“I’ll do it.”
Rarity was surprised at how quickly the words came out of her mouth. She hadn’t even given Rainbow much of a chance to think it over or even volunteer for it. Rarity didn’t even particularly know why she was so quick to volunteer. Maybe it was just her generous side, but she didn’t want to risk endangering Rainbow’s hopes and dreams if the worst came to pass—that Melody was right, and she wouldn’t be able to undo the spell and change her back to normal. With her scars and wounds, Rarity already knew her image would be ruined in the fashion world. Being a siren couldn’t possibly be any worse. And besides, it wasn’t like she needed to be pony sized to work on pony dresses. It would just be a bit harder, but nothing she couldn’t overcome.
And of course, just like she had expected herself to volunteer without hesitation, she wasn't surprised when Rainbow immediately rebuffed her with an emphatic shake of her head. “No way, Rares,” Rainbow said. “It’s too dangerous.”
“Dangerous as it may be, I don’t think we are in much position to complain,” Rarity said. “We need to do this, and I’m the best candidate for it.”
“You’ve already done enough for us, Rares,” Rainbow insisted. “You survived that whole ordeal at the temple alone, you barely made it out of there with your life, you even found the unicorn figurine and this weird siren heartstone thing—you deserve a break. Let me handle it!”
“While I appreciate your bravado in volunteering yourself for this, I think I should be the one to do it,” Rarity said. “We lose less if I’m the one who does this and ends up stuck as a siren.”
“Lose less?” Rainbow frowned at Rarity. “What about your magic? You can teleport and do so much crazy stuff! I can only fly around, and not even all that well right now with my wing still only just healed!”
“Your ‘not that well’ is still much better than every other pegasus here,” Rarity said. “What few of you are even still alive, I might add. How many pegasi do we have at the camp still? I don’t think we could afford to lose a set of wings, not while we still have plenty of unicorns.”
“There’s still three of us,” Rainbow said. “Me, Stargazer, and one of the pirates. But sirens can fly, too! I wouldn’t lose that!” She blinked. "Oh, and Champagne, too. Nearly forgot about her."
“Then think of it as me gaining the ability to fly,” Rarity said. “In addition to siren song to augment my own magic. I think singing is more my forte than it is yours, anyway. It’s empirically the better choice to have me do this.”
Rainbow gnashed her teeth together in frustration. “I just… I just don’t want to see you stuck like that,” she said. “Stuck as a big scaly fish dragon thing… forever! I know how much you care about your appearance, Rarity. I can’t imagine what that would do to you, even if you want to pretend you’re fine with it.”
Rarity hesitated at the accusation; Rainbow was right, after all. Vanity was one of her weaknesses, and she didn’t know what she’d do if she found herself stuck in the form of a big sea monster. But at the very least, sirens were beautiful in their own ways, and everything they did exuded grace and power in equal measure. That was one way to make up for no longer being Equestria’s most beautiful mare, right?
“My career wouldn’t end if I were to be stuck a siren,” Rarity said. “I can still make dresses, though I’d have to make some appropriate accommodations. You, on the other hoof, would never be able to work at the CWC or fly with the Wonderbolts ever again. I couldn’t make you give that up for me.”
Rainbow winced and discreetly glanced at her wings. Rarity knew she was weighing a life without them in exchange for taking the spell for her. Still, her heart did momentarily swell when Rainbow grimaced and again shook her head. “I’d give it all up for you, Rares.”
“While I’m glad to hear that, the matter has already been decided,” Rarity said. “It is better in all respects if I take this instead of you. Forgive me if I same brash or rude, but I shan’t hear another word of protest from you on the subject.”
The pegasus sighed and quite literally came back down to earth. She landed in front of Rarity and looked the unicorn up and down. “I just… don’t want to lose you again. Not after all this.”
“You won’t lose me,” Rarity said, stroking Rainbow’s cheek. “Melody will keep me more than safe down there. I mean, have you seen how big she is? The safest place on the entire island chain is by her side. I won’t have anything to worry about.”
Though Rainbow quite obviously wasn’t convinced, she finally began to relent in the face of Rarity’s persistence. She slowly shook her head and pressed her cheek against Rarity’s for a brief moment. “It’ll be a lot harder to have sex when you’re a giant fish,” she said.
Rarity giggled and let her eyes close. “It depends on how adventurous you feel,” she said. “I’m sure we could figure something out.”
“I don’t even want to start looking at the specifics of that,” Rainbow said. “Especially if sirens like, y’know… lay eggs and stuff like other fish.”
