A quick warning: This posits that Regulus's trip to the lake was a suicide attempt as well as an attempt to stop Voldemort, and Regulus is most definitely not in a healthy mental state. If this may be triggering to you, please take care of yourself.

Sirius Black was just about to go to bed when a loud crack echoed through his flat. Instinctively, he scrambled for his wand, but before it was even in his grip, he realized that whoever had Apparated unexpectedly into his flat was in no state to attack him. The soft sobs and moans of pain made that fairly obvious. Sirius peered closer at the sodden figure curled up on his floor and did a double take.

"Regulus?"

Regulus didn't respond, just let out a small, pained moan and curled in on himself a little more. Sirius dropped to his knees next to his brother and, for the first time, noticed a small figure cowering next to him.

"Kreacher, what the hell is going on?"

"Kreacher cannot tell Master Sirius," Kreacher said miserably. "Master Regulus has forbidden Kreacher to tell anyone what happened. Master Regulus has told Kreacher that the family is safer if they don't know."

"Well Reggie sure as hell isn't!" Sirius snapped, searching for any visible signs of injury on Regulus's body. It was hard to tell with Regulus gasping and shaking. He sounded as if he were crying, but his cheeks were as soaked as the rest of him, and it was impossible for Sirius to tell if there were tears mingled in with the water.

"Kreacher cannot tell Master Sirius," Kreacher repeated. "Master Regulus has given Kreacher his orders. Master Regulus does not want anyone to know what happened."

"Then why the hell did he let you Apparate him here?" Sirius retorted.

Kreacher shifted guiltily. "Master Regulus ordered Kreacher not to bring him home."

"So?"

"Master Regulus ordered Kreacher not to bring him home," Kreacher repeated, looking up at Sirius like he expected Sirius to glean some wisdom from the statement. Sirius couldn't.

"Did he tell you to bring him here?" he asked.

Kreacher shook his head. "Master Regulus-"

But whatever cryptic thing Kreacher was about to say was cut off by another piteous moan from Regulus. Sirius looked back down at him and again tried to figure out what the hell happened. If he could figure out why his brother was so wet, maybe that would help, but it wasn't raining, and Regulus looked more like he'd decided to go for a swim in his robes for some godforsaken reason. Sirius had absolutely no idea what was going on.

"Can you at least tell me what happened to him?" Sirius demanded. "I can't help him if I don't know what did this."

Kreacher started rocking back and forth on his heels. "Master Regulus told Kreacher not to tell anyone," he muttered. "Master Regulus told Kreacher that no one could know. Master Regulus told Kreacher to keep it a secret."

"Master Regulus is an idiot," Sirius muttered, pointing his wand at Regulus and murmuring a diagnostic spell. The worst of the pain seemed to be centered around his abdomen, given the way that Regulus kept curling around it, but there was no evidence of any curse or hex or jinx. Whatever had been done to him, it wasn't something that Sirius could easily fix. There was a cut on his forearm, slicing straight through the Dark Mark, but that wasn't severe enough to explain all this.

"Kreacher, is there any Sleeping Draught in the cupboard?"

Kreacher obediently went over to the potions cupboard. "Kreacher does not see any Sleeping Draught. Kreacher does not see anything that would help."

"Damn," Sirius muttered. He looked down at Regulus again. He couldn't counter a spell if he didn't know what it was. He didn't even necessarily know if it was a spell hurting Regulus at all at all. It could have been a potion, in which case mixing it with Sleeping Draught might have been fine or might have killed Regulus right there. Sirius didn't know.

But Regulus was still gasping and sobbing and moaning, and Sirius had to do something.

"Stupefy," he said desperately, pointing his wand at Regulus, and when the red light hit Regulus's chest, he abruptly went limp. It was the best Sirius could manage and the only thing he could think of that could possibly work.

With a flick of his wand, Sirius levitated Regulus's body and brought it into his bedroom. Regulus was horribly still as Sirius lowered him onto the bed, so still that Sirius had to check twice to make sure he was still breathing. He was, but just barely.

Sirius flicked his wand again to dry Regulus's robes, then he Summoned a chair from the kitchen and sank down into it. He never made his bed, so all the covers were balled up down at the end. Slowly, he used his wand to drape them over Regulus's unconscious body.

Then he looked down at Kreacher, who had followed him into the bedroom, and said, "I know you can't tell me everything, but you're going to tell me whatever you can, and you're going to do it right now."

And Kreacher, of course, obeyed.

Sirius was on his third cup of tea when Regulus finally began to wake. Kreacher noticed first and immediately rushed to Regulus's side. Sirius set his cup aside and leaned forward, watching as Regulus's eyes finally blinked open.

"How are you feeling, Reg?"

Regulus's eyes flew wide open and he let out a startled gasp. He moved like he was going to sit up, then he hissed through gritted teeth and gripped his abdomen.

