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2026-08-09
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Hidden Depths

Summary:

In the coastal town of Purgatory, everyone knows the mythology of the Seven Deadly Sins - seven ocean deities bound to the watery abyss, ruled by the Sin of Pride. And of course, everyone knows that Lucifer is the worst of them all, even if no one can quite agree on what he looks like.

Alastor Boudreaux, Purgatory’s politest radio host with a side gig in murder, is more than irritated when a strange mermaid follows him home after disposing of a body doesn’t go as planned. He’s even more annoyed to find that this creature is supposedly the Herald of Lucifer, a being as old as the Sins themselves, but the sugar on the cream is that the blasted thing is determined to be friends with him.

As for Lucifer, well, he’s having a great time with his new best friend. As long as Alastor doesn’t find out who he is, and as long as Lucifer doesn’t fall in love, everything’s going to be fine.

Right?

Notes:

Thanks as always to my lovely beta readers puff, Joules, and Grelly!

A massive thank you to the artists! I had the absolute pleasure of working with elkaseltzer and Froggy for this year's CherriBang, and was absolutely blown away by their wonderful art! Please go check them both out!

 

This has been such a lovely project to be part of - CherriBang is a wonderful community and I highly recommend you come join us next year!

Chapter 1: I'm Alive - ELO

Chapter Text

In the deep, deep waters, where no human could ever hope to reach, there were seven of them. Stories and myths surrounded them, half-truths, rumours, and whispers, the idea of them igniting creative minds again and again over the centuries. Seven immortal beings, hidden beneath the waves, just out of reach. Their names, forms, and purpose varied for the most part, but everyone agreed that there were seven, and the oldest amongst them was the most fearsome of them all, something divine that had fallen from the sky at the beginning of the world into the deepest abyss.



Asmodeus, with his siren song that lured sailors to their doom. Satan, his wrath bringing storms onto clear skies. Mammon, whose whirlpools sucked ships greedily under the waves, never to be seen again. Beelzebub, who controlled the winds, and who would grant you fair passage if you sent her an offering of food before your journey, and rob your vessel of any movement should you fail to appease her. Leviathan, whose two heads could engulf any vessel should her eyes land upon it. Belphegor, whose mists would roll in, hiding sharp rocks and ice and thickening until you could barely see the ropes under your hands.



And Lucifer, their king, the oldest. No one could quite agree what malady should fall under his jurisdiction, but they did blame him for it anyway. If the food turned bad, Lucifer had gotten into it. If a board was found rotten, or the ship was taking on water, well, it was Lucifer’s doing. Anything and everything that didn’t fall under his siblings, Lucifer was given by the cursing of sailors and the weeping of mourners. His name rang like a clear bell in port towns, endlessly repeated with scowls and sighs. His form was painted, time and again, a hulking horned figure with snarling teeth, towering over the other Sins like one of his brother’s storm clouds. Everyone seemed to agree that he ought to be impressive, horrifying, and handsome, though perhaps that had more to do with the artists and their own fantasies.



Certainly, it was no surprise that Alastor Boudreaux did not recognise exactly who stumbled upon his boat one foggy night.



* * *





Alastor was, to the bustling town of Purgatory, a pillar of the community. A charming and polite bachelor, with a handsome face and a winning smile, living in a cottage just on the outskirts. He opened doors for ladies, brought home cooked meals to sick grandmothers, and ran a radio broadcast that the people of the town, young and old alike, tuned into almost religiously. On the waves, such broadcasts were unfailingly reliable, and he happily passed on messages between family and the fishing boats, wishing children good night from their parents on the ocean, or vice versa, in between music that never failed to lift the spirits.



He was also quite a successful murderer.



That part, of course, was not public knowledge. To the townsfolk, Alastor was a sweet young man who lived alone, politely rebuffing any attempts to get him married into their families. Besides, it was a coastal town, and people did tend to go missing from time to time. No one would have dreamed of connecting the occasional disappearances to the charismatic radio host whose voice bridged the gap between land and sea.

 

And it wasn’t as if Alastor could take all the credit for everyone who vanished into the ether. They just simply went missing...more, when Alastor went hunting, as he preferred to think about it. And truly, he was quite skilled at it. He’d been doing this for a decade, as carefully as the day he’d started, and no one was any the wiser.



Until tonight.



He’d rightly been told that the fog would be quite terrible tonight, and headed out with a package to dispose of, with just enough time to get back before it became too thick to see where he was going. Rowing far enough out that he was comfortable in the fog’s cover, Alastor began heaving his cargo to the edge of his little boat. However, as he pushed the neatly wrapped body over the side to join the rest of his quarry in the depths below, just as he might any other time, he turned to find that he had unexpected company. Pale arms were hanging over the side of his little boat, while gold eyes watched him owlishly. 

