The island had not changed. The cave was a world for the dead, and nothing here could grow, or die, or shift in any way Harry could imagine. It was hard to believe that the ocean's waves would ever wear this place away, even given a thousand years.
The island on a sheet of black water, the lake in a cave, the cavern beneath the ocean. This place shouldn't exist, was a thought that drifted over the front of Harry's mind, though he couldn't for the life of him guess where it came from. Perhaps, he mused, it was born from the thought that he shouldn't be here.
Behind Harry was the stone basin, filled with the green poison that once held Slytherin's locket. The rock beneath Harry's hands was cold and rough and blackened, not with soot, but with composition. This cavern had been wrought from black rock, and nothing here could do more than superficially color it for fleeting moments, inconsequential compared to the magnitude of the lifespan of stone.
Harry ignored the empty basin which half-killed Professor Dumbledore. Instead, he looked out onto the water in vain hope of the boat, knowing already somehow that he was not here via some linear path through space. Indeed, the depths were shielded by a surface tension uninterrupted by the old wooden boat. Harry's fingernails scraped gently against the stone, and the rattle seemed deafening in the silence. He could barely hear the sound of the scrape over the sensation of the death-trap he was sat upon grinding against his fingertips.
Harry drew up his legs a bit and wrapped his arms about his knees. It wasn't comfortable, but it left him a decent enough view out over the water. He wasn't sure if he was even facing the entrance to the cave. Every direction melted into shadow at the edges.
Harry didn't know how long he had been staring out over the watery grave before, feet away from the shore, a pale head surfaced. It had grey eyes and a handsome nose which barely peaked over the surface, the rest remaining submerged as the corpse blankly observed Harry's observations. The black hair of the body was plastered to its head, but long enough to reach the water and float out in tendrils barely dark enough to show against the rippling reflection of the stone above them. Their eyes met. Harry knew what legilimancy felt like by now, and whatever this entity hoped to achieve was nothing like it. Whatever being was staring back at him from the water was not searching his memories or thoughts, only his present and his actions. Harry could not tear his eyes away. It was like looking in a mirror. Like if Harry turned his head the body would turn with him, and yet their eyes would stay in tune. Harry blew a deep breath through cold lips. He thought he may know who this was.
"Regulus?" he called out over the cavern. It echoed, but nothing moved. For a moment it was like he'd imagined the sound. Then, the head in the water, eyes unwavering, nodded. Just once.
Harry unwrapped his legs and pushed himself onto his hands and knees. Like Dumbledore all those months ago (it felt like years) he crawled painstakingly to the edge of the water. The head did nothing to move forward, nothing to beckon him. It simply held Harry's gaze with eyes both glazed over with death and dark with searching intelligence. When Harry reached the edge he did not touch the water. He drew himself up to be kneeling just inches away from the end of the island. The body was so close, Regulus was so close, he could have reached out and touched him.
The head rose yet a few inches more. The mouth revealed was thin, set into cheeks now flattened with pallor and decay, yet bearing all the signs of once being flush with puppy-fat and newness.
"You found my locket," spoke Regulus Black. Harry nodded, not breaking their mutual stare. Just once.
Neither said anything more for a long moment. Nothing moved in the cavern, nor possessed color, nor felt anything more than existence, plain and unbedecked.
"How do you know my name?" asked the body of Regulus Black. Harry answered before he realized he'd answered.
"Your brother, he was my godfather. I asked Kreacher what happened. He told me all of it." The head looked, for the first time, aware when Harry told it this. It looked something close to concerned, and close to wistful. With such an expression laid upon himself, Harry felt oddly guilty over the space he'd left between them.
"Did he destroy it?" asked the body, "is it gone? Is the Dark Lord mortal?" Harry shrugged helplessly. The light in Regulus's filmed-over eyes was not light at all, so much as a sort of darkness that shone outward from the rotting black of his waterlogged eyes.
"Yes, and no?" Harry settled on. "The locket was destroyed by a friend of mine in front of my own two eyes. But Tom, he made more. He made six, actually, though it would have been five in your time, I suppose." Regulus frowned slightly. His head tilted and Harry got his first glimpse of Regulus's neck. It was mottled, scraped even, with the shape of what seemed to be many overlapping hands. And teeth.
"Who are you? And why are you here, when you have so much yet to do?" Regulus asked him. Harry had so many answers. He was Harry Potter, the Boy who Lived, the Chosen One, he was here to ask about horcruxes, he was here to learn about Voldemort, he…
"I'm just Harry," he said, "and I'm going to die. Tom is, he's, he's going to murder me."