"I healed your arm the best I could," Sirius said, nodding at Regulus's forearm. "It'll leave a scar, though."

Regulus gripped one hand around his wounded arm, still staring at Sirius. "I would have done something more to help, but Kreacher won't tell me what's wrong with you," Sirius added. "He won't tell me much of anything, actually. Your orders, I assume?"

Regulus looked at Kreacher with wild eyes. "You were supposed to leave me," he said, his tone almost desperate.

"Master Regulus ordered Kreacher not to bring him home," Kreacher replied, looking almost defiant. "Master Regulus did not order Kreacher not to bring him to his brother."

"You were supposed to leave me," Regulus repeated. There was fear mixed in with the desperation, Sirius realized. He hadn't seen his brother show his emotions that clearly for years.

"Leave you where?" he asked.

Regulus looked at Sirius and swallowed. "I need to go."

"I don't think so."

"I need to-"

Sirius pulled out his wand and pointed it at Regulus's chest. Regulus went still.

"You're my brother," Sirius said, his voice as steady as his wand, "and you clearly needed help, so I helped you. But you're also a Death Eater, Reg. I'm not just letting you leave."

"Have you told anyone I'm here?" Regulus asked.

Sirius briefly considered lying, but Regulus always had an annoying knack of seeing through such things. "Not yet."

"You can't tell anyone."

"You can't tell me what to do."

"I'm serious," Regulus said, and some insane part of Sirius wanted to reply, No, I am. "You can't tell anyone."

"I'll tell-"

"I defied the Dark Lord," Regulus hissed. "I stole something from him, and once he realizes I did, he's going to kill me. You cannot tell anyone."

Sirius stared. Reggie, little Reggie, defied and stole from Voldemort? "You did what?"

Regulus's gaze flickered to Kreacher. "What did you tell him?"

"Kreacher only told Master Sirius the things Master Regulus did not tell him to keep a secret."

"He wouldn't tell me any details, but he said that he found out something important, and then you two went off to do something with it," Sirius said. "Feel like filling in the blanks?"

Regulus swallowed hard. "Could I have some water first?" he asked, his voice as politely indifferent as it would be at a family dinner.

Sirius picked up his cup, chugged the last of the tea, and filled it with water. Kreacher helped Regulus lift his head, and Sirius helped him guide the mug to his lips. Regulus's hands were shaking too much to do it himself.

"So," Sirius said once Regulus had gulped down the water, "what happened?"

"A few weeks ago, the Dark Lord requested to borrow the services of a house elf," Regulus said. He was trying very hard to sound emotionless, but there was a hint of a tremble in his voice. "I volunteered Kreacher. The Dark Lord took him to a… a cave." Regulus swallowed. "The Dark Lord hid a locket there and then left. Kreacher returned home and told me what happened."

"Hid a locket?" Sirius repeated. "Huh. Voldemort doesn't strike me as the jewelry type." He ignored how Regulus flinched at the name.

"It wasn't just a locket," Regulus said, a hint of irritation in his voice. "Sirius, what do you know about Horcruxes?"

The name struck a dull chord in Sirius's memory, but nothing clear. "Uh, not much?"

"They're dark magic," Regulus said. "Darker than…" He shuddered. "A Horcrux is created when someone rips apart their soul and hides part of it in an object."

Sirius stared at Regulus with wide eyes. Now he could remember where he'd heard the term; when he was young, he'd found a book in the Black family library that had talked about Horcruxes. His father had taken the book away when he saw Sirius flipping through it. If it was magic too dark for the Black family…

"Are you saying that the locket…"

"Yes."

"But don't Horcruxes make people immortal?"

"Yes."

Sirius let out a groan and ran his hand through his hair. "So we're all screwed then."

"Well…"

"Wait," Sirius said suddenly, looking at Regulus. "That can't be the end of the story. You haven't explained how you ended up like this" - he gestured vaguely at Regulus - "yet. What happened?"

"The cave had protections, of course," Regulus replied.

Sirius gaped at his brother. "Are you saying you stole the locket?"

"What was I supposed to do, leave it?" Regulus retorted. "Horcruxes are dark magic, Sirius. Incredibly dark. And I have reason to believe that the Dark Lord has more than one."

"Is that even possible?"

"It would seem so."

Sirius shook his head, trying to wrap his head around what Regulus was saying. "I need to tell the Order."

Regulus's hand shot out to grab Sirius's wrist. His face was still pale, but his grip was strong. "Don't you dare."

"Reggie, they need to know this. We're fighting Voldemort-"

"You have a spy."

Sirius stared wide-eyed at his brother. "We have a what?"

"A spy," Regulus repeated. "You do know what one is, don't you?"

"Who?"

"I don't know," Regulus admitted. "But the Dark Lord has bragged about it. You can't tell the Order anything about me or about the Horcruxes. He'll know."

