The passage of time concerns the living far more than it does the dead.

After all, what is a mere hour, or even a month, in comparison to the whole of eternity stretching out before you like a vast, unfathomable ocean? Or like a dark lake in a dark cave, its edges blending into a darkness so deep it makes your eyes ache to look at it, your head ache to try to calculate its vastness.

And during the long, stretching summers time passes even more peculiarly for the dead. Without the familiar beats of daily school life - classes, mealtimes, Quidditch practices and matches - the days all begin to blend together. Yesterday could be in three weeks' time. Tomorrow could have happened months ago. Tuesdays and Saturdays and Mondays and Fridays all jumbled up, mixing together like potion ingredients.

What is time, anyway, but a construct of the living? An attempt to partition their brief lives into briefer segments, in the hopes of deriving some sort of meaning from their daily grind?

That is to say, as Regulus drifted down the empty corridor, lost in his thoughts as he was wont to do, he had no idea that today was the first of September, let alone that the year was 1991. He had no idea that the castle was about to be inhabited by a child with Black blood for the first time since his own graduation or, more disturbingly, that the Potter child was also due to make his debut into the magical world.

"Regulus, my friend!"

Regulus paused his thinking and his drifting and looked up, blinking his still-grey eyes in surprise at the sight of the ghostly horde streaming down the corridor towards him.

"Do you care to share your thoughts on how we might proceed with this Peeves situation, Regulus?" asked the Friar as he glided closer.

"The Peeves situation?"

Sir Nicholas approached Regulus's other side, his ridiculous plumed hat poking through Regulus's head in a manner that would have been decidedly uncomfortable if he weren't as translucent and unfeeling as the next ghost.

"I have said it before and I shall say it again," said Sir Nicholas, "the welcome feast is no place for a poltergeist."

"I say we ought to live and let live," said the Friar, chuckling at his own joke.

"I suppose Peeves was somewhat disruptive last year," Regulus said carefully.

Peeves had spent most of the last first of September lying in wait underneath the staff table in the Great Hall. He only emerged once the welcome feast had been served, soaring up through the tabletop, skewering a whole roast chicken on his head before he began dancing quite inappropriately on top of Severus Snape's dinner plate.

Regulus hadn't been the only one in the Great Hall that evening who had tried to hold back his laughter, but he did think that he had been the most successful. The headmaster really ought to have shown more dignity.

"I am sure that our mischievous friend has learned his lesson," said the Friar.

"Poppycock!" said Sir Nicholas, thrusting his chest out. "Peeves is a terror. A menace!"

Regulus listened to the two senior ghosts' argument as they all drifted through the castle, nodding and making appropriate thoughtful noises whenever called to. He didn't particularly mind whether the poltergeist attended the feast or not - although he supposed that Peeves would liven things up a little if he did attend. This year's sorting ceremony would be Regulus's… eighteenth? Nineteenth? It was difficult to keep track of those sorts of things, when you were a ghost.

Sir Nicholas would be able to tell him, of course. Sir Nicholas had a particular fascination for dates and calendars - Regulus suspected it was because he had lingered through the introduction of the Gregorian calendar - and kept an enormous one in an abandoned classroom which he used to count down to all the Hogwarts' ghosts' Deathdays.

But Regulus didn't want to ask Sir Nicholas, because he didn't want to encourage further conversation about his own youthful afterlife, didn't want to encourage Sir Nicholas to call him 'whippersnapper' any more than necessary, didn't want to be told yet again how lucky he was to have such a thrilling death tale to tell.

Regulus didn't find the events surrounding his death thrilling at all.

He was just glad that ghosts didn't have to sleep, because he suspected that his nightmares would end up killing him all over again.

They floated down the grand staircase, Regulus and Sir Nicholas and the Friar and all of the other ghosts of the castle, and drifted towards the Great Hall. But as they slipped through the wall of an ante-chamber Regulus froze, letting the others pass straight through him, because there, right in front of him, was a crowd of children.

And he realised that the ghosts' debate - still ongoing - about whether to allow Peeves to attend the welcome feast was for nothing, because the welcome feast was tonight.

Regulus hovered half-way through the chamber wall as he tried to regain his bearings. His eyes were drawn to a bright shock of ginger hair among the dark robes and dark pointed hats. Another Weasley, he thought piteously, hoping that this one would take after Percy rather than those rambunctious twins. And next to the Weasley—

No.

Regulus would have retreated right back through the wall again and sped off to the tallest, loneliest turret to sulk and grumble in peace if Lady Helena, bringing up the rear of the ghostly horde, hadn't smiled that shy smile of hers and beckoned him forwards.

