Summary:

"Selkies steal your heart. Merrow drown your children. Sirens sink ships," Ron whispered, eyes downcast now. "Everyone knows that. There's a reason wizards aren't big into going swimming and sailing."

Harry sank, wide-eyed, to the bottom of the tank, a massive lump in his throat. Hermione nudged Ron with her foot, tipping her head towards Harry reprovingly. Ron dragged his eyes up again and grimaced.

"Not that… not that I think you'd do those things," Ron said awkwardly, glancing at Hermione and then shuddering. "But… you could."

Harry shook his head, curling his nauseatingly flexible tail against the smooth walls of the tank. He hadn't meant to imperio Hermione - he'd never!

Except, he had, hadn't he?

Monster.

Warnings: Whump with a happy ending. Rated for violence, non-sexual nudity, and later mentions of adult themes.

General Notes: Cross-posted on Ao3, where you can read the full tags (links don't work; same title, same author name).

Neville is going to be a frequent POV character, but will only enter into the scene around chapter ten, as the story largely follows canon at Hogwarts until then and I didn't see the need to write canon from an alternate POV.

Important Note on Canon and Timeline: This is canon-compliant up until The Deathly Hallows. I can't remember why I did it, but I shifted the timeline a little bit so that the fall of the Ministry happened right at the beginning of the summer after sixth year. The horcrux hunt so far has proceeded similarly to canon, though they've gotten to things a bit faster. When the trio is caught by Snatchers, it is the end of August. This story picks up there, at Malfoy Manor. I would love to just say it follows the canon timeline, but I'm too afraid of messing up some detail I wrote into the story and forgot about if I do.

Additionally, you may notice that Ollivander is not a prisoner of Malfoy Manor. This is because, though I am working around the horcruxes, I will not be writing the Hallows. Horcruxes were set up well in advance in the series; the Hallows were not. They would only distract from what I want to write.

Future Updates & Schedule: I have a full draft of this fic already written, so I have every confidence this fic will be completed. My outline predicts this will be thirty-two chapters long. However, updates are posted irregularly because I am taking chunks of that draft and rewriting them to fit a few new ideas I had, before I edit, proofread, and post. For anyone wanting a ballpark estimate, I believe I've managed to update once every two to three weeks so far.

Without further ado, I hope you enjoy!

Draco studied Harry's swollen face carefully before his sharp eyes lifted to Harry's. Something lit in them: recognition. The Slytherin seemed to hesitate before he glanced over his shoulder towards where his father waited next to Bellatrix.

"It's Potter."

Bellatrix let out a peal of delighted laughter and skipped forwards. Harry took a bracing breath and clenched his jaw, glaring at Draco.

"Itty bitty Potter! Did you really think making yourself look so ugly would help you? Hm? Poor Potty Potter. The Dark Lord will be so pleased!" Bellatrix danced around him, cackling, before whipping her wand out to point it towards Harry's right eye. "I can make you even uglier," she whispered, grinning.

Lucius Malfoy stepped up to join her, waving Draco back to the edge of the room.

"We have a job to do, Bella," he said smoothly. "The ritual chamber is prepared."

Bellatrix withdrew her wand and threw her head back, the spark of madness in her eyes flaring into bonfires. "Oh, oh yes! Let us see Potty Potter going flip-flop, gaping like a fish!" Her giggling was so high pitched that it seemed to scrape against Harry's ears.

Ritual chamber? Weren't they going to kill him?

Harry yanked at the snatchers' grip on his arms, but they only shoved him down so that his knees hit the glossy tiles with a painful click. Harry's teeth slammed together, narrowly missing his tongue.

"Take the other two to the cellar," Lucius ordered.

"No!" Harry shouted, struggling to push himself to his feet again as snatchers dragged Hermione and Ron out of the room. He heard Ron cursing as both of them struggled, but it wasn't long before the sounds faded.

"Let them go!" Harry shouted, still pushed against the cold floor. "It's me he really wants, isn't it?"

"Oh, without a doubt," Lucius drawled. "You'll receive special treatment, rest assured. Bellatrix, would you show our guests to the ritual chamber?"

"I'm going to let our Lord know we have Potter," she pouted. "You show them, Lucy."

Despite the adrenaline racing through Harry's body, he couldn't help blinking at the ridiculous nickname for Malfoy senior.