Sirius thought for a minute. "Okay, but I'm telling Dumbledore. This is way above my pay grade, and we know he's not the spy."

Regulus didn't look as if he liked that idea too much, but it wasn't like he could argue that Dumbledore was the spy. He was Dumbledore. Sirius was pretty sure the darkest thing he'd ever done was blow out a candle.

"Fine," Regulus finally said, his voice tight. "But Dumbledore only."

Sirius nodded. "I'll tell him now. Stay here."

"I doubt I can go anywhere," Regulus replied peevishly.

"Right. Good. Kreacher, keep an eye on him."

"Kreacher will take care of Master Regulus."

"And don't let him go anywhere," Sirius added.

"Kreacher will take care of Master Regulus," Kreacher repeated.

Sirius sighed. If Regulus told Kreacher to take him away, Kreacher would probably obey him no matter what orders he might have had from Sirius. Kreacher had always been a bit too willing to twist around orders he didn't like, and he definitely listened to Regulus more than he listened to Sirius. Hopefully, though, he'd understand that Regulus probably shouldn't be moved, and if Voldemort was potentially going to come after him for stealing a piece of his soul, Sirius's apartment was much safer than Grimmauld Place.

Sending a Patronus message to Dumbledore was easy, although Sirius had no idea what to say. I have information about Voldemort that you really need to hear as soon as possible, was what he ended up going with. He hoped Dumbledore would get back to him quickly.

Thankfully, Dumbledore's graceful silver phoenix appeared a few minutes later. "I will arrive at your apartment at eight o'clock in the morning," it said in Dumbledore's voice before disappearing into thin air. Sirius breathed a sigh of relief and headed back into his bedroom.

Regulus was doubled over, clutching his torso and gasping in pain. Kreacher was next to him, clearly trying his best to help, and Sirius rushed to his other side.

"Reggie! Reggie, what's wrong?"

"Hurts," Regulus whispered.

Sirius bit back the urge to tell him exactly how helpful that response was. "What can I do?" he demanded instead.

"Water," Regulus croaked after a moment, and at least that was something Sirius could help with. He grabbed his cup and filled it with water, then he pressed it to Regulus's lips. Regulus nearly choked on the first mouthful and spat it out onto the sheets, but he was able to swallow the second mouthful, and the third, and the fourth. Before too long, he'd drank the whole cup, and while he was still trembling and clearly in pain, he seemed somewhat better.

"Do you need more water?" Sirius asked warily.

Regulus shook his head weakly, leaning back against the pillow. His arms were still wrapped around his stomach.

"Did you contact Dumbledore?" he asked, his voice somehow dry and rasping even though he'd just chugged a full cup of water.

"He's coming in the morning," Sirius replied. "Are you up for that?"

"I will be," Regulus said grimly.

"I can tell him to come later," Sirius offered, even though he really shouldn't.

Regulus's mouth twisted slightly. "You've never coddled me before, Sirius, don't start now."

"You never Apparated into my apartment half-dead before," Sirius countered. "I wish you hadn't started now, but you did."

"I didn't Apparate here," Regulus corrected. "Kreacher brought me here. I didn't want him to."

"Right, sure, you probably wanted to go back home," Sirius replied, rolling his eyes. Even as he said the words, though, he remembered what Kreacher had said Regulus's orders were. "Master Regulus ordered Kreacher not to bring him home."

Before, Regulus had said that Kreacher was supposed to leave him.

"Reggie," Sirius said slowly, "you didn't want to go home, did you?"

Regulus didn't say a word.

"Did you think you'd be leaving that cave at all?"

Again, Regulus was silent.

Sirius swallowed. "Did you think you were going to die?"

Regulus didn't answer, but he didn't have to. Sirius knew what his answer would be. For a moment, he tried to imagine what it would have been like if Kreacher hadn't found a loophole in Regulus's orders, if Regulus had simply disappeared one night and never come home. He and his brother weren't necessarily close, but it hurt to even imagine Regulus being gone. And to think that apparently Regulus had planned that, maybe even wanted that…

Sirius didn't ask why. He didn't beg for answers, or demand them, or even say anything else about it. He just reached out, took Regulus's hand, and squeezed it lightly.

"We'll figure this out," he said, and he hoped Regulus believed him.

Regulus clearly couldn't be moved, so Sirius slept on the couch. "Slept," honestly, was a generous term, so generous it bordered on being a complete and total lie. He lay on the couch and strained his ears to hear any and every sound that came from the bedroom. Kreacher had had to return to Grimmauld Place, so Sirius was the only one there to take care of Regulus, and he intended to do it well. The bedroom was mostly silent all night, though, and as far as Sirius could tell, Regulus didn't have another fit. He hoped it wasn't just that Regulus was hiding it from him.

