Blood Brothers
Part 1 of 3

Rating – T (cursing, canon death)
Characters – Sirius, Regulus, James (no pairings)
Disclaimer– Sometimes I think I own Sirius and Regulus… then I wake up.
A/N – Parts of Regulus and Sirius' childhoods are shamelessly ripped from my own life (though my parents are decidedly better parents and people than Walburga and Orion). This is dedicated to my brother (who will never read it and I will some day forgive for the worm thing) as well as to Kileaiya for being my beta and because her "Rather Depressing Not-So-Random Facts About The Brothers Black" forced this idea to the forefront of my mind.
Additional Note - This was meant to be canon-compliant when I started it. But, thanks to Deathly Hallows, that's no longer possible. It's close, but there will be one significant scene toward the end of part three that makes it non-canon. Sorry, but the story really needs that bit to be complete.

Summary – Sirius and Regulus wanted to save each other. In the end, neither brother could even save himself.

i.
Sirius' hand is already cramped from writing apology letters to Narcissa, her parents and his own father for tarnishing the family reputation, but the bucket full of flobberworms aren't going to cut themselves and he's not allowed out of his mother's potions laboratory until the project is done. At this rate, he thinks, that might be when he's shipped off to Hogwarts. He's been locked up for five hours now, writing letters and slicing the slimy potions ingredients to his mother's exacting specifications.

It's dark and there's almost no ventilation in the potions lab, which has no windows and only three sconces with mostly-burned candles flickering dully against the cold stone walls. He curses his mother underneath his breath and gets a rush of adrenaline at his own daring. After all, one never knows where Kreacher might be lurking about.

If Sirius were to stop and think about his punishment, he might realize he actually had stepped over the line a bit. But, Sirius isn't that kind of boy, so instead he blames his mother and remembers his exploits fondly.

The pungent odor of rot and sulfur forces Sirius' aristocratic nose to wrinkle involuntarily as he grabs another one of the squirming creatures and chops it clean in half. Really, he decides, the flobberworms were far more entertaining while alive and being dropped down the back of Narcissa's bathing suit then they were in small, stinky, dead parts.

If it weren't for the intolerable stench perfuming the room, Sirius would probably be starving. He's certainly missed supper by now, but mother made the terms of his punishment very clear and there's to be no food or respite for him until he's finished the task at hand. This is why he's more than a little surprised to see the door creak open quietly and his brother slip into the room with a plate of chocolate cake.

Regulus looks nervous as hell but there's a daring sort of grin on his face that looks more like something Sirius should see in the mirror than on his brother.

"What's this, then?" Sirius asks wiping his sullied hands off on his robes, suddenly hungry in spite of the odd mixture of smells permeating the room.

"What's it look like?" Regulus grins. "S'chocolate cake, idiot."

Sirius rolls his eyes at the small boy and tries not to stare at the food.

"I can see that, mugglebrain," Sirius says dryly. "What's it doing here? Did mother send you to taunt me with it?"

"No," Regulus insists indignantly. "I snuck it from the kitchen because I thought you might be hungry, but if you're going to call me names maybe I'll just eat it myself."

"You started it!" Sirius hisses, but he's already headed to the room's only sink to wash his hands as thoroughly as possible. As much as the smells of flobberworms and chocolate cake do not mix, he's certain the tastes would compliment each other even less.

"No, I didn't!" Regulus protests. "You started it by being an idiot. Can hardly blame me for pointing it out."

"Right," Sirius says in a sarcastic, falsely bored voice. "Because certainly it's idiotic to think mother might find more ways to punish me."

"Whatever," Regulus sighs. "Do you want the cake or not?"

"Well… so long as it's here," Sirius says, trying his best to look only vaguely interested.

Regulus, despite Sirius' insults to the contrary, isn't stupid. He snorts knowingly as he hands Sirius the food and watches him devour it almost ravenously.