Because next to the Weasley was a small child with a mess of dark hair, the very likeness of Regulus's nemesis, that hateful Potter who had stolen his brother as though the fight for Sirius's affections were a mere sport.

The child must have turned eleven without Regulus's knowledge. Without his say-so. Regulus stuck his nose in the air and followed Lady Helena through the ante-chamber and into the Great Hall; she was right, of course. He oughtn't spend an eternity brooding over an idiot Potter who didn't even exist anymore. Still, Regulus didn't dare to look at any of the other first-year children, terrified at the prospect of seeing yet more of his tortured memories turned flesh.

The Slytherin house ghost, the Bloody Baron, was sat sullenly at the end of the table furthest from the door. When he spotted Regulus drifting towards him he upped and left, taking a seat at the other end, beside the Head Girl; she made a valiant effort at concealing how uneasy she was about the new seating arrangements. Regulus resolved to ask the house-elves to take something to her as a reward, perhaps an extra blanket for her bed in the chilly Slytherin dormitory.

Regulus sat himself among a group of second-years talking at a disturbingly rapid pace about their excitement to witness their first sorting ceremony from this side of the Great Hall.

The girl sitting beside him - Verity Avery, excellent Herbologist - turned to greet Regulus with a smile, which he forced himself to return.

"Are you looking forward to meeting Draco?" she asked.

"I'm sorry?"

"Your cousin, Draco Malfoy!" Verity said, laughing as though he had made a joke.

"Oh. Right. Of course; yes. Very much so."

In truth, Regulus hadn't realised that his cousin's son would be starting at Hogwarts this year. He had heard the news of Draco's birth from his great-grandfather, Phineas Nigellus, who had been able to provide him with vague and irregular family updates through his linked portraits in the headmaster's office and at Grimmauld Place for as long as Walburga had remained alive.

Draco had been born nine months after Regulus's death.

Regulus had always found the timing rather odd.

Still, he was eager to meet this boy. He wondered whether Draco would take after Narcissa, or Lucius - he wondered whether Draco had any younger siblings, perhaps born after Walburga had passed. He wondered how much Draco knew about him, if Narcissa had told her son about her once-favourite cousin (not that there had been much competition at the time, Regulus thought, ruefully) or if Lucius had prevented her from telling their child anything at all about the family turn-cloak, the blood-traitor.

Regulus wondered if Sirius had usurped his position in Narcissa's affections, as bizarre as that sounded.

A pair of large boys and a girl with straight blonde hair had joined the Slytherin table before it was Draco's turn to be sorted. Regulus turned to watch in anticipation: the boy carried himself like his father had done - a pity - but his delicate features were all Narcissa's. The Sorting Hat had barely brushed against the top of Draco's head before it yelled out 'SLYTHERIN!' and Regulus joined in the applause even though his ghostly hands were unable to make a sound.

Draco sauntered over to the Slytherin table and the two bigger boys slid apart to make room for him. Regulus chivvied a small dark-haired girl out of the way - she seemed most put-out - and sat opposite his little cousin.

"Hello," Regulus said, smiling eagerly. He hoped the dark scratches on his neck weren't too visible, or too spooky, in the flickering candlelight. "I've been looking forward to meeting you, Draco."

"And you are…?" asked Draco with a sneer.

"I'm your cousin—"

"I thought my cousin was in Azkaban," Draco said, looking Regulus up and down.

"No, that's my brother Sirius," Regulus said, feeling quite wrong-footed by this small, pointy-faced boy. "I'm Regulus. I died before you were born."

"Oh. Well I've never heard of you."

Draco turned away from Regulus and went back to talking with his two heavy-set friends. Regulus sat in silence and raised a pale hand to his chest, feeling a phantom ache where his heart had once beaten.

"He's incredibly rude, not at all like I expected," Draco said loudly. He had drawn the attention of all the new first-years, as well as half the second-years. "Wouldn't even shake my hand. Of course, he was raised by muggles so I suppose it's no surprise that his manners are lacking."

"Did you see the scar?" the blonde girl asked.

"Yes. Hideous thing. Nothing to get all excited about."

The scar. Regulus looked back towards the staff table, his eyes widening as he saw that the miniature version of his nemesis was sat waiting to be sorted. He seemed to have been there quite a while; the rest of the hall was filled with whispered gossip, with students craning their necks to get a good look at the so-called Boy-Who-Lived.

And when the hat finally announced that this Potter - Harry, Regulus remembered, belatedly, a terribly boring name - would be joining the Gryffindors, just as his father had done, Regulus rolled his eyes and tried to block out the thunderous applause.

