to pass through him again.

But Regulus was frozen in place. Because the shorter boy had James Potter's nose and James Potter's chin and James Potter's ridiculous bloody hair .

Harry's hand flew up to his forehead, self-consciously trying to flatten his disturbingly messy hair and conceal his scar. Regulus realised he had been staring and glanced away.

"Excuse me," he said quietly, and sank back down through the floor.

Regulus found himself passing through the ceiling of Professor Flitwick's classroom and took a seat at an empty table near the back of the room.

In the traumatic weeks immediately after his death, Regulus had often sat in on various lessons, finding a sense of normalcy in drifting among the faces he could recognise, no matter how horrified they often were to see him.

But as his old schoolmates grew and matured and eventually moved on from Hogwarts, leaving Regulus behind, the lessons took on a new meaning to him. He went to classes he had never dared attend while he had been living - Muggle Studies, of course, but also Care of Magical Creatures - and made sure to keep paying attention in other lessons so he could help the younger students with their essays whenever they needed him.

A few minutes after he had arrived, the Charms classroom door flew open with a bang and Harry Potter and the Weasley came rushing in, apologising for their tardiness though Flitwick didn't seem to mind. Regulus felt himself tensing and almost left the classroom again but forced himself to stay, and observe; to see for himself whether Harry had inherited as much of his father's personality as he had his appearance.

Not much, it seemed. Regulus had never had the displeasure of sharing a classroom with James Potter, but he imagined he would have been as irritating a classmate as he was everything else: leaning back in his chair, as Sirius had always done, trying to catch girls' attention, tossing notes across the classroom, constantly chatting to his friends, making a general nuisance of himself.

But Harry did none of those things. Despite his tardy arrival he set quickly to work, sitting quietly beside the Weasley and taking diligent notes. He ignored the whispers and stares from his classmates and kept focused on Professor Flitwick's lecture, his quill moving swiftly across his parchment.

And as the class came to an end, Harry packed away his belongings and left his desk just as tidy as he had found it, moving along to his next class with the rest of the Gryffindor and Ravenclaw first-years.

Regulus drifted towards the front of the class and greeted his old Charms professor.

"Ah, Regulus," said Professor Flitwick with a smile.

"The new first-years are an interesting bunch," Regulus said. "Everyone is talking about Harry Potter, of course…"

"Yes, indeed! I had hoped he might be sorted into Ravenclaw, but with parents like Lily and James I don't suppose there was any question that he'd be placed somewhere other than Gryffindor!"

"Yes, of course…"

Professor Flitwick had nothing but fond memories of James. The same was true of Sir Nicholas - "Oh, the larks he would get up to with those companions of his - and such a handsome fellow!" - and the other ghosts were quite disinterested. The Friar suggested that he ask Peeves, since James and Sirius and the others had often been in cahoots with the poltergeist, but Regulus didn't think he was quite that desperate yet.

He drifted back to the Slytherin common room and sat in his usual seat beside the lake, wondering whether his memories of James had twisted into something rather more terrible than they actually had been in life.

He stayed there for hours as students came to and from their classes and eventually began to settle around the common room after they had finished eating their dinners in the Great Hall.

Regulus was still musing about James when a familiar haughty voice cut through his thoughts.

"My father has always said that goblins can't be trusted."

He glanced across the room in the direction of the voice and saw Draco holding court in his usual armchair, holding a copy of the Daily Prophet in one hand while he gesticulated with the other.

" We keep all our heirlooms and such things in the Manor, of course. It's far more secure. Father says that goblins sulk in their caves waiting for the day when they can get their grubby hands on our treasures. I pity those who cannot afford to secure their own homes," he said, casting a scornful glance at Eloise Midgen. The girl looked away, her cheeks flushing pink.

Regulus frowned. Either Lucius Malfoy had drastically changed his opinion on Gringotts, or Draco was bluffing. He recalled Lucius being particularly smug after completing the marriage negotiations with Narcissa's parents, boasting to anyone who would listen that his bride would come with an ancient, dragon-guarded vault deep within the underground tunnels of Gringotts.

Unless Lucius had in his possession something so valuable that he didn't dare entrust it to the goblins. Regulus narrowed his eyes, mulling over this thought.

"What do you think the thieves were after, Draco?" asked Pansy.

"Gold, I expect," Draco said dismissively.

"I doubt anyone who had the ability to break into Gringotts would do so just for a bit of gold," said Blaise, a handsome boy who seemed to rival only Draco in his arrogance.

"And I suppose murdering your husbands is a much easier way to get gold, Zabini," Pansy sniffed.

As Draco burst into laughter - much to Pansy's delight - Blaise curled his hands into fists and began to rise from his chair.

"My mother has never — you're even more stupid than you look if you believe those ridiculous rumours, Parkinson."

"Crabbe, Goyle," Draco said lazily with a wave of his hand.

His two eleven-year-old bodyguards moved from their position either side of Draco's armchair and stepped between Pansy and Blaise, looking quite menacing. Blaise gave a derisive snort and marched out of the common room, beckoning Theodore on his way out.

