Harry's mouth opened in bewilderment, staring at Luna, before he thrashed in an attempt to lever himself upright to see his own body. He only managed to catch a glimpse of a long, black tail before the netting pushed him down again.

Bloody hell.

"You won't drown me, I think. I'll help you, Harry."

Harry frowned through the glass as Luna kicked off her filthy mary-janes and grimy socks. She was wearing denim overalls that had once likely been very colorful from decorative embroidery, but now were ripped and brown. The edge of the tank was as high as her waist. As he watched, she put her hands on the edge and pushed herself up on straining arms, wrestling a leg over the edge.

"Wait, Luna - "

Luna hesitated, blinking at him, then smiled.

"Oh, you have a lovely voice," she said. "I can't understand you of course, but I've heard it's possible if I stick my head in. Hold on."

Then she dropped her legs into the water right next to his hips, sending water splashing over the edge of the tank and dirt clouding into the water.

Harry really couldn't do anything as she took in a deep breath and then submerged into the tank with him. Her eyes were slightly glazed, as usual, seeming to look straight through the tangled webbing wrapped around him. Her fingers were deft, though, flitting over rope as she tugged lightly on different strands, trying to find where it could be pulled free.

"Luna?" Harry tried again, quieter this time, watching her work.

She stood back up, putting her head above water so she could take a deep breath.

"So it is true that you can understand mer underwater," she said, smiling dreamily at him. "Don't worry Harry, I'll get you free."

She ducked back under, moving further down his body. In another few seconds Harry felt the ropes around his legs - his tail, oh Merlin - loosen. Luna went back to the surface for air again.

"Your fins are quite sharp," she said placidly. "They've already cut through the ropes in several places. It's just tangled, is all."

Then she was back under, tugging him carefully free again.

Harry was desperately trying to get his thoughts in order.

"Fins?" he managed, the simple word sounding less like the panicked squeak he'd imagined and more like a swooping note. The netting drifted away from his body where he should have had knees, the ropes cut. He felt some part of himself spring free as the pressure loosened.

Luna went back to the surface to move another few feet down. "Of course, Harry. Did you not know you were from the deep?"

"No," Harry said, and it sounded almost like one of the mournful humpback whale cries that sometimes played as part of Aunt Petunia's "Oceanic Ambiance" music. He swallowed, feeling the water swish in his mouth and throat. I'm a merman. A… a bloody fish! I'm breathing in water, for Merlin's sake, and I sound like a whale!

When Luna went up for air again, she gave Harry a bright smile.

"It's alright, Harry," she said placidly. "I'm sure lots of people don't notice that they're sea-people at first."

Her next trip down freed his le… tail. Harry wriggled, trying to push himself up to see, and caught a glimpse of a large greenish fluke flash through the water at the other end of the tank. Luna hopped up onto the edge of the tank as he moved, lifting her feet far up away from him.

"Did you forget that your fins are sharp, Harry?" she asked curiously.

"Sorry," Harry said, the simple word guilt laden. She likely didn't understand the words, since she was still above water, but she still smiled as if she understood.

There was only a small amount of netting left tangled around his torso. It was stuck on something on his back, but Harry was able to loosen it enough that he was finally able to plant his hands against the bottom of the tank and push himself up to look down the length of his body.

Merlin, it's true.

Sinuous and snake-like, coated in scintillating layers of black and green scales glinting dully in the dim firelight of the cellar, Harry's tail extended almost ten feet past his torso. Translucent, delicate green fins with bony spines fanned out in sharp ridges over each hip before tapering into thin razors towards the tip of the tail. The fin at the end was similarly translucent and ribbed with black, bony spines, with a deep "v" cutting into its center. The edge was frilled with more flexible bits of fin, allowing the very tip of his tail to look like a ruffle of silky green fabric fluttering in the scant current of the tank. Harry flexed his "toes" and saw his flukes expand and contract in response, like a fan opening and closing. Clenching his muscles made the fins down his sides stand up straighter, drawing the edges tighter into a knife-edge. Forcing himself to relax let the fins lay down passively against his sides.

Harry twisted, pushing himself against a glass corner, and wrestled with the remaining bits of netting. He was able to push it up over his head and then pull it free from his back. That done, he discovered what it had been stuck on: he could feel a large, stiff fin running down his spine as it flexed against the wall. It collapsed downwards as he shifted, falling flush against his spine and underneath his hips.