The head nodded once more, a slight bunch to its brows and a curiosity that looked odd on such a slackened face. The dead, thought Harry, were supposed to look apathetic, somehow. Underneath whatever emotion they died with, wasn't there supposed to be peace? Harry's fists clenched on his knees. His hems were wet, and he hadn't noticed. Harry glanced down, startled, to see small ripples flowing out from where his legs brushed the water. He looked back up and Regulus was inches from his nose.
Harry could not move, could not blink, could not breathe. Regulus, revealed in full, was sluicing off water from rags of clothing and a wasteland of white skin. Not a single drop made a sound as it returned to the lake, even as Harry watched the ripples spread from each abandoned stream.
"I'm seventeen, you know," said Regulus, his lack of breath odd against Harry's face, "I died here. He murdered me, too." Harry shuddered and Regulus's head tipped back until he faced the ceiling. Crouched as he was, he was shorter than Harry. He looked more like a statue, an idol to some Byronic hero, than the corpse of a seventeen-year-old. The same age as Harry.
"Why did you? Why die here? Why do any of it?" Harry croaked desperately, "you couldn't have known it would ever be destroyed, that Tom Riddle would ever die. And now you're here, in the cold and dark. Forever." Regulus did not look away from the heavens he would never see again through the ocean-worn lid of his tomb. Rather, he smiled. A tiny, quirked thing, but a true smile nonetheless.
"I won't be here forever. Someday, the ocean will wash away all trace of this place. And our bodies will be eaten by fish that will be eaten by whales. I knew, from the moment Kreacher told me about this place, that the Dark Lord would meet his end. A being like Kreacher is like a wave beating against the shore. We made him what he is, and it wasn't right at all, and the price is that, bit by bit, everything that has ever happened will be returned. The Dark Lord made his own end. And now, we're both here. At his end."
"How can you believe that?" Harry cried desperately, "He killed you! You're gone. I'm talking to the body of someone who died before I was even born."
"Are you afraid to die?" asked Regulus.
"Yes!" screamed Harry. With an impulsive jerk forwards Harry grabbed the corpse by the shoulders. It wavered, rocked forward and back with Harry's emotions, but stayed upright and steady though it all. "I don't want to be like you. You died, and no one even knew that you were trying! They all think you're a coward death eater who ran off and got himself killed. And now, you've died for nothing! Dumbledore and I would have gotten the locket faster if you'd never done this, it would have been destroyed whether you died or not. The only reason I found it at all is because of some coincidence with a completely barmy house elf who might have died before I ever got to ask him if Sirius had gotten his way."
The flesh beneath Harry's hands was so cold. It was rigid, and wet, and freezing, and moving in a way that was undeniably dead. Harry wished it wasn't here, that he wasn't here, that all of this had never happened. Regulus's head dropped down to face Harry with all of the regard one could have towards a neck that was already broken.
"I know," he said, "I died protecting a house elf, a being almost everyone would tell you is worthless. I put my faith in him. And now a horcrux is gone. I did everything wrong, lived a short life that ended for the sake of a morality I was recruited to help destroy." Regulus took his first, and only breath, then, and water flooded from between barely-parted lips to splatter against Harry's trousers. "But it worked. And now the Dark Lord is a little closer to being dead, directly because of a Kreacher he thought so beneath him as to be worth less than nothing. The Dark Lord will die, because his death is so inevitable it is being brought on by coincidence and victims of his deeds and principles that he espouses as being untrue to the point of lunacy. The Dark Lord isn't simply going to die, he is going to die because everything he has ever believed is wrong." Regulus paused to place a hand on either side of Harry's head. "He believed that the only way someone could defeat him was by killing someone lesser to do so, by force or by betrayal . And because I am here, he is wrong."
Harry was crying, now. Like the water dripping from Regulus's face, the drops made no sound as they fell and joined the water of Regulus's grave. Regulus's cold, stiff fingers were rubbing gentle circles into his temples.
"Wh-when I, die," Harry hiccuped out, "it'll be worth something right? I won't die in vain. I'll be like you." Regulus smiled sadly at him and shook his head lightly.
"Every death is worth something. People like the Dark Lord would have you believe otherwise, that there are lives worth more than others. But every life is meaningful, Harry. Even Tom's. Death, it's just…a wave crashing against the shore. What you do before, that's what matters. And I think you've done quite a lot, believing in a better world than Tom Riddle ever could."
Harry felt quite dizzy now, and Regulus was coming into focus even as the rest of the cavern faded. Even Regulus's eyes seemed to be losing some of the pallor and white film that marked him as passed on.
"I'm dreaming, aren't I?" said Harry to the smiling face of Regulus Black, "you aren't really here." Even as he whispered, he could feel cold hands cradling the back of his head as he was lowered back against the stone island that seemed to feel less material by the moment.
"Of course you're dreaming, Harry," he heard whispered as his world went black, "but why should that mean I'm not with you?"