Draco's little group settled back down and Regulus floated over to the bookshelves, where a stack of the current week's Daily Prophets were always kept. He flipped through the pile - the students, as always, had neglected to keep them in chronological order - until he found what he was looking for.

" Gringotts break-in latest… " he read in a murmur, as he smoothed the paper out.

Bizarrely, it appeared that someone had foolishly attempted to break into Gringotts, which claimed to be among the most secure institutions in the wizarding world. Even more bizarrely, they had been successful.

And yet nothing had been stolen: the vault had already been emptied, back in July, on the same day the theft had been attempted.

It was highly unusual for someone to empty an entire vault. Families often kept all their valuables at Gringotts - apart from the ones they kept on display, of course - as well as their gold, there would be hideous heirlooms that nobody wanted, jewellery that their great-great-aunt had cursed on her deathbed, that sort of thing.

Regulus's own, smaller vault, a private off-shoot of the main Black family one, had been filled with galleons, each of his old broomsticks (tenderly lain on velvet pillows), and part of his transfigured horcrux research—

He froze, his hand trembling over the newsprint. He looked back down at the page but it didn't mention which vault had been broken into, because of course it wouldn't, the goblins didn't even want to say what the thieves had been looking for, never mind where they had been looking.

They would have informed him, wouldn't they? If someone had tried to break into his vault? He might be a ghost, he might be dead , but he still had rights, didn't he? It was still his vault, wasn't it?

Regulus sprung into action, cleaving through a cluster of fourth-years who squealed at the icy intrusion and leapt out of his path. He passed straight through the common room wall and up through the dungeon ceiling to the History of Magic classroom on the fourth floor.

"Professor Binns?" he called out frantically, poking his head through the blackboard and into the teacher's office in his desperation.

Professor Binns looked up from the stack of parchment on his desk and blinked owlishly at Regulus.

"Professor Binns," Regulus repeated, swooping through the wall to hover beside his old teacher's desk. "What do you know about Gringotts? Specifically about family vaults?"

"Not a great deal," he said slowly. "I have only written a handful of essays on the subject…"

"Do you— do you know what would have happened to my vault? After I died?"

Professor Binns clasped his ghostly hands in front of his chest and pursed his lips. Regulus, normally appreciative of the care and deliberation the teacher always took when answering questions, felt terribly impatient.

"In normal circumstances, a wizard's vault would be passed to his heir," said Professor Binns.

"I didn't have an heir," Regulus said, irritably.

"No, of course, you were very young… in which case, it ought to have passed to your next-of-kin."

"To Mother. And after her?"

Professor Binns looked up at him, blinking again.

Regulus wilted, floating down to the floor and resting his head on his arms on the edge of Professor Binns' desk.

"Sirius," Regulus groaned into his arms.

"A relation of yours?"

"Yes," Regulus mumbled. "My brother."

He sunk down through the stone floor entirely and drifted back towards the common room. He thought he might haunt the dungeon corridors while he mused about Sirius, the damp cold atmosphere beneath the lake a soothing balm for the fire that burned in him whenever his brother was brought to mind.

Because Regulus didn't like to think about Sirius. Hadn't needed to think about him for almost a decade. And now the Potter boy had turned up and disrupted Regulus's peace with painful memories of bloody James , which necessitated thinking about Sirius and his impulsiveness and his betrayal . And now Sirius had access to Regulus's Gringotts vault, and all the meticulously-collected research within which could, potentially, be more dangerous than anything bloody Lucius Malfoy might be trying to hide.

He thought he had known Sirius. Hated him, at times. Envied him, always. But known him nevertheless. It rankled that Sirius could have spent the entirety of his teenage years yelling his head off about muggle-born rights and equality and justice, could have abandoned his brother, his real brother, for the bloody Potters, and then… what? Betrayed them? Betrayed James? Somehow had his stubborn, obstinate mind turned towards the Dark Lord after all?

It was a joke . That both Black brothers had ended up switching sides - that both had been seized by a madness that resulted in them betraying their friends, betraying their families . That both Black brothers had ended up turncloaks. Traitors.

It was a joke, but the world believed it to be true.

And yet…

"Watch where you're drifting, Black ."

Regulus looked up in surprise and caught a glimpse of Severus Snape's scowl before he spun on his heel, his robes whirling behind him. Regulus rolled his eyes and wondered, not for the first time, if Severus deliberately acted in such a melodramatic fashion just to rub in the fact that Regulus couldn't partake in the enjoyment of swishing his own robes now that he was dead.

"Wait, Severus," he called out, before he had even realised he was speaking.

A distraction from his brother was always a welcome thing, even if that distraction was Severus Snape.

Severus stilled, and glanced over his shoulder.

"A word, if I may?" Regulus said politely.

He turned around fully and glowered. Regulus waited patiently for this little charade to be over; Severus knew full well that Regulus could drift through his office wall and sit on his desk like the irritant he considered him to be until the so-called Potions Master deigned to speak. It wasn't exactly polite, and it was certainly against ghostly etiquette to wander into a living being's private quarters at will, but Regulus had never been against resorting to desperate measures in life, and he certainly wasn't in death.