Heart beating rapidly, Harry ran his hands down his chest, feeling the strange slickness of his skin and finally noticing the light patterning of pearlescent green scales laying over his still (mostly) skin-colored torso and arms. Pale green gave way to dark green and then to black between his waist and hips. Delicate, frilly-looking fins like the ones at the very tip of his tail edged the outside of his arms; and there was a small amount of webbing stretched between his fingers, which were now tipped in dark green and had pointed nails. Gills, appearing like rows of open gashes in the skin over his ribs down his sides, opened and closed rhythmically to expose bright red flesh inside. He had ceased panicking over the still solidness of his chest, now that he wasn't suffocating, but realizing that it was because he didn't have lungs anymore was still a numbing thought.

Any body hair he'd had was gone, though he could still feel the hair on his head tickling his ears and forehead and neck. His ears, he found quickly, had become spiny, fanned fins on either side of his head with a small hole where a wider ear canal used to be. His eyebrows and eyelashes were gone, though blinking caused a transparent lid to close over his eyes. Thankfully, when he tried to close them, an opaque eyelid slid into place to block out the dim light.

His privates seemed to have disappeared somewhere into his tail, though with Luna watching calmly, he couldn't feel around to find out exactly where.

His eyes finally tracked back over to the girl, who looked so frail covered in grime from her imprisonment and soaked from her expedition into the tank, yet seemed as if nothing more interesting than breakfast had occurred. He opened his mouth – to say what, he didn't know, because his mind had fallen completely blank – and then shut it again, staring at her.

Luna swung her feet slowly through the water above him, humming. Dirt from her clothes had clouded the water, but he could still discern her cocked head as she studied him. "Don't worry, Harry. You're just as handsome as you were before."

"I'm not…" his voice vibrated in the water, completely foreign, more at home in some fake oceanic piano soundtrack than a conversation. He let his voice die and swallowed again, a distinctly strange sensation when his mouth was constantly filled with water. Maybe…

He squirmed so he was more or less leaning into the corner of the tank, then reached a hand up to grasp the edge so he could lever his head and shoulders out of the water.

The air stung just as much as it had before. Harry blinked his new transparent eyelids closed, which created a barrier between his sensitive eyes and the harsh dryness of the air. There was nothing to be done for the way it prickled against his skin and the rasp of it in his draining sinuses and mouth, though.

"Thank you," he tried, only to wince at the abrupt chalkboard-like screeching that came from his mouth. It sounded like… bugger, like the awful noise that had come from the golden egg until he'd put it under water. Luna didn't even wince, though she cocked her head as he sank shame-faced back under the water.

"Are you embarrassed, Harry?" she asked. "It's quite alright, you know. Most mer can't speak human languages, so it's perfectly natural. I'll get back in. Just be careful with your fins, Harry."

Harry nodded and used his arms to push himself awkwardly into a corner. He had to jam his tail against the opposite wall to keep himself from sliding down. His body wasn't slimy, a small relief, but it was slick.

I'm a bloody merman!

Hysteria bubbled in his throat. He brushed his hands over his body again and flexed his fingers, trying to steady himself through familiar movements while ignoring the strange flex of muscles that used to be legs. Despite his efforts, his eyes were drawn back down his body to the length of his tail, which caught the dim light to show barely discernible, mottled patterns of deep green and copper amidst the black. He would have said it was pretty if it wasn't his own body he was staring at.

Luna dropped back into the tank and stepped over Harry's tail, movements slowed by the drag of the water. As she chattered, she took up a position behind the curve of it, her back to the wall the tank had been set against. "I've never spoken to a mer before. I tried talking to the tribe in the Black Lake, but they didn't understand English. Dumbledore said if I want to I can learn Mermish, but I probably won't be able to speak it for another ninety years or so." She smiled brightly, eyes passing over his, then crouched into the water so it covered her head. Her long, silvery hair fanned out around her, catching the dim light so it shone white.

"Thank you, Luna," Harry said (sang?) sincerely. He tried to stop thinking about his tail and focus on the scrape now visible on her temple and the tears in her clothes. "They've hurt you. Are you alright? Why are you here?"

His worried tone seemed to translate into notes that were somehow anxious and mournful. Besides the school song, Harry had never sung a thing in his life. There was no way a few simple sentences should sound so… beautifully haunting.

Luna pushed back up into the air so she could answer. "Oh, I'm alright. The nargles came for me hoping daddy would stop writing about them, but I know he won't sacrifice the truth for anything, so it's quite alright, really."

Harry swallowed, unsure how to respond. When she ducked her head back under, though, he made himself say something so she wasn't wasting her breath.

"I'm sorry."

"I'm fine, really," she said with a vacant smile. "It is nice to have someone to talk to now, though. I was getting quite lonely."