“I’m sure if we asked Melody, she’d give us an answer.” Rarity stepped away from Rainbow and quickly pecked her on the nose. “It’ll be fine, darling. I’m sure of it.”
“I’m not so sure… but if we don’t have a choice.” She kissed Rarity back, and then enveloped her in a feathery hug. “Just… come back to me, you pretty, pretty pony.”
“You can count on it,” Rarity assured her. “And besides, if worst comes to worst, I’m sure Twilight will figure out some way to change me back. We can always count on her.”
“That we can.” With another weary sigh, Rainbow sat down next to the water, her wings gently urging Rarity down with her. “Just try not to freak out too much when you have to eat fish. Sirens don’t eat plants.”
Rarity felt her stomach begin to flip when Rainbow said that, and she briefly shuddered against the pegasus’ side. “I… suppose that’s something I’ll have to get used to.”
“Better get used to it quick, then,” Rainbow said, noting the churning of the water. “She’s coming back.”
Within a few seconds, Melody’s translucent green fins broke the surface of the water, followed by the siren’s scaly body not too long after. Once more, after taking a second to adjust to the different environment, Melody quickly spotted the two ponies and repositioned herself so she wasn’t towering over them. “Well, I’ve got it,” she said, lifting up the heartstone, which looked so impossibly tiny in her hooves. “It still has just enough magic left in it that I could probably make something work from it. This was from a very young siren, judging by the size. Much younger than me.”
She set the gem down on the stone next to the two ponies, and Rainbow raised her eyebrow at it. “Why is it green?” she asked. “I thought, like, all sirens’ stones were red.”
“No?” Melody’s brows dropped in confusion. “My stone’s green. Some sirens have red stones, some have blue stones, some are yellow. It depends on what kind of emotion we draw our magic from. Red is anger and conflict, yellow is happiness and joy, you know.”
“Then what’s green?” Rarity asked. “Jealousy?”
“No. Jealousy is really hard to foster in a song. I wouldn’t be able to collect a lot of magic if it was jealousy. No, green is… green is loneliness.” Melody seemed to deflate as she said those words. “It’s… the irony is not lost on me. Trust me. That’s why all my songs are sad and sympathetic. They make creatures long for companionship, to go back home, to find happiness again. It’s a very bittersweet taste.”
Rarity remembered how miserable Melody’s songs had first made her when she heard them so long ago. She’d had terrible dreams of homesickness and loneliness, and the next morning, she’d been utterly drained. At least now it all made some sense. “I’m… sorry to hear that, Melody.”
“It is what it is, I guess.” Shrugging, she vigorously shook her body as if she was trying to scatter away those emotions. “So, did the two of you figure out who gets to be the lucky pony?”
Rainbow immediately shot Rarity a look. “Are you sure about this, Rares?”
“No, but I’m going to do it, anyway.” Standing up, she gently shed Rainbow’s wing from her back and paused to passionately kiss her marefriend. When they broke off, she turned her attention back to Melody and nodded. “I’m going to do it," she repeated.
Melody slowly nodded her head. “Somehow I knew it would be you. That’s good; I can already tell that you’re more agreeable to song. That’s an important part of being a siren.”
“That’s an understatement,” Rainbow huffed.
Melody only shot the pegasus a glance before her focus shifted back to Rarity. “I think I’ve figured out the notes to make this work. All you need to do is hold the stone to your chest and keep it there. Just let me know when you’re ready.”
Rarity took a deep breath to steady her trembling limbs. She’d already done this once before, technically; amazingly enough, the feeling of losing two of her limbs into her tail wouldn’t be that alien to her. She’d just be much… bigger, and infinitely more carnivorous. Those were all things she could get used to without too much fuss, right?
“Do it now before I change my mind,” Rarity said. “The faster we get this over with, the better.”
Melody nodded, and she gestured to Rainbow Dash. “You’re gonna want to make some space,” she said. “Sirens are… not as small as ponies.”
Rainbow Dash shot Rarity a smile and a nervous wink. “Good luck, Rares. You’ll be the prettiest siren ever, I know it.”
“Thank you for the words of encouragement,” Rarity said, watching Rainbow backtrot to safety. Then, holding the heartstone close to her chest, she closed her eyes and deeply inhaled. “Let’s begin.”
Melody nodded once, and after a moment to fill her enormous lungs with air, she began to sing. The notes were low, long, and soft, almost like a deeply strung cello echoing in the cavern. As the notes persisted, they made Rarity’s skin itch, and she suddenly became overwhelmed with the feeling that everything about her body was wrong, There was no better way to describe it; if she wasn’t trying to hold still for Melody’s song, she felt like she’d start clawing her skin off with her hooves just to break out of her shell, like an insect shedding is exoskeleton.