At seven o'clock, with only one hour to go until Dumbledore would arrive, Sirius decided to give up on the whole concept of sleep in general and instead got up to make himself a pot of tea. He drank a cup, then poured a second cup for himself and a cup for Regulus. He wasn't sure how Regulus took his tea anymore, so he left it plain and grabbed the sugar bowl on his way to the bedroom.

Regulus appeared to be sleeping at first, but his eyes flew open so quickly when Sirius stepped into the room that he couldn't really have been sleeping at all. "Feeling better this morning?" Sirius asked, sitting down next to the bed.

"I'm fine, thank you," Regulus replied primly.

Sirius handed him his cup of tea. "Not sure how you take it, so…" He offered the sugar bowl, but Regulus shook his head.

"Plain is fine," he said, taking a sip. Sirius remembered how Regulus used to hate tea when he was younger and would only drink it if it was so sweet you could hardly taste anything but the sugar.

Sirius silently took a sip from his own cup. "Dumbledore will be here in about an hour," he said after a moment. "You ready?"

"I am."

"You're gonna tell him the same thing you told me last night, I guess?"

"Indeed."

"Anything else?"

Regulus shot Sirius a look. "I assume you'll insist on being there when I speak to Dumbledore. Can't you just wait to see what I'll say to him when he's here?"

"Mmm, I'd rather not."

"Do you have any patience at all?"

"Not really."

Regulus rolled his eyes.

Sirius grinned. He was just thinking about how it was kinda nice to spend time with his brother again when he remembered what else they'd talked about - or, more accurately, didn't talk about - the night before, how Regulus hadn't intended to survive the night. Whatever protections were in the cave, Regulus had thought they were going to kill him. Regulus had planned for them to kill him.

Regulus had specifically told Kreacher not to save him, and that only failed because he'd left an accidental loophole. If he hadn't, he would be dead.

"I'm gonna go tidy up the sitting room a bit," Sirius said, standing. "So it's nice when Dumbledore gets here. And then he can come through to here-"

"Absolutely not," Regulus interrupted firmly. "I'll meet with him in the drawing room."

"First of all, I don't have a drawing room, just a sitting room, and second of all, no way."

"I'm not meeting with Albus Dumbledore while lying in a bed like some sort of invalid weakling."

"You are kind of an invalid, Reggie."

Regulus's jaw set. "I will speak with Dumbledore in the sitting room, or I won't speak with him at all."

Sirius gave him a dirty look. "You don't have to be so damn proud all the time, did you know that?"

"Just because you have no sense of your own self-worth doesn't mean that I don't," Regulus retorted.

"Oi, I know exactly how amazing I am! Anyway, is it really your own self-worth if it only comes from what your last name is?"

Regulus looked down his nose at Sirius, managing to look an awful lot like their mother. "Don't you have a sitting room to clean?"

"Yeah, yeah, whatever."

Sirius didn't end up doing much to tidy the sitting room, partially because he wasn't very good at cleaning and partially because he was too busy keeping an ear out for Regulus to be able to think about much of anything else. He was glad when he looked over at the clock and saw that it was a quarter to eight. That gave him the excuse to stop pretending to clean and head into the bedroom to have one last chance at beating some sense into Regulus's head.

When he entered, Regulus was attempting to stand, so apparently that would be even harder than Sirius had thought.

"What the hell are you doing?" Sirius demanded. "Get back in the bed, you idiot!"

"I will not meet with Albus Dumbledore in this bed," Regulus said firmly. He'd managed to sit up and swing his legs over the edge of the bed, but his face had gone white with the exertion and his arms, which were the only things keeping him upright, were trembling. If he actually managed to get himself on his feet, which Sirius doubted would happen, he'd probably fall flat on his face.

"You bloody idiot," Sirius hissed. "You nearly died, get your stupid arse back in that bed now-"

"I will not-"

"Regulus Arcturus Black, I swear on Merlin's name, you will get back in that bed-"

"You're not my mother, Sirius."

Sirius gave Regulus the dirtiest look he could manage. "You're an idiot. You're a complete and total idiot."

"I'm not-"

"Yeah, I get it, you're not meeting with Dumbledore in the bed." Sirius sighed. "You have to make everything so damn complicated, don't you?"

Regulus set his jaw. His stubborn face looked a lot like Sirius's own, and if he was even half as stubborn as Sirius was, he wasn't going to give in. "Fine," Sirius huffed. He wasn't going to fight this battle. He had the feeling that he was going to get in a lot of fights with Regulus before this was over, and this one wasn't worth it. "I'll help you out into the sitting room, you'll sit on the couch, and you can meet with Dumbledore from there."

"That's acceptable," Regulus agreed after a moment.