"Very well," the aristocrat bit out, clenching his hand on the head of his cane. "Then call Severus as well and tell him to bring the required potion. When you speak to our Lord, be sure to mention my preparedness in having the ritual ready, Bellatrix."

Bellatrix only smirked before she twirled out of the room, singing a wordless ditty.

"This way," Lucius said stiffly, following her with a much more stately stride. The snatchers yanked up on Harry's arms, dragging him over slick tiles and through heavy wooden doors. Harry made it as difficult for them as he could, and managed to draw several hissed curses from his captors before they reached their destination. Draco trailed behind them the whole way, silent.

It was a plain room that seemed to be carved entirely out of a block of marble. A large runic circle had been drawn in pristine black lines over the floor, but otherwise, the space was featureless. Just outside the doors, Lucius stopped and rounded towards Harry.

"Strip."

Harry scoffed. "No way."

"Cooperate and I can promise that this will be much more pleasant."

"And let Tommy have his way? Not a chance."

Lucius frowned and withdrew his wand, pointing it at Harry.

"Imperio."

It disoriented Harry for a moment. He heard the soft, lulling command to disrobe, accompanied by that strange sense of peace…

He shook his head and grinned up at Lucius. "Try harder, maybe?"

Lucius made a small, exasperated sound in the back of his throat. "I was trying to avoid barbarity, but so be it, Potter." He jerked his chin towards the snatchers. The smaller of the two let go of Harry's arms and withdrew a knife, while Draco joined the larger in holding Harry still. Harry tried to squirm away from the blade, but the men only laughed while they sliced away his clothes.

Harry's face burned in shame as they cut away even his drawers, leaving him utterly bare. He poured as much hatred into his glare at Lucius as he could, wishing looks could kill.

"Scrawny," Lucius tutted. "Really, the savior of the wizarding world, looking like skin and bone? How embarrassing. Clean him and then secure him in the circle."

The snatchers used a few spells to scrub the sweat and dirt from his skin and hair and nails until he was pink. Then they shoved him into the ritual room and forced him into the center of the circle, where he was pushed down until he was laying on his back. Chains sprang up around him, wrapping over his arms and torso and legs so that he couldn't move.

The snatchers left, leaving Harry alone with the two Malfoys staring down at him with identical gray eyes.

"Isn't this an awful lot of work just to kill me?" Harry spat, rattling the chains.

"You called?"

Harry craned his head to look towards the door. He knew from that unmistakable drawl who it was already, but…

"Snape, you betraying bastard!" Harry shouted, renewing his struggles.

Snape raised an elegant eyebrow and then turned to Lucius. "Bellatrix claimed you needed the potion. I see it was not her usual deranged rambling."

"You have it?" Lucius asked.

Snape nodded shortly, withdrawing a vial of pearlescent green liquid from his robes. "He must ingest it first before the ritual can be performed. It cannot be spelled into his stomach, unfortunately. This ritual is meant for willing participants. Thus, the determining potion must be swallowed."

Harry was more confused than ever. He clenched his fists and bucked against his restraints, only certain that whatever happened he couldn't allow them to go through with whatever ritual it was they were planning.

"We will just have to force it down his throat, then," Lucius said. "Draco."

He took the potion from Snape, then crossed to stand over Harry's head. Draco followed a moment later, face carefully blank.

"Would you help hold him still, Severus?" Lucius asked.

"Of course."

Harry met their eyes as they knelt around him, feeling cold metal biting into his skin."Get away from me you perverted -"

Snape gripped Harry's hair and jaw in spidery fingers, forcing his head still. Harry slammed his mouth shut as he saw Lucius lift the vial threateningly, but a moment later, Draco was pinching his nose, stopping Harry from breathing.

Harry struggled, bucking against their grip until he started seeing stars. His mouth popped open before he realized it, and immediately, he tasted something like seaweed and crushed pearls. He gagged and tried to spit, but one of them had already clamped his jaw closed again, trapping the potion inside his mouth. Draco was still pinching his nose, and Harry spent another few moments trying to break free of their hold in vain before he had to swallow or suffocate.

He shuddered as it went down, and the death eaters let go.