"Thanks," Sirius says a moment later, licking bits of icing from his fingertips and having the grace to look at least a little ashamed of questioning his brother's motives. "You didn't have to do this and I know mother would have your hide if she knew."

Regulus looks uncomfortable for a moment and stares at his toes.

"Yeah, well… people starve to death, you know!" Regulus finally blurts out.

"Not in five hours," Sirius says looking a bit amused.

"Well I don't know how long it takes!" Regulus protests. "I didn't want you to die or anything."

Half of Sirius wants to call his brother a mugglebrain again, but the other half is a bit touched to see that his brother actually cares.

"They probably wouldn't care if I died," Sirius finally says melodramatically, thudding his head against the wall with feigned casualness.

"Course they would," Regulus counters, giving Sirius that you're an idiot look again.

Sirius is surprised to find himself fleetingly hopeful that perhaps in his lengthy solitude his mother or father has secretly shown some sort of concern or affection toward him.

"You're their heir, aren't you?" Regulus asks then.

"Right," Sirius drawls, instantly let down.

"Anyhow," Regulus continues, not picking up on Sirius' disappointment. "I'm glad you're my brother."

"Yeah?" Sirius asks, wondering at once why his voice sounds needy.

"Yeah," Regulus replies. "I wouldn't want to be their heir. It's easier being second in line. They don't care so much."

"Thanks Reg," Sirius says dryly. "Glad to know I'm good for something."

Sirius privately wonders if it's better to be ignored by their parents or the focus of their undivided attention, but he knows there's no way he'll ever compare notes with Regulus on that topic, so the conversation slides into nothingness until Regulus looks at him with a secret kind of sly grin.

"Besides," Regulus whispers conspiratorially. "The look on Narcissa's face was bloody hysterical."

Sirius grins widely at this as he discovers, for the first time, that a prank is so much better with an appreciative audience.

"I didn't get to see it," Sirius says. "Was behind her with the flobberworm and all."

"Her eyes bugged out like a house elf," Regulus snickers with a full fledged grin and a look of awe.

Sirius' eyes light up at the look of admiration on Regulus' face and suddenly all of this – the hand cramps and the letters and the slippery, putrid flobberworms – they're all worth it.

"I'm glad you're my brother, too," Sirius says finally.

"You are?" Regulus asks, looking a bit skeptical.

"Yeah," Sirius confirms. "Otherwise I'd never know what Narcissa's face had looked like during that prank, would I?"

"Idiot," Regulus grumbles affectionately as Sirius ruffles the younger boy's hair.

ii.
By this afternoon Sirius will be allowed to do magic, which is the most brilliant thing ever. He knows a few spells already, of course – some of which will be taught at Hogwarts and some of which definitely won't. But, he's never been allowed to actually cast a spell because even though his parents seem to view the law as something that doesn't pertain to Purebloods, they haven't been willing to risk his Hogwarts acceptance by citations for violating the Decree for the Reasonable Restriction of Under-Age Sorcery.

Sirius waves his brand new wand around as though he's conducting for some sort of unseen orchestra while Kreacher packs his things for Hogwarts. He was so excited about leaving for school that he'd starting packing his things himself, but that had only resulted in an hour-long lecture from his father about how such menial work was beneath the heir to the Most Noble and Ancient House of Black.

"Kreacher hopes young master will make mistress proud," the elf mutters to himself as he folds Sirius' best dress robes and places them carefully in the trunk. "Mistress worries how the mudblood lover Dumbledore will influence the heir."

Sirius rolls his eyes at this and practices the motions for Wingardium Leviosa with great flourish. He shall be the best wizard ever, he decides suddenly, picturing an Order of Merlin pinned to his chest and a reporter from the Daily Prophet begging him for an interview. Then his father will look at him with respect and his mother will look at him with pride and it will have nothing to do with being their heir, but have everything to do with being their son.

"Oh how mistress will be shamed if young master does not do well at Hogwarts. Mistress knows that young master is too fond of trouble. Yes, mistress wishes the other son were her heir instead," Kreacher grumbles.