"You're a bloody pest, did you know that?" Sirius said, bending down to wrap his arm around Regulus's torso. Regulus slung an arm around his shoulders and allowed Sirius to pull him to his feet. With their bodies so close, Sirius could feel that his brother's whole body was shaking. He was almost tempted to dump him back on the bed, but then Regulus would just try to get to the sitting room by himself, so Sirius walked them slowly to the couch, then set Regulus down. Regulus had somehow managed to turn even paler than he was before, but he managed to sit upright on the couch, his hands only slightly trembling when he folded them in his lap.

"Okay," Sirius said. "Dumbledore should be here any minute. Anything you need?"

"No."

"You sure? A drink, something to eat, anything?"

Regulus was silent for a moment, then said, "A glass of water, please."

Sirius went to the kitchen and poured a glass of water, then went back to the sitting room and handed it to Regulus. Regulus's hand shook as he lifted it to his mouth, but he was able to drink it without spilling and carefully set the glass on the side table when he was done with it. Sirius was about to ask why Regulus was drinking water like there was no tomorrow when there was a knock on the door. "That'll be Dumbledore, then," he said instead, going to the door. He checked through the peep hole before opening it.

"Professor. Thanks for coming."

"Of course, Sirius," Dumbledore replied. "Your message sounded urgent. I apologize for not being able to come earlier."

"This is fine," Sirius replied. "Uh, come in."

He stepped aside to let Dumbledore pass. If Dumbledore was surprised to see Sirius's Death Eater brother sitting on the couch, he didn't show it.

"You can sit, if you want," Sirius said, gesturing vaguely at the chairs in the room. "Uh, do you want anything? Tea?"

"No, thank you," Dumbledore replied, sitting in an armchair. "Good morning, Regulus."

"Professor Dumbledore," Regulus replied, his voice a bit cool.

"I assume, Sirius," Dumbledore added, "that your brother's presence has something to do with you calling me here."

"Yeah, Reggie's the one with the information," Sirius said. "It's… He should tell you. He knows more than I do."

"Is that so?" Dumbledore asked. "What information do you have to share, Regulus?"

"I assume, Professor, you know what a Horcrux is."

Dumbledore's face went solemn. "I do."

Regulus reached into the pocket of his robes and pulled out a heavy gold locket. Even from across the room, Sirius could feel the dark magic that radiated from it. He was seized with the desire to smack it out of Regulus's hands, but he controlled himself.

"This belongs to the Dark Lord," Regulus said. "I stole it from him last night. And I have reason to believe that he has more than one."

Sirius had never seen Dumbledore look as grave as he did then.

"Tell me everything."

Dumbledore and Regulus talked for hours. Sirius could tell that Regulus's strength was starting to wane less than an hour in, but his brother managed to stay sitting upright, as far as Sirius could tell, out of sheer force of will. Sirius discreetly kept the glass of water at his side full.

Despite Dumbledore's directive, Regulus didn't tell him everything. He told him a lot, yes, but he was clearly keeping some things back. It was a delicate game, the sort of politics that Sirius had never been particularly good at. Regulus was telling Dumbledore enough to get him started, enough to prove his worth, but he wasn't telling him enough to make himself expendable. If Regulus told Dumbledore absolutely everything, he'd lose his insurance. Sirius was fairly certain Regulus didn't need that insurance, given how much incredible, war-altering information he was providing, but Regulus had always been more cautious than him.

One of the things Regulus refused to talk about was the cave where he'd found the locket. Sirius knew it had to have protections, both because Regulus had said so and because of how terrible his condition had been when he first arrived in Sirius's flat, but otherwise, he didn't know a thing about it. Regulus went pale and tight-lipped every time Dumbledore asked. He wouldn't tell him where the cave was either, just that it was "dealt with." Sirius thought there had to be something else about the cave that was bothering him, more than just whatever the protections did to him, but he wasn't sure. He couldn't read his brother nearly as well as he used to.

When Dumbledore finally left, Sirius had hardly closed the door behind him when Regulus slumped and began to fall forwards off the couch. Sirius caught him right before he hit the ground. Regulus's entire body was shaking like a leaf, and he felt ridiculously light and painfully thin. That, Sirius knows, couldn't be attributed to the cave, at least not entirely. He wondered how long it had been since Regulus had taken proper care of himself.

Then again, a wicked part of Sirius's mind reminded him, Regulus had never intended on living past the cave. Why bother taking care of yourself when you knew you were about to die?

"If you were feeling this faint, you should have said something," Sirius said, his voice a little snappish from worry. "Dumbledore would have understood, even if you refuse to tell him anything about what happened in the bloody cave."

"The cave is dealt with," Regulus said. His voice was weak. "There's no reason for him to know anything more about it."

"Taking a look at the protections around that Horcrux might make it easier for Dumbledore to prepare for protections around the other Horcruxes."

Regulus shook his head vehemently. It occurred to Sirius that pressing Regulus about this when he was clearly traumatized probably wasn't the best idea. That was probably why Dumbledore had laid off him so quickly. Sirius figured he should probably follow Dumbledore's example, even though he really wanted to know what had happened. He'd give Regulus a few days to recover before he pushed.