 

Unsurprisingly, he heaved an oar up and immediately tried to bat the porcelain-pale face away out of shock if nothing else.



“Okay, no--” The person (witness?) let go of the boat, dipping beneath the waves before resurfacing, holding up their hands in a peaceful gesture as they wrinkled their nose. “Could you stop that?”



“Who—” Alastor looked around wildly, trying to spot if there was another boat as the mists sighed over the top of the waves. It would be coming in quickly quite soon, he knew – it was why he’d chosen this night to dispose of the body. Most boats would not risk the sharp rocks in this area on a night where Belphegor reigned, where the faint mists could not be trusted. But if there was no boat, then…



“Would you just put that thing down?” The voice from the water was almost petulant.



Alastor narrowed his eyes as he looked more closely at the person he’d tried very hard to make his second body of the night. Limbs covered in pearlescent scales caught the light of the moon, while soft blonde locks fell around his face, two spots of red like a blush on his cheeks while startlingly ichor eyes looked on Alastor with slight annoyance, eyebrows raised. Fin-like ears twitched, their membrane threaded with gold, whilst red gills sat at his neck and ribs, the same ruby red as the spots on his cheeks.



All in all, clearly not human.



Alastor gripped the oar tighter.



“Sheesh, okay.” Something moved under the water, thrashing lazily back and forth, but the creature in front of him didn’t seem concerned by it even as Alastor’s eyes darted to the movement. “I just wanted to see what you were doing! But fine.



“I didn’t want to be disturbed, thank you,” Alastor said, as politely as he could manage. “What are you, then? A siren?”



“Nope, that’s Ozzie’s department. Thanks for the compliment, though!” The man in front of him sunk beneath the waves until only his head remained above the water, those golden eyes locked on Alastor with undeniable interest. “I saw your boat from the rocks over there?” He pointed into the distance, where Alastor could see the sharp circle of stone known locally as the Devil’s Reef. “And you know, a night like this, no one comes out from the town. It’s why I’m out here at all in the first place, and then I could smell the blood.



As he said the words, those pretty ichor eyes shifted, the gold a pinprick in a sudden sea of crimson. Alastor froze up, and the creature in front of him laughed, waving a hand.



“Don’t be so serious, my guy! I don’t bite-- I mean I do, but I’m not going to bite you. But man, you really came out on a night like this to get rid of a body, huh? Is it like a sacrifice or something?”



“No, just disposal.” Alastor lifted his chin high. “Whatever you are, this is none of your business. I suppose I can trust your discretion.”



“Ooh, you’re going to trust me?” The grin he was given was undeniably sharp, shark-like teeth glinting. “Usually, mortals don’t!”



“You’re stuck in the water, I hardly think you’re going to run around telling people what you’ve seen.” Alastor placed the oar back in its rest, taking the other as he began to row away. To his disgruntlement, something long and gold moved just under the water, and the creature began keeping pace with his boat. 

 

So it was his tail moving before, Alastor realised.



“Man, you sure move slow! You should pick up the pace a bit if you don’t want Belphie to wreck you out here.”



“Well, if you hadn’t come along, I might have been halfway home by now,” Alastor gritted out. “As it is, I’ll be lucky to make it back in time.”



“I mean, I could help you…” The strange creature grinned at him again. “If you say the magic word, of course.”



Alastor shot him a look of pure disgust, only to be met with laughter.



“Fine, fine! Just for today, seeing as it’s a little bit my fault, I’ll give you some help! Not many people get that from the Big Boss of the Abyss himself, you know?” The shimmering golden tail flicked back and forth. “But you’re interesting! I want to see you again! So, just this once…”



He grabbed onto the back of Alastor’s boat, and pushed, tail flicking behind him as they began to pick up speed. An unnatural amount of speed, in fact, that had Alastor clutching at the oars for dear life as the creature almost herded the boat towards the coast line, just a little too close to the harbour for Alastor’s liking.



“Not here!” he snapped.



The creature tilted his head in confusion. “Isn’t this where you guys put the boats?”



The idea that this creature knew such a thing without being told was not a comforting one, but Alastor pointed further along the coast that Purgatory called home, choosing not to think about that until he was safe and warm in his cottage.



“Keep...going, there’s a river that goes into the sea, I moor my boat there.” He gestured, trying not to feel like he might throw up as the fast pace resumed, taking him towards the mouth of the river where he’d built a little dock five years ago or so. The fog was beginning to set in, the air turning colder as the creature laughed with delight as they sped along.