"Shut up, you stupid toe-rag," Sirius demands irately, wondering not for the first time if Kreacher's insanity is genuine or some plot of his mother's to continually remind him of his duties. "I'm going to be the best wizard ever."

Kreacher looks at Sirius skeptically, but says nothing since he's been ordered into silence.

Stupid house elf, Sirius thinks. What does he know?

His trunk is nearly packed and Sirius is still imagining himself being interviewed by the Daily Prophet about his Order of Merlin and how he handled juggling his role as Head Boy with Quidditch Captain and still managed to save a first-year from a dragon when Regulus appears hovering uncertainly in the doorway.

"You can come in," Sirius says haughtily, using the wand like a royal scepter and lounging with a lazy regality on his bed. "I've not hexed the doorway… yet."

Regulus pulls a face at this but enters anyhow, still not saying anything but shifting back and forth with a nervous energy that Sirius is used to seeing from the nine-year-old. All at once it occurs to Sirius that despite his mother's apparent wishes that Regulus were her heir, it's a damn good thing he's not. There's nothing Regulus hates more than confrontation except, maybe, attention. Regulus is far happier to fade into the woodwork than to be in the spotlight. All-in-all, Sirius thinks that works out rather well for him.

"I'd transfigure you into a piece of furniture, but I'm not sure anyone would be able to tell the difference," Sirius says after a few moments of total silence.

"You can't do transfiguration, yet," Regulus replies snippily.

"Can't and not allowed are different things," Sirius smirks. "I'm going to be the best wizard ever, you know."

Regulus looks unsettled at this again and sighs heavily.

"Yeah," Regulus says. "I know."

Sirius' wand movements falter at that and he looks at his brother with genuine surprise.

"You do?" he asks.

"Yes," Regulus confirms, slouching in such a way that would earn him a stern admonishment were their parents nearby. "You're already brilliant at everything, aren't you? Why should magic be any different?"

Sirius grins with haughty pride and puffs his chest out a bit.

"And while you're off being all brilliant, I'll be stuck here by myself for two whole years and you'll forget all about me," Regulus says sullenly.

"Don't be stupid," Sirius says with an impatient sigh. "You're far too annoying to forget about."

Regulus shrugs a little, obviously disbelieving Sirius, and plops down inelegantly on the edge of Sirius' bed.

"How many brothers do you think I've got, mugglebrain?" Sirius taunts further.

Regulus smiles a little at this and looks up at his brother with nervous grey eyes.

"S'just me," Regulus says when it becomes apparent that Sirius is actually waiting for an answer.

"Right," Sirius says superiorly, gesturing expressively with his wand. "And no matter what happens at Hogwarts, that's never going to change."

"Yeah," Regulus agrees, finally consoled some.

"So, in two years you'll come to Hogwarts, too. And then, the both of us will be the most brilliant wizards ever, together. Okay?" Sirius asks.

Regulus blushes at this, because he's never really been the best at anything and he's not actually sure that he'd want to be. It's harder to hide in the crowd when you're the best at something. But he agrees with Sirius because that's a lot easier than contradicting the older boy.

Kreacher, who is still silent after being ordered to shut up, closes the lid to Sirius' trunk with finality and drags the heavy case from Sirius' room.

"It's probably about time to go," Sirius says lazily, as though he's not so excited that he might burst.

"You'll write to me, right?" Regulus blurts out suddenly as the two of them follow Kreacher out of the room.

"Course I will," Sirius confirms. "I'll tell you all about Hogwarts. And then when you get there too we'll have all kinds of fun together."

Sirius claps his hand on his brother's back as they leave the room and his mind wanders back his earlier daydream. Only, this time, Regulus is standing next to him and they've both got an Order of Merlin and Sirius is still Head Boy, but Regulus will be too when he's in seventh year. And, they're both in Quidditch uniforms and the reporter is just dying to talk to both of them because they saved that first-year from a dragon together. And it's all perfect, Sirius thinks, because they'll be the best wizards ever, together.

iii.
When it's time for Regulus to start school, he sits with his brother and his brother's friends on the Hogwarts Express. He knows of them, of course, thanks to Sirius' increasingly infrequent letters and his mother's occasional rants, but he's never met them before today. All the same, he dislikes James Potter instantly.