The potion coated his throat. He licked the remnants from the insides of his mouth and tried to spit it out, but knew it likely wouldn't make much of a difference. The concoction was sitting in his stomach already, and he had no way to force himself to sick up tied down as he was.

The three men spread out at equal intervals around Harry and began chanting. Harry yanked at his restraints, having no idea what they were trying to accomplish but knowing it couldn't be good. As they continued, he felt magic gathering against his skin and then probing beneath, tickling against the potion sitting in his stomach.

The lines of the ritual circle began to glow sea-green.

Harry's body seemed to ripple. He thrashed, vainly trying to escape the magic churning around and inside him, but the chains held fast. He felt things growing from his arms, from his ears, from his hips. He felt his legs pull together even as they started itching so badly that they felt like they were burning. Even his eyes seemed to come under a strange pressure, his vision wavering and flickering. Lines of pain seared across his ribs. His breaths came shorter and shorter until Harry could no longer feel his chest rising and falling, like lead had been poured into his lungs. Harry clenched his teeth, air stinging his skin, but no tears came to leak from his eyes. Spasms and cramps contorted his body in ways that were not humanly possible, each one producing a shout of pain until finally…

The chanting stopped.

Harry was still. He should be gasping for breath, but his chest felt utterly solid, as if his lungs had been filled with lead. The skin over his ribs was moving, somehow, in a way that reminded him of breathing, but it was all wrong. He wasn't breathing. He felt incredibly dry, as if every bit of water in his body had been sucked out.

He tried to gasp in air, but his mouth opened and his chest remained still and solid, blocked. Little black spots danced in his vision.

"It worked," Draco murmured, sounding shocked.

The air he was trying to breathe rasped in Harry's throat. It stung against his skin as if it was full of minuscule knives. He tried to make a sound, anything to let his captors know he was suffocating, but there wasn't a whit of moisture left in his throat to lubricate his vocal chords. All he managed was a dry, choked rasp that hurt his throat. The black spots were getting bigger.

"It would seem he is in need of water."

Harry saw them standing over him again. Draco's eyes were wide with shock and curiosity, while Lucius had his nose wrinkled as if he'd smelled something unpleasant. Snape appeared bored, though he was the one who'd spoken.

In one last desperate attempt, Harry tried to buck free once more. The chains, however, remained crisscrossing over his body, holding him down. His legs felt wrong: glued together, incredibly heavy, far too long, and bendable in all the wrong places. They felt less like legs and a lot more like his boneless arm after Lockhart had tried to heal him.

He tried again to cry out, to speak. Panic made his thoughts race. The blockage in his chest wasn't shifting, like he'd had the wind knocked out of him, except that moment of relief when his lungs began moving again wasn't coming. The black spots were now blocking out almost half his vision, and the death eaters were still just standing there, watching.

Bellatrix's mad cackle snapped against his ears. "Oh, itsy Potty-fish out of water! Does it hurt, fishy?"

So this was how he'd die. Why hadn't they just cast an Avada Kedavra?

Snape pointed his wand down towards Harry's chest and drawled words Harry didn't truly hear. A wide jet of water shot out of the tip of Snape's wand, washing over Harry's body and instantly drenching him. Harry tasted salt as the water flooded into his mouth and nose, and spluttered, his panic growing. Snape was trying to drown him, he…

The spinning, the black spots, started to fade. The moisture pouring into the orifices of his face eased the fierce stinging. Rather than drowning him, the water seemed to bring relief.

His lungs still wouldn't move, but the movements in the skin on his sides seemed to intensify. Harry lay under the jet, stunned, not breathing, yet no longer suffocating.

"We should move him before the water ruins the hardwood outside," Lucius drawled. "Narcissa would be most displeased."

"Quite," Snape agreed. Harry couldn't see them through the deluge of water pouring over him. "This will also not keep him breathing indefinitely. He needs to be submerged. I trust you have an appropriate tank prepared?"

"In the cellar," Draco volunteered.

"Let us waste no more time, then," Snape said. "Best not to risk killing our Lord's new… pet."

Harry had recovered enough that he merely felt woozy, the black spots faded to pinpricks, but he still didn't feel right. The chains gripping him clacked and chimed as they withdrew, and he kicked out, trying to swipe Snape's legs from under him. Harry's own legs bent nauseatingly, their weight keeping them close to the floor as they slid over the marble as if it had been greased. He didn't feel them connect, but the movement made his head spin and his stomach flip.