"Let's get you back into bed, then," Sirius said, heaving his brother to his feet. "Are you going to go back to sleep? It's about lunchtime, if you're hungry."

"I'd rather sleep, unless you have something else you need me to do," Regulus replied.

Sirius nodded. "Okay. Look, I know you told me not to tell anyone you were here, but if I make him promise not to tell anyone, can I tell James? Cause I'm supposed to have dinner with him and Lily tonight, and I'll need some sort of excuse."

"You don't need an excuse," Regulus countered. "Go to dinner with them."

"And leave you here alone? Hell no."

"I am an adult, Sirius. I can stay here alone."

"Sitting on the couch for a few hours was too much for you," Sirius said in a dry voice. "How the hell do you plan to take care of yourself for a night?"

Regulus scowled. "I'm not a child, Sirius."

"You literally just told me you were an adult, Reggie. I get it." Sirius dumped Regulus onto his bed and shrugged. "Doesn't mean you don't need help."

It was true, but it wasn't the entire reason. There was also a part of Sirius that was terrified that, if he left Regulus alone, he would come back to find that he was gone. He couldn't stop thinking about the fact that Regulus had meant to die in the cave. Regulus had meant to die. Sirius didn't think he'd try to kill himself without reason, but he also wouldn't have thought that Regulus would be willing to accept death so easily in the first place. The fact that Regulus was there, still alive, meant that going into the cave wasn't necessarily a death sentence, but Regulus had intended for it to be. Sirius had the sinking feeling that Regulus might have wanted for it to be. Like hell he was going to leave Regulus alone.

"So can I tell James and Lily or not?" Sirius asked. "They won't tell anyone. I trust them."

"If I tell you not to tell Potter, will you listen to me?" Regulus countered.

"What's that supposed to mean?"

"I know you care about him more than me," Regulus said, some bitterness in his voice. "He's the brother you wanted. If I tell you to lie to him, will you even do it?"

"Of course I will!" Sirius cried. "I mean, I don't have to, because James will keep your secret, but if you want to be paranoid-"

"I don't think wanting to keep the fact that I stole from the Dark Lord a secret is paranoia," Regulus argued.

"It is if you want to keep it from people who would never let it slip."

Regulus crossed his arms tightly over his chest. "Don't tell Potter."

Sirius sighed. "Reg-"

"You said you'd keep it from him if I wanted you to," Regulus reminded him. "I don't want you to breathe a word of this to anyone but Professor Dumbledore, and only in confidence."

"You really are a paranoid little bastard, aren't you?" Sirius sighed, but at least Regulus wasn't being suicidal anymore. Overly-paranoid was probably better. "Fine, I won't tell James. I'll come up with some other reason I can't go to dinner. No one will know."

Regulus looked tentatively satisfied. "Good."

"What about Mum and Dad?" Sirius asked. "What are they going to think? Can Kreacher tell them what happened?"

"Kreacher is forbidden to tell them anything," Regulus said. "I think my orders should stand against any attempts made by Mother or Father."

"Then what are they going to think?" Sirius asked. "Are you going to visit them? Tell them what's going on?"

"They can't know," Regulus said, lips pressed tightly together. "You know what our… extended family is like. If Mother or Father said anything to Uncle Cygnus or Aunt Druella, and they said something to Bellatrix…"

"You'd be screwed," Sirius said succinctly. "So what are you going to tell Mum and Dad?"

"Nothing."

Sirius stared at Regulus. "So, what, you're just going to let them think you've disappeared? That you're dead?"

"I don't have much of another option," Regulus hissed back. "I didn't plan for this. I-"

"You didn't think you'd make it out of the cave," Sirius finished. "And if you're dead, you don't have to give a damn about anyone else, right? Why care about whether Mum and Dad would ever know what happened to you? It won't be your problem anymore."

"Are you on their side, then?" Regulus asked coolly.

"What? No!" Sirius protested immediately. "I'm just- Reg, if you'd died in the cave, then we would never know what happened to you."

"And all of you would have been much safer," Regulus said. "I did this to protect you, Sirius-"

"Do you have any idea-"

Sirius cut himself off before he could say something he'd regret. He didn't really want to tell Regulus how much his death would have hurt, especially considering the status of their relationship. He did want to chew Regulus out for assuming he knew what was best for everyone when he was only eighteen goddamn years old, but that would probably get dangerously close to admitting that Sirius would have missed Regulus if he were gone. And that would come dangerously close to admitting that Sirius had missed Regulus every day for the past three years.

There were some things that just couldn't be said, not yet.

"You're an idiot," was what Sirius settled on saying instead. "And you can't do that to Mum and Dad, no matter how shitty they are. Write them."

"And say what?" Regulus countered. "That I'm in hiding?"