James is everything Regulus is not. He's confident and dramatic, brilliant and mischievous. James and Sirius speak in half-formed sentences that make sense to no one else and they laugh at inside jokes that Regulus will never understand.

There's a closeness there that Regulus thinks he used to have with Sirius. But two years is a long time when you're eleven and they've grown apart as they've grown up. Regulus wants to shout at Sirius, remind him that they're supposed to be the most brilliant wizards ever together; not Sirius and James. But, Regulus is not the daring, noisy type that Sirius would be in his position. So, instead he sits silently next to Sirius' pudgy friend, across from the ill-looking one, and fumes. It's not really James' fault, but Regulus blames him anyhow.

"Is ickle Reggikins nervous about starting school?" James teases suddenly, bringing Regulus' intense dislike to sheer loathing in an instant. "Did your big brother tell you about the giant squid that eats first-years?"

"Oi, lay off him," Sirius says, shoving James in the arm.

Regulus allows a tiny smile, secretly thrilled that his brother stood up for him against James, of all people.

"Oh come on," James protests. "I just asked him if he was nervous."

"Pick on someone your own size," Sirius challenges, quirking an eyebrow and raising his chin proudly. "He's just a kid."

James' eyebrows shoot up until they're entirely hidden by the frames of his glasses.

"Who are you and what have you done with Sirius Black?" James demands, smirking as he pulls his wand on Sirius and the chubby bloke next to Regulus laughs like it's the funniest thing he's ever seen.

"Shut up," Sirius grumbles, batting the wand out of his face. "Brothers are off limits, is all. You wouldn't understand. You don't have a brother."

"What the hell do I need a brother for?" James laughs, slinging an arm around Sirius' shoulder. "I've got you."

Regulus waits for Sirius to protest, to tell James he's only got one brother and that's Regulus – not James. But Sirius never does. Instead, the older Black clocks James upside the back of the head and shoots him a sarcastically questioning look.

"So, if it were me, you'd let someone convince me I was about to be eaten by a giant squid?" Sirius asks.

"If you were gullible enough to believe it, yes," James counters, locking an arm around Sirius' neck in a wrestling move that leads to a far-too-active tumble in a far-too-confined space.

Regulus supposes this is nothing new for the two boys, since the ill-looking friend pulls his legs out of the way without ever looking up from his book and the pudgy one just rolls his eyes and pops another chocolate frog in his mouth.

"If you get a detention before we even get to Hogwarts mother will go spare," Regulus says finally, interrupting the ruckus.

James and Sirius stop instantly and look at each other, to Regulus and back again.

"So he's one of those is he?" James asks. "Before you know it you'll have a brother as a prefect, Sirius. He's going to ruin the family reputation if he's not careful."

Regulus and Sirius have been lectured their entire lives about the importance of the family reputation and Regulus cannot believe that anyone would make light of such a thing. If Regulus were just a little more daring, or just a little more angry, he'd have set James Potter straight about the family reputation right then and there. But, Sirius seemed to actually sense the tension building between the two and diffused it as quickly as he could.

"Come on, mate. He doesn't even have a house yet. Let's not condemn him to a life of boring meetings and shiny badges already," Sirius says with a forced laugh.

"Ah, but which house will he be representing with his prefecture in a few years?" James muses, tapping his wand against his lips in mock deep thought.

"Father says I'll be in Slytherin," Regulus offers with a haughty gaze as James shrivels his nose in distaste.

"Father doesn't know everything," Sirius snaps with enough vitriol that the sick-looking boy closes his book and gives the conversation his full attention.

"You're not supposed to disrespect father like that!" Regulus hisses.