Draco continued bad-mouthing Harry throughout the duration of the feast, telling anyone who would listen how he had gone to introduce himself to the boy on the Hogwarts Express, intending to ease his transition into the wizarding world and get him started on the right foot. Apparently the latest Weasley child had already 'dug his dirty claws in' and dragged Harry 'down with the rest of the blood-traitors'.

Regulus restrained himself from commenting, but only just.

"He'll go the same way as his parents," Draco said airily. "They've never known what's good for them, the Potters."

"Don't worry, Draco," said the dark-haired girl. "We don't need the likes of that little brat, not in Slytherin."

She leaned through Regulus to stretch across the table and pat Draco's pale hand; he jerked it away, scowling.

"I'm not worried," he scoffed. "Pass me those potatoes, Crabbe. They're the only thing here worth eating. Father warned me that the Hogwarts elves wouldn't be up to scratch but I didn't expect their cooking to be this awful."

Regulus smiled at this comment, remembering how terrible he had found the Hogwarts fare during his first term, too. While it was true that the house-elves in the kitchens didn't have quite the finesse that he and, presumably, Draco had been used to as children, that wasn't to say that they were terrible cooks. Just different.

"You'll get used to the food," Regulus said, launching into another attempt at talking to his cousin. "Do your family still have Dobby? He made the most excellent custard tarts, if I recall correctly."

"Yes," said Draco, still scowling. "But I shan't get used to this. I will write to Mother as soon as we get to the common room. She can't expect me to eat this slop until December."

After the feast had concluded Regulus helped the Slytherin prefects guide the students on their short journey out of the Great Hall and through the dungeons to their common room. He found himself in the company of the Slytherin Chasers, now in their third year and desperate to prove themselves.

"We've been practising all summer," explained Graham. "Different formations and that. Adesy's dad put hoops up in the paddock, didn't he Ade?"

Adrian nodded. "Yeah. Lots of injuries, but at least Charlie got to practice on us."

Adrian's sister, Charlotte, had finished at Hogwarts last summer and gone straight into training to become a Healer at St Mungo's.

"My arm's still a bit sore," Cassius said, rubbing his elbow.

"He's fine," Graham said hurriedly to Regulus. "Will you come to try-outs? Flinto hopes there'll be some new Seekers. Reckon he'll decapitate Higgsy if he's as crap as last year."

"Language," Regulus said half-heartedly.

"He can't be any worse," Adrian snorted.

"What kind of Seeker has never caught the snitch?" sniggered Cassius.

"I'll come to try-outs," Regulus said, glancing around in case poor Terrence Higgs happened to be nearby and had overheard his teammates' slander. "I'm sure Terrence has spent his summer practising just as much as you three have."

Once they reached the common room the three Chasers hurried over to the coveted armchairs beside the fireplace, only to be moved along by a group of snarling seventh-years. Regulus left them to it and turned his attention to the new students: Draco was hurrying off in the direction of the dormitories with the two bigger boys. The others had gathered themselves together in the centre of the room, most looking quite uneasy but trying to hide it. The dark-haired girl - Pansy, Regulus thought she had been called - was gazing wistfully after Draco.

"Hello," he said gently as he drifted over to the group. One of the girls gave a start; an unfortunate muggle-born among the Slytherins, perhaps. "My name is Regulus. It wasn't so long ago that I was in your position, fresh-faced and full of nerves. I hope that your next seven years in Slytherin are filled with happiness and excitement, but I want you all to know that you can come to me if you have any worries, or fears, or anxieties. I can assure you that I have probably had experience with whatever it is that is on your mind."

He smiled at them. A couple of the girls gave nervous giggles.

"You'll usually find me here in the common room during the evenings," he continued. "Or in the library. Or at Quidditch matches, of course."

"Do you play Quidditch?" asked the taller of the girls. "Sorry— did you play?"

"Yes, I did. I was Seeker for six years," Regulus said proudly.

She cooed; the dark-haired girl, Pansy, gave him a scrutinising look.

"You said you were Draco's cousin. Were you a Malfoy?" she asked sharply.

"No. My family name is Black."

The few children who hadn't been paying attention now looked up at him, their mouths dropping open slightly.

"Is that a bad thing?" whispered the muggle-born girl. The tall girl shushed her, elbowing her sharply.

Regulus gripped his hands tightly behind his back and looked about the room, embarrassed as he always was by the attention that his name brought. Perhaps one of these years he would pretend to be someone else, someone insignificant… a Yaxley, perhaps.

Luckily for Regulus, the Head Girl chose to make an appearance and hurried all the first-years off to find their beds and get a good night's sleep before their classes began. Regulus waved farewell and drifted over to one of the tall windows that looked out into the depths of the lake, alternating between looking out for merpeople and watching the fierce chess match being played out near the smaller fireplace.