"That you're off traveling," Sirius said. "It's a decent enough excuse, and it'll cover up you being gone. Come on, Reggie, you know people are going to notice before too long, and then you'll be screwed. What are you going to do when Cousin Bella realizes that you haven't been at any of the family tea parties?"

"Bellatrix never comes to tea," Regulus said primly. "And what excuse would I give for leaving without a word? What excuse would I give if Mother asked me to come home to visit? I can't go back, Sirius. I can't put our parents in danger because of my choices."

"Mum and Dad pushed you into those choices," Sirius argued. "They shoved you towards the Death Eaters. If they get caught in the crossfire now-"

"They're still my parents, even if you refuse to claim them," Regulus spat. "I'm not going to leave them to die."

"You'll just let them think you died."

"It's the lesser of two evils, Sirius," Regulus snapped. "If Mother and Father think I'm dead, they're safe. That's why I left them in the dark. That's why no one was supposed to know what happened to me."

"Well thank Merlin that Kreacher ruined that," Sirius retorted. "That was a stupid plan."

"It was the best plan I could come up with to protect the most people," Regulus retorted. "If things had gone as they were supposed to, no one but me would have been in danger."

"And you'd be dead," Sirius said sharply. "Poor planning, Reg."

"I didn't-"

Halfway through the sentence, Regulus's face went white and he doubled over, his breaths suddenly ragged. He wrapped his arms around his stomach tightly, clearly caught in the same sort of painful fit as last night.

"Reg?" Sirius demanded, grabbing Regulus's shoulder. "Reg. What's happening?"

Regulus hissed out something incomprehensible through clenched teeth.

"What?" Sirius demanded. "Reg-"

"Stun me," Regulus spat.

Sirius recoiled. "What? No-"

"Stun me," Regulus repeated. "N-Nothing else will-" He hissed sharply. "It hurts, Sirius."

"I can get you more water," Sirius offered desperately. "That worked last time, didn't it?"

Regulus shook his head, biting back a groan. "Please, Sirius."

Sirius stared at his brother for a long moment, then he pulled out his wand and aimed it at Regulus. The tip only shook slightly as he whispered, "Stupefy."

Regulus went limp and slumped backwards. Sirius lowered his wand quickly and checked Regulus's pulse, but it was close enough to steady that he didn't think he needed to worry. There were no signs of pain on Regulus's face anymore, so Sirius hoped the Stunning spell did what it was supposed to do.

Screw giving Regulus time. Screw following Dumbledore's example. The second that Regulus woke up, Sirius was going to demand some answers.

Regulus slept for hours, straight through dinner and into the early evening. Sirius sat by his side and waited for him to wake. He only left to eat dinner, and only after setting a charm that would alert him the second that Regulus stirred. He didn't.

When Regulus did wake and Sirius saw his eyes begin to flutter open, he picked up his teacup and filled it with water, expecting that Regulus would want something to drink. He held it out to his brother before Regulus was even fully conscious.

"Here."

Regulus blinked. "Sirius?"

"Take the cup," Sirius said. "I'm sure you're thirsty. You've been asleep for hours."

Regulus took the cup. Sirius helped him lift it to his lips and drink.

"I have questions," Sirius said as they lowered the cup back to its saucer, "and I want you to answer them."

The expression on Regulus's face immediately turned cagey. "Questions about what?"

"What the hell do you think I have questions about? You go off to die in a cave, and you think I won't ask questions?"

Regulus flinched. "The cave is dealt with."

"Yeah, and I want to know what you had to deal with."

"Nothing that concerns you."

"If you Apparate into my flat half-dead, I think whatever almost killed you is my concern."

"I didn't ask for Kreacher to bring me here!" Regulus protested. "I didn't want him to!"

"You wanted him to leave you to die," Sirius said. "Do you see how that just makes me more concerned?"

"It would have been better for everyone if he had!" Regulus cried. "The Dark Lord will come after me. He won't rest until I'm dead."

"How will he even know? We can figure something out-"

"He'll know."

"How? He's not all-knowing, as much as he might tell his followers otherwise. We can-"

"I left a note!" Regulus yelled. "I left a note in the locket! I wanted the Dark Lord to know it had been me."

"Why the bloody hell did you leave a note?" Sirius demanded. "Did you put your name on it?"

"I wanted him to know it was me," Regulus repeated. "I didn't expect to come out of there alive. I didn't think it would be a problem."

"What about the rest of us? If he knew it was you, what would stop him from going after me, or Mum and Dad?"

"He's going after you anyway, you're with the Order. And he won't go after Mother and Father."

"How do you know?"

Regulus scoffed. "Because they're Orion and Walburga Black. He can't go after them without alienating half his base. I needed him to know, Sirius. I needed him to know he didn't own me. I didn't think I would ever come out of that cave again."