“You good from here?” the creature asked brightly.



“...Yes, I should be.” Alastor tried not to shiver as those gold eyes met his own, staring at him again with that undisguised interest. “Why...would you help me?”



“Eh, Belphie says I need to start cleaning up my own messes.” Sharp teeth flashed at him again. “Besides, you’re interesting, I told you. See you soon, okay?”



“No, I don’t think –”



With a flick of his tail, the creature was gone, ripples spreading out from beneath as Alastor was left staring and wondering if he’d just hallucinated some sort of mer-creature, who seemed to have all but vanished. He did not have time to think on it, however, as he needed to get back to the dock and moor up before the fog set in too badly.



It seemed to be worse tonight, he thought, as he tightened the rope, standing on the dock. Lucifer must have a hand in it as well as Belphegor, for if he hadn’t happened across the mer-creature, whatever that thing had been, he would have been lost at the mouth of the river far before he could reach the dock. The fog had thickened quicker than he’d expected, cold and unforgiving as he wrapped his arms around himself. The night chill cut through his sweater as he made his way back towards his cottage from the path between the trees, the lantern in the window shining a paltry light into the night. Why, even if he had kept on schedule, he might have even gone missing himself, sinking to the bottom of the ocean along with the body he’d brought with him. The thought was more than a little sobering.



Even if he did have the creature to thank for his safe return home, the encounter had unnerved him. Just what was he? The thing had insisted he wasn’t a siren, but he certainly had an ethereal beauty. As though Pygmalion had gone a more aquatic route with Galatea, perhaps, and left the marble quality of the skin behind. Alastor’s murderous tendencies had barely merited any comment, and the creature hadn’t even seemed shocked, had called him interesting and said he would see him later. Which put paid to his little night time boat trips, at least until he was sure that thing was gone. No, first, he would need to find out what he was dealing with.



The red eyes flashed in front of his mind again, making him shiver as he unlocked his door and stepped inside. On a cushion next to the empty fireplace, his cat Shadow was curled up, paws twitching in a sleep that was undoubtedly filled with the gleeful murder of vermin.



They truly were two halves of a whole.



Alastor scratched him gently behind the ears, taking his boots off and heading to bed, wrapping up in the mass of blankets that kept out the chill on nights like this. Soon enough, he felt the familiar weight of Shadow’s paws finding a spot just behind his knees, curling up in his usual place as they both closed their eyes and drifted off to sleep.









* * *





Lucifer whirled around, exhilarated, as he thought back to the man he’d met that night. He was so fun, wasn’t he? And handsome, too, if Lucifer was being honest with himself, but he’d never met anyone who dared brave Belphie’s fogs for their own purposes. The scent of blood had cut through the familiar, drowsy smell of the fog, and then, there he was, haughty and resplendent.



It wasn’t the man’s good looks exclusively that had caught his attention, but also the staggering audacity of the guy. His cutting remarks and clear pride had been even more entertaining than the first impression he’d made, delighting Lucifer further. And oh, but the King of the Sins did like things that his brain deemed shiny.



I should give him something as an apology, he thought to himself. After all, the guy had nearly gotten stuck out there because Lucifer distracted him because he distracted Lucifer. Otherwise, he’d probably have been home safe and sound, while Lucifer had continued looking at the stars, feeling homesick and infinitesimally small.



Yeah, an apology gift! That way, he could start this new friendship out right.

 

He flopped back onto the large golden bed in his private quarters, looking upwards to the glass baubles that hung down from the ceiling, casting different coloured lights upon the walls as they swayed in the gentle current. 



He was lost in the thought of what he could gift to him (humans were so tricky in what they did and didn’t like, but this man wasn’t quite like most humans, was he?) when a glow of gold magic lit up around an ornate mirror that hung on the wall. Sighing, he flicked his tail, swimming through it as though the glass were nothing but water.



A cavernous hall awaited his arrival on the other side, its beautiful pillars decorated with lustrous pearls and gems from long-sunken ships. Seven immense mirrors had been embedded into the walls and decorated just as richly, the one he had just come through bordered with golden snakes with ruby eyes. Their collective magic had woven this place, once upon a time, with treasures and sorcery, creating a place that was safe and big enough for all of them, and as always, making him feel small and exposed. At the top of a towering pedestal, a colossal open shell with a soft bed waited, and he swam upwards to curl up there, letting his tail lengthen as he relaxed into more of his true form. Horns pushed from his forehead, long and crimson, as his tail coiled comfortably, allowing him to rest his arms upon it.