The common room quickly emptied - students, no matter their age, were often wearied by the long journey to Hogwarts - but Regulus lingered by the window. He could well recall his first night at Hogwarts, how odd and unfamiliar everything had felt, how cold and lonely he had been despite being surrounded by more people than he ever had been before in his life.

He had crept out of bed that first night to sit in this very position, unable to sleep. And while Evan had been there to comfort and reassure him, Regulus knew that not every child was as fortunate as he had been to come to Hogwarts with a friend already made.

So he waited beside the window, just in case he was needed.

Some time after midnight, as the embers in the fireplaces were dwindling and the common room was succumbing to darkness, Regulus heard movement. He looked towards the dormitories and saw a thin, weedy boy standing in the doorway.

"Hello," Regulus said softly. "Would you care to join me?"

"I didn't mean to disturb you, I'll just…"

"I wouldn't mind the company if you were willing. The afterlife can be quite lonely."

The boy gave him a shy smile and hesitantly crossed the room to sit beside Regulus on the window ledge, his shoulders hunched up by his ears. Regulus couldn't recall if the boy had introduced himself at dinner.

"My name is Regulus," he prompted.

"I remember," the boy said. "I'm Theodore. Theodore Nott."

"It's very nice to meet you, Theodore."

Regulus turned back to the window and watched Theodore out of the corner of his eye. The boy was twisting his hands in his lap, stretching his pyjama sleeves down over his hands and pulling at the threads there. Regulus was reminded of how he used to do the same thing, how his mother would scold him for looking unkempt, how he had learned to hide the damage he had done to his clothing.

It was a shame he couldn't now hide the damage he had done to his body.

"Are you related to Iris Nott, by any chance?" Regulus asked, breaking the silence.

"She's my aunt," said Theodore. "She's a Parkinson, now. Pansy's mum."

"Ah. That explains Pansy's… hmm."

Regulus coughed, just about managing to prevent himself from badmouthing an eleven-year-old in front of her classmate.

"Did you know Aunt Iris?" Theodore asked.

"We were at school together, although I didn't get along with her particularly well."

"But she's a lot older than— oh. Sorry," said Theodore, looking away as his cheeks flushed pink.

"I was eighteen when I died in 1979," Regulus said quietly. "I expect Iris looks quite a bit more mature than I do by now."

"Yeah, just a bit."

Theodore gave him another small smile and shifted on the window ledge so he could look out into the lake. They sat in silence for a while, watching stringy pieces of seaweed and the odd grindylow drift by.

"It feels weird, being underwater," Theodore said.

"It does."

It had taken Regulus years, after his death, to be able to sit beside the windows and look out into the water again. Even now, years later, he sometimes shuddered to see his pale reflection; still imagined that he could see the inferi hurtling towards him through the water, their long nails clawing at the glass window as they tried to scratch and bite and drown him once more.

"I grew to find the sound of the water comforting," Regulus murmured. "Peaceful. I hope it will be the same for you."

"Is it true, about the squid?"

"There is a giant squid that lives in the lake, yes," said Regulus. "It's particularly fond of strawberry jam on white toast."

Theodore jerked his head up, wide-eyed in surprise.

"If you cut a slice of toast into long strips and float them on the surface of the water, you might see the squid pop up to feed," Regulus explained. "A most impressive sight."

"Draco said it didn't exist. That it was just a stupid story for children."

"Draco was wrong."

Theodore nodded uncertainly. "I'm sorry. I know he's your cousin."

"It's no matter," Regulus shrugged. "Do you know Draco well?"

Theodore shifted and began pulling at his sleeves again.

"Our fathers are business associates," he murmured.

"I understand."

Regulus knew very well that the term 'business associates' had little to do with business for families like the Malfoys and the Notts… and the Blacks. He could still remember the coded language he had learned to use at school during his teenage years, when it was not possible to speak too plainly even with your closest friends, for fear that they would spill your secrets to the Ministry. Or, worse, to the Dark Lord himself.

"I met your father once or twice."

Theodore looked up again in alarm. "During… during the war?"

Regulus nodded. He wondered how much Theodore had been told about the extent of his involvement in the war, or the actions that had led to his death. His first few years as a ghost had been difficult, with children of both sides of the war furious at or terrified of him: the children of Death Eaters knew him as the Black heir turned traitor; the others as a villain killed either for his hubris or his cowardice.

No one had known the truth, of course. No one knew the full truth, even now.

"If there is anything you wish to discuss with me, about… about anything," Regulus said quietly, watching Theodore's reflection in the window. "I will listen. I may not be able to provide answers or solutions, but I will always listen."