The meter and notes of Melody’s song slowly began to increase in speed and pitch, and every single utterance out of the siren’s beak felt like it rewrote some part of Rarity’s being. The more she sang, the more Rarity felt an energy building up inside of her, just waiting to break free. The mounting pressure in her skull made her want to scream, and it took all of her willpower not to just blindly take off, fleeing away from the song that wounded her so.
A dash of high notes that jumped several octaves up the scale made Rarity cry out in pain. She could feel the heartstone she held to her chest glowing hotter, like it was made of fire, a fire that soon began to sear its way into her ribcage. When Rarity opened her eyes, she saw the heartstone wasn’t so much held by her hooves anymore as it was melding into her chest. Adrenaline began to race through her veins, and she shot Rainbow Dash a look of worry and regret as Melody’s song began to crescendo.
As soon as the heartstone bonded itself to her flesh, an overwhelming volume of changes began to strike Rarity all at once. Her teeth sharpened inside her lengthening and hardening muzzle, and when she tried to clutch at the beak forming around her nose and lips, her hooves had cleaved themselves down the middle. Coat hairs turned to milky opal scales, and her horn loosened and lengthened, becoming a wavy pair of antennae sprouting from her forehead. The hues and colors of the world seemed to shift and sharpen as an itchiness spread over her eyes, and when she inhaled, the scent of fish and the smells of the cavern were suddenly nearly overpowering. Her remaining ear rose higher on her head, becoming longer and narrower, and her hearing suddenly became crystal clear, like her entire pony life, she’d been listening to the world through a thick oaken door.
The unsettling changes rapidly spread down her body. All across her figure, her coat turned into rows upon rows of thick scales, protecting the soft flesh underneath, and fins sprouted out of her back and along her forelegs. Her spine seemed to snap and stiffen as Melody’s magic worked on it in the feverish pitch of the song, and her flesh crawled as muscles rearranged themselves to more easily benefit an undulating, swimming motion. Her hind legs felt like somepony had grabbed onto the hooves and pulled them back, knotting them into the hairs of her tail before lengthening the entire thing. Bit by bit, flesh and bone and muscle fused together into one strong tail, and what remained of her hooves fanned out into the fin at the end.
A feeling of vertigo overtook her, and between her dazed glances around the room, Rarity felt her perspective changing. Everything seemed to fall away from her, except for Melody, who she seemed to be traveling up towards. Her newly cleft hooves slid about on the stones as she struggled to balance herself, and her uncoiling tail slapped against the stone wall behind her. Eight lines of white hot pain opened up on her neck, four on either side, and they momentarily opened when she gasped as her gills formed. She could feel her voice box strengthening, growing larger and more settled in her expanded throat, and when she squeaked and grunted, it turned those noises into nearly melodious tones.
And then Melody’s song ended on a final crescendo. Silence filled the cavern, save for the ringing in Rarity’s skull, but that too faded in time. Bit by bit, Rarity was able to stay her swaying body and even open her eyes, as different as the world seemed through them.
The first thing she noticed was that she was almost on eye level with Melody. The siren smiled softly at her, and draconian eyes flitted up and down her figure. “I… think that worked perfectly, actually,” she said. “How are you feeling?”
“Like… like I just spent a week in a washing machine,” Rarity said. Even speaking felt wrong with her new tongue and teeth. She couldn’t stop feeling around the inside of her mouth… beak? She couldn’t really tell where the distinction between the two parts began. Closer to her neck, she had lips she could easily move, but they turned into a hardened, solid piece near her nose. She couldn’t even flare her nostrils anymore; they’d been drilled into the hard frame of her beak, completely immobilized.
“I’d imagine that it’s disorienting,” Melody said, trying to assure her. “Just take some time to get used to it. We’re in no hurry.”
“Right…” Rarity carefully shifted her new body around, feeling her strong forelegs and tail move her around on the stones. She already knew it was going to take some time to get used to her new form, though if Melody’s worries were true, then time wouldn’t be a problem at all.
Instead, she turned her head to the side and blinked at Rainbow, who was staring up at her with her mouth hung agape. “How do I look, Rainbow?”
Rainbow blinked. “You’re… wow.”
Melody giggled. “I’d take that as a compliment.”
“I think I will,” Rarity said, shaking her head. “I think I will.”