"Fine," Severus snapped, and Regulus followed him into his office.

It was as dark and gloomy as the man himself, with a handful of flickering candles and shelves stretching up to the ceiling, stacked with various jars and canisters holding all sorts of intriguing things. Regulus stared into a jar full of floating eyeballs, his own eyes widening when one slowly rotated and winked at him.

"I assume you bothered me for a reason and not just to stare at my belongings, Black."

Regulus turned around and forced a benign smile onto his face.

"What do you make of our new first-years?" he asked.

"Just as useless as the last lot," Severus said snidely.

"Even Harry Potter?"

Severus's jaw twitched. "He's every bit as arrogant as his father was."

"Peculiar," Regulus said lightly, swooping across the room to peer at the scattered papers and herbs across Severus's desk. "I thought he seemed quite different. Embarrassed by all the attention he has been receiving. Shy, almost."

"Your wits must have faded as much as the rest of you, Black," Severus spat. "Now if you'll excuse me, I have a detention to administer."

Regulus drifted towards the office door and paused, turning back for one last jibe.

"I have far more reason to hate the child than you do, Severus," he said. "After all, his father stole my brother. The only thing he took from you was the vague hope that Lily could bear to look at you once more."

The fury on Severus's face was delightful to behold and Regulus left, feeling quite pleased with himself as he floated along the corridor to the common room.

He passed Vincent and Gregory - perhaps they were the students heading for detention - and hurried forwards, hoping at last that he would be able to talk to Draco one-on-one without his burly bodyguards looming near.

As Regulus had hoped, Draco was sat, alone, in his usual armchair. He looked rather forlorn without his entourage around him and kept casting sullen glances over his shoulder; Theodore and Daphne looked to be working on their homework together, while the other first-year girls were giggling nearby.

"Hello Draco," Regulus said breezily.

He settled down on the arm of Draco's chair, determined to drag at least some conversation out of the boy. Draco gave an exaggerated shiver and shifted his weight away from his spectral cousin.

"How are you enjoying your classes so far, Draco?"

"Fine," he said, inspecting his fingernails. "Everyone says that I am very talented. Particularly at Potions."

"Very good… and how do you find Professor Snape?"

"He's brilliant, " Draco breathed, eyes gleaming.

Regulus frowned. He didn't think he would have ever expected anyone to describe Severus as 'brilliant' in the context of his teaching abilities - year after year of students had come to him with complaints about the ornery professor.

But Lucius had always been fond of his protégé, and perhaps Severus had known Draco before Hogwarts and gained favour with the boy - odd that Severus hadn't mentioned it during their brief conversation, though.

Still, Regulus felt a flush of regret that he had not been afforded the same privilege - by all rights he should have been Draco's godfather. Narcissa had promised him as much, on his seventeenth birthday, before it all turned to shit.

"He's not like the other teachers, he doesn't care about Potter's celebrity . He doesn't give him special treatment like the rest of them. Did you know," Draco said, sitting up straighter and clearly warming to this topic. "Professor Snape asked the most basic questions and Potter didn't know a single thing! He doesn't even know what a bezoar is, can you imagine?"

"He has grown up in the muggle world," Regulus said diplomatically.

"So?" Draco scoffed. "He's got a textbook, hasn't he? Every five-year-old knows what a bezoar is. Even that stupid mudblood knows more than Potter, squirming about like someone shoved a flobberworm down her shirt."

Draco did a rather insulting impression of this girl, sticking his teeth out over his bottom lip and lifting himself up off his chair, his arm stretched towards the ceiling.

" Pick me, Professor! Oh, pick me, pick me! " Draco squealed, before collapsing back into his chair in fits of laughter.

Regulus gave him a wan smile. Clearly Narcissa had done nothing to school Lucius's language around their son.

"Anyway, Potter ought to be embarrassed at his stupidity but of course he just sits there all smug and arrogant," Draco continued. "Professor Snape sees right through him, of course. Took points off him for being a stupid prat. The Gryffindors are all complete idiots, I don't know why everyone thinks Hufflepuff is the house for morons - Longbottom managed to melt his cauldron and disrupt the entire lesson!"

Longbottom. Draco's aunt and uncle had tortured that boy's parents into insanity. Regulus had heard about it from Phineas Nigellus - Bellatrix had returned to Grimmauld Place to gloat about it to Walburga afterwards. Had told Walburga that she ought to be the heir, that she was more man than either of Walburga's pathetic sons.

Shit — what if Regulus's vault had passed along to Bellatrix, the oldest of his cousins, since Sirius had been disinherited? What if—

"Professor Snape said that my potion was perfect, obviously," said Draco, interrupting Regulus's thoughts. "He particularly praised the way I stewed my horned slugs."

He looked at Regulus expectantly; Regulus blinked, and inclined his head.

"I'm sure your slugs were outstanding, Draco."