A rough net appeared and wrapped itself around him before Harry could try anything else. It pulled his legs back straight and stuck his arms against his sides, then lifted him into the air. His head dangled off the edge of it, tipped back.

The spray of water stopped. Harry jerked against the net as the air seemed to knife into his body with renewed vitriol, clawing at raw insides and dry eyes and throat.

Bellatrix giggled as Harry squirmed, bobbing into his field of vision as she came to stroke her pointed nail down the side of his face.

"So much better," she crooned.

His mouth was open in a futile attempt to draw air in, making patheticly rasping, choked noises. The black spots were growing in his eyes again, his lungs still frozen solid. His head spun from lack of oxygen. He wanted the water back, and couldn't understand why.

Halls passed in a blur of dark wood, silver-gilded wallpaper, and sneering blond portraits. Somewhere, a woman was screaming. The sound tore at Harry's heart, and he jerked in the suspended net, a panicked thought of Hermione flashing through his mind.

Bellatrix laughed in glee. "I'll come visit later, little fishy. I'm going to go pay your mudblood friend a visit."

She bobbed away. Harry thrashed in the net, air scratching his throat as he tried to shout after her. Through what remained of his vision, he saw paneled walls continuing to move past.

They passed under an archway and down a staircase. A door creaked heavily, and they passed through a pool of flickering firelight into a large, dark space. Harry couldn't tell if it was so dark because of the lighting or because he was finally blacking out.

Suddenly, he dropped.

Water surged up and around him with an almighty splash. Harry's eyes shot open in panic, his heart suddenly beating rapidly once again, adrenaline flushing out the symptoms of suffocation he'd been paralyzed by. He sunk straight to the bottom and bumped against a smooth floor, where he thrashed in the nets that still wrapped around him.

They'd decided to well and truly drown him now?!

He felt the water racing to fill all the openings in his body, filling up his throat and his nose, rushing in his ears. He tasted overpowering salt. He caught a glimpse of glass, of the silvery disturbed surface of the water, and of black scales. He shouted, bubbles rushing from his mouth, but he couldn't swim up to the surface to escape from whatever it was they'd tossed him into this tank with.

"Calm yourself, Potter," Snape sneered from up above, his form wavering through the sloshing water. "Are you truly imbecilic enough to think that you will drown?"

Harry expected himself to begin passing out any moment now, but gradually stilled as he realized that the water reaching into him didn't feel suffocating. It was swirling into him and under the surface of his skin in a strangely enlivening current. The black spots had almost faded to nothing, and he didn't feel the need to gasp for breath any longer.

He still couldn't breathe, yet somehow, he was no longer asphyxiating.

"What?" he found himself asking, his voice coming out as a high-pitched squeal that had more in common with a dolphin's sound than human speech. He flinched in response as it echoed in the water around him, and attempted once again to free himself from the stranglehold of the netting. It was pointless. The more he thrashed, the tighter the ropes seemed to constrict around him. He could hardly flex his body at all now.

He fell still, laying under several feet of water, utterly confused and stunned by panic.

"Perhaps being trussed will prevent you from further stupidity, but I admit that I am not naive enough to think you will find a way to endanger yourself regardless," Snape sneered. "So, for your simple mind, do not leave the water. I trust even your sluggish faculties will work out why in time."

Snape whirled and strode away, robes billowing just the same way they did at Hogwarts. Harry shouted after him, the sound rippling as a horrendous screech through the water. If they could hear him, it was ignored. Harry could just see Snape join the Malfoys, framed in light from a doorway some distance away, before the door slammed shut. The room became dark, lit by a single torch hidden by one of many pillars.

"Hello, Harry."

Harry jerked, still thoroughly trapped by the nets, to look up above his head. Luna's wide, mirror-like eyes peered down at him, completely serene. Her words had been a little blurred by the effects of the water between them, but he understood her just the same.

She'd been missing for at least a month. Was this where she'd been the whole time?

"Luna?" he asked. Underwater, it didn't hurt to try to talk, but his voice still sounded foreign. High, echoing, and oddly… melodic.

"I didn't realize you were a merman, Harry," Luna said, blinking as if accusing him of forgetting to tell her his birthday. The words made him freeze. "You have a lovely tail."