"Oh Merlin, have you seen Hermione and Ron?" Harry asked, hardly remembering to wait for her to duck under the surface. He jerked, only stopping himself from knocking his tail against Luna's ankles with a last-minute thought. Last he'd seen them, they'd been getting dragged away to a cellar. This cellar? Where were they? He thought he'd heard Hermione screaming -

"Oh yes," Luna said in response, nodding serenely. "I don't have my spectrespecs, but I suspect they're both infested with wrackspurts, like you. I wasn't sure if wrackspurts would be attracted to other species or not, but I suppose if they're in your head then they must be. There are quite a lot of them around here, though. Fortunately, the death eaters let me keep my bracelet when I explained what it was for, which was very kind of them, really, so I'm sure I'll be alright." As she spoke, she twisted a bracelet braided from leather and wet plant material of some sort around her wrist. "Would you like to wear it for a little bit, Harry? It can help you feel less fuzzy."

"Thanks, but I'm alright, I think," Harry said when she ducked back under. "Maybe try not to get that wet. Luna, where did they take Ron and Hermione?"

"Perhaps you're right." Luna's gaze grew more distant, aimed at the wall behind the tank, but she continued to twist the bracelet around her wrist. "I don't know where they went. The nargles came for them just before you came. I don't think they had any charms to protect them, and I lost my necklace back at home, so I couldn't help."

Harry shuddered, remembering Bellatrix's taunting words as he'd been carted through the halls. His friends were being tortured, he was sure, and he was stuck here in a bloody fish tank.

"Try to ignore the wrackspurts, Harry," Luna advised sagely. "The nargles have always brought me back here after taking me away."

Harry closed his eyes, a sick feeling in his gut as he realized that Luna – innocent, harmless Luna - had been tortured too.

"I'm so sorry, Luna," he said. This melody sounded haunted but broken. No matter what he said, he couldn't make it sound normal.

"It isn't your fault, Harry," Luna said with a soft, absent smile. "You're very kind, though. You know, your voice really is beautiful, though very sad. I've heard that music can keep wrackspurts away too, but I've never been very good at singing. If I had a voice like that I don't think I'd stop."

"I never have either," Harry said… sang. "The… the death eaters turned me into this, Luna. Right before bringing me here."

"Oh, well that makes sense then," she said. "I've always wondered what it would be like to be something else, you know, and the mer are quite an interesting race."

Her nonchalance was suddenly grating instead of comforting, and the hysteria he'd pushed away bubbled back to the surface. His words came out staccato; frenetic; discordant. "Luna, I'm a bloody fish!"

He regretted his tone as soon as it came out, but Luna seemed unbothered. She only gave him a kind smile, her eyes skimming over the top of his head.

"Oh, you're not a fish, Harry. You're far smarter than they are, and I don't think fish sing. Besides, I've never seen a fish infested with wrackspurts." She giggled, a frail hand moving over her mouth. "Are you sure you don't want to borrow my bracelet, Harry?"

"No, thank you," he said, quiet. "What am I, exactly, then?" He remembered the merpeople from the Black Lake. They were smaller, and entirely gray or green, with kelp-like hair and yellow, slitted eyes. He couldn't be sure about the eyes, but he was pretty sure he looked entirely different in every other way. "I don't look like the mer I've seen before."

"Oh, that's because you've only met the freshwater tribes," Luna said, her face lighting up. Her tone was the same as when she talked about Crumple-Horned Snorkacks and the Rotfang Conspiracy. Harry wasn't sure if that was a good or a bad thing yet. "I've never met a member of the deepwater clans until now, either, but I've heard descriptions. It's quite an honor, Harry. I'm very happy to be your friend so long as you still want to be mine. I understand the clans are very reclusive."

Well, that sort of answered the question, and it made sense when he remembered the salt he kept tasting in the water. Whatever kind of mer he was lived in the ocean, though Luna seemed to have forgotten that he'd only been changed into this recently.

"Of course we're still friends, Luna."

Her eyes slid over his, but she beamed at this proclamation: a smile brighter than any mythical creature or conspiracy theory could give her. Harry managed to return it shakily, recognizing that she'd been all alone to handle being kidnapped and tortured for a month, yet her first thoughts had been to free Harry from the net and offer him a protective charm. She deserved so much more in a friend.

…Such as the ability to get up and fight his way out of here so they could all escape.

I'll go back to normal eventually, he thought quickly, thinking of the gillyweed. It's just temporary.

Okay, so he was still freaked out.

What if it isn't? Why would they go through all the effort of that ritual just to make you sit in a tank for a few hours? If they'd wanted to torture you, a crucio or a suffocation curse would have served just as well.

The Hermione-like voice named his fears so accurately that he had to shove it away to keep himself from dissolving into panic again.

He refused to think about it any longer. He would revert back to normal, given some time, and Ron and Hermione would be alright. They'd fight their way out together and bring Luna with them.

He would change back.

He had to.


A/N: Luna is precious and I love her. I was very happy to write an entire chapter between her and Harry because her reactions are just so entirely unique.