"It's loyalty like that that'll earn you a spot in Hufflepuff," Sirius announces, rolling his eyes at the idea. "Imagine! Me with a brother in Hufflepuff, of all houses."

"Loyalty isn't a bad trait," Regulus reminds his brother through gritted teeth, trying ever-so-hard to maintain his composure. "But, judging by how you talk about father, I suppose I understand that far better than you."

"I'm loyal to the people that deserve it," Sirius snaps coldly.

With that, the elder Black collapses back into his seat, effortlessly elegant. James rests his knobby elbow against his friend's shoulder while the tubby boy tosses Sirius a chocolate frog and the sick-looking boy offers a small, pleased smile.

Something heavy settles low in Regulus' stomach as he watches the scene of easy familiarity unfold in front of him. All the sudden, it is obvious that his place is not by Sirius' side – not anymore. That seat is held by James, with all his charisma and daring filling the space indisputably. Regulus sits apart from the group, an unwelcome reminder of the home Sirius is grateful to escape for most of the year.

Sirius has made himself a new family. So, now more than ever, it is obvious to Regulus that he has to do everything he can to keep the family he has left.

Two hours later, Regulus demands that the sorting hat put him in Slytherin. The hat, in all its wisdom, wants to put him in Hufflepuff.

iv.
Sirius is brash and bold, a whirlwind of life that seems unpredictable to everyone but Regulus. But then, Regulus watches Sirius' life like spectators watch Quidditch – with a view from the stands but never part of the game.

These days, the closest he gets to playing is when Sirius grabs his elbow on the way into the Great Hall and says "Avoid the pumpkin juice, today" with muted bravado There is always a pause when this happens, like Sirius wants to say more, but in the end he is too stubborn to look past the green and silver tie and he walks back to James and Remus and Peter who are eyeing Regulus with undisguised suspicion.

"Like brothers, those two," Professor McGonagall huffs one day, clucking her tongue at Sirius and James when all the chairs in the Great Hall start levitating during lunch.

The two boys smirk with mischievous eyes and identical looks of feigned innocence that no one buys and Regulus realizes it's true. They are like brothers, look like brothers even, with the same dark hair and sharp features and twin grins. Embittered by the realization, Regulus scowls and stalks off, never catching the fleeting look of dismay on Sirius' face as the elder brother loses his audience.

It is the Christmas of Regulus' third year and it is cold in more ways than one. Sirius sits with James, but not Remus or Peter, on the train back to London. When Regulus comes to find his brother as the train pulls into the station, the older boy is solemn and silently staring out the window with a scowl as he kicks the empty bench across from him.

If he is like this with James, Regulus has no doubt things will be even worse at home. He is not wrong.

They are barely home two days when Sirius and his parents get into a row that Regulus can hear quite clearly from his room upstairs. Words like honor and traitor and loyalty and blood are tossed about like Bludgers and Regulus realizes immediately that this can only end one way.

There are thundering steps of angry feet taking the stairs two at a time and a resoundingly slammed door and then, for a moment, silence. Regulus does not breathe in the fragile calm, as though he is afraid he will shatter if he makes a sound. Instead, he pinches his eyes shut and he dares to hope he is wrong. But, Regulus knows his brother well, so he finally releases a shuddering breath when he hears the steady thud thud thud of Sirius' trunk being dragged down the stairs.

There is no more shouting downstairs, in either anger or desperate pleas. In fact, there is only a small pause when Sirius reaches the foyer and, though Regulus cannot make out the words, his mother utters something low and dark that sounds like bile and reeks of hate. Then, there is another slammed door, more resounding this time, echoing through the house like a tomb.

"Good riddance," Orion grumbles as he heads up the stairs and Regulus knows he means it.

There is a knock a moment later, but no pause for an answer before Walburga opens the door and stands in the threshold, staring at Regulus like she's never seen him before. He wonders, briefly, what he looks like to her and when she last bothered to look.

"You are the heir now," she says finally, with disdainful appraisal. "You'd best start acting like it."