Sirius was silent for a long moment. Regulus was shaking, a fine trembling that spread over his entire body. Perhaps Sirius ought to leave him alone, but Sirius had never been very good at leaving well enough alone, and he needed to know the truth.

"Reg, what was in the cave?"

Regulus wrapped both hands around his teacup and slowly lifted it to his lips. He took a long sip, then set it down in the saucer in his lap.

"The cave was surrounded by the sea," he said, his voice so soft it was barely audible. "To get in, you had to give a blood sacrifice to the door." He held out his arm, showing Sirius the long, thin cut that bisected the Dark Mark burned into his forearm. "Inside the cave, there was a lake. I took a boat to a little island in the middle. On the island, there was a basin."

He stopped talking for so long, Sirius thought he might have to interject, but just as he opened his mouth to do so, Regulus began to speak again.

"There was a potion in the basin. At the bottom, under the potion, was the locket, and the only way to reach the bottom of the basin was to drink."

Regulus went silent again. "What was the potion?" Sirius finally asked.

"I don't think it has a name," Regulus said, his voice still so very quiet. "It made me… see things. Horrible things. It made me…" He licked his lips. Sirius silently refilled his cup with water, and Regulus drank again.

"When I finished the potion, I took out the locket. I had Kreacher swap them. And then… It made me so thirsty, so I dipped my hands into the water of the lake, and I drank."

"Alright," Sirius said. The way Regulus said the words gave an eerie sense of finality, but Sirius didn't know why. "So you drank. What does it matter?"

A slow, humorless smile spread over Regulus's face. It looked like a grimace.

"The lake was full of Inferi," he said quietly. "And once their waters were disturbed, they struck. That's why I thought I would die. That's why I told Kreacher to leave me. The Inferi would drag me underwater. It was a simpler, kinder death than what the Dark Lord would give. It was more than I deserved."

"Reg-"

"I'm a Death Eater, Sirius." Regulus's face twisted. "Don't tell me you'd think any differently if I weren't your brother."

"You're trying to fix things now," Sirius countered. "You're trying to make things right. For Merlin's sake, Reg, you're only eighteen bloody years old. You're a kid."

"I've been of age for over a year," Regulus replied. "I made my own decisions. I regret them, and I wish I hadn't, but that doesn't change the past. That doesn't change what I did."

"Then work to make things better. Don't just go and off yourself."

"I stole the Dark Lord's Horcrux," Regulus said dryly. "What else am I supposed to do, exactly?"

"You said you think there are more," Sirius replied. "Help us find the others. Help us destroy the one you already found. Help us end the Dark Lord, once and for all. It won't change the past, but maybe it can make up for it."

"I'm not sure anything can make up for it," Regulus murmured, in a voice so quiet Sirius wasn't sure whether or not he was meant to hear it.

"You won't know until you try."

For a long moment, Regulus was quiet, staring into his empty teacup. Finally, he spoke.

"I'll still need to fake my death. The Dark Lord needs to think I'm dead."

"We can manage that," Sirius agreed. "What about Mum and Dad?"

Regulus turned the teacup in his hands, still not looking up. "For now, I don't think we should tell them anything. Let them think I'm dead too."

Sirius wasn't sure he agreed that was the best idea, but he also didn't think that arguing with Regulus about it was the best idea, so he kept his opinions to himself. "Will you join the Order?"

Regulus's lips twisted upward, just slightly. Sirius wasn't quite sure if he could really call the expression a smile. "You've got a spy, remember? The Dark Lord won't think I'm dead for long if your Order finds out the truth."

"Right." Sirius didn't like to think there was a spy in the Order, but if Regulus told him there was, he believed it. It would explain some things, even if Sirius didn't like this particular explanation. "So, what, you'll work directly with Dumbledore?"

"I imagine I ought to discuss that idea with Dumbledore," Regulus replied. "But… Yes, perhaps that would work."

Sirius nodded. "Right, well, whatever you do, talk to me about it, yeah? Don't just run off on a half-baked suicide mission. You should have talked to me before you went on this last one."

"We haven't exactly been on speaking terms recently," Regulus countered. "Besides, what could you have done?"

"Well, first off, I'd have told you not to leave a signed note."

The hint of a smile flickered across Regulus's face so quickly Sirius almost thought he was imagining it. "I did want the Dark Lord to know it was me, but in retrospect, that might not have been the wisest decision."

"And, look, Reg…" Sirius sighed. "No matter how angry I am with you, no matter whether or not we're on speaking terms, you can always come to me with important stuff like this. If you'd died in that cave…" The words caught in his throat, and he shrugged. "I'm glad you didn't."

Regulus was quiet for a long moment, so long that Sirius didn't think he would respond. He stood and turned to leave, figuring he probably ought to send Dumbledore a message with the update.

"Do you know," Regulus said, just as Sirius was about to step through the door, "I think I'm glad I didn't die as well."

Sirius smiled.