Deep amber magic lit up a mirror ringed with a frame of bright coral, a sweet scent drifting through the water. Here was Beelzebub, joyful and breezy as she stepped through the mirror and became larger than life, the mane of colourful sea foam that made up her hair eye-catching as it waved back and forth. Down here in the depths, she glowed brighter than ever, and she waved happily to Lucifer as she took her seat.



Not one to be outdone, Leviathan came forth next through her own opulent mirror that boasted more jewels than the rest, her eel’s body glinting with bioluminescence as one head eyed Beelzebub and the other let her eyes flick over every gem in the room. She’d probably be prying one out of its fixtures to take it back to her hoard later, but no one minded. She’d bring it back the next time they redecorated, anyhow. The first head settled for snapping its jaws in Beelzebub’s direction, while the second head smiled at her, before wrapping her body around a beautiful green podium with a curved top for her to rest her elbows on.



Mammon’s green magic lit up his mirror next as he pushed his way through, his spider-like body covered in spikes and a grin curved like a scythe, taking his place next to Leviathan. He sent a wink her way, flipping a golden shield like a coin through his curved fingers. She watched the movement hungrily, as she always did, and Lucifer knew that when the next stormy season was brought about by his brother, those two would take delight in hunting ships together for the treasures they might find. Well, it was good when they got along, wasn’t it? Better than when they fought over the scraps of their destruction.



The water turned almost uncomfortably warm as red magic flickered like flames in the largest mirror. Satan, austere as he was proud, swam through to tower over them all, molten lava clear in the fissures of his large scales as he took his seat, barely acknowledging Lucifer as he glared at Mammon and Leviathan. He brought with him the scent of something burning acridly, mixing oddly with the sweet scent that surrounded Beelzebub. Lucifer eyed him lazily with his red and gold eyes, wondering if today was the day that his brother might offer a greeting. 



With Satan, too, was the little creature Belphegor had breathed life into, floating next to his lord with his angler lure shining brightly in their hall. His seahorse-like tail was curling and uncurling as he murmured encouragingly to Satan, taking a seat on the ledge next the gigantic chair.



Asmodeus was next to arrive, glowing in bright shades of pink, blue, and purple alternately, in a pulse as gentle as his smile. His strong, navy-blue tail flicked this way and that, taking in his siblings before he took his seat next to Beelzebub, leaning over to whisper something to her as his eyes landed on Mammon and Leviathan. Whatever it was, it made her giggle, hand covering her mouth quickly to stifle the sound as Asmodeus’ gaze drifted to Lucifer, wiggling his claws in a friendly wave.



Lucifer gave him a soft smile in return as a cloud of mist rolled through the water from the last mirror, impossibly so, a purple light forming within it first as Belphegor yawned, pulling herself together into a coherent shape. Her sharp, needle-like teeth were on full display before her fluffy hand covered her mouth, the lure on her head swaying softly as she blinked.



“Punctual as always, Belphie,” Leviathan snarked.



“Oh, shush, I was hard at work.” Belphegor’s form finally coalesced, her lilac and black koi-like pattern pulling itself out of the lavender fog as her neon pink eyes nictated along her neck, glowing as brightly as the lure. Her arms stretched out one by one. “And don’t think I didn’t notice you slithering through my fog again, Luci, dear. Must you play topside when I’m busy?”



“I like to stretch my scales!” He sent her a fond grin. “And you always do such fine work, Belphie. I like to see it.”



She laughed, drifting upwards to cup his face in one of her six hands, the claws as cold as one of her fogs against his cheek. The touch made his eyelids lower and his limbs grow heavy before she pulled away, heading down to the gigantic sea anemone that served as her seat, its lavender tentacles swaying in the quiet current.



“My dear siblings, I am happy to see that you all are well.” Satan drew up to his full height. Ah, so he was taking the lead again. Did Lucifer really need to be here, then?



“Firstly, Beelzebub. It has come to my attention that an ichthyospawn washed up on a beach in California and terrorised the locals while drunk on your fermentation--”



“Hey, that was not my fault!” Beelzebub objects. “I gave some out to Ozzy’s sirens, and one of them threw a bottle of it and then the ichthyospawn drank it!”



Satan snorted, a puff of smoke leaving his nostrils. “Bringing me to my next point. Asmodeus, your sirens have been running about--”



“They have permits!” Asmodeus protested.



“And behaviour conduct limitations, which have not been followed.” Satan’s voice crackled with thunder. “Unless bootlegging items for you is somehow part of that conduct, which I very much doubt it is. I can turn a blind eye to some stuff, but it’s getting excessive, Asmodeus!”



“Okay, that bit is actually my fault,” Beelzebub confessed, guiltily. “They’ve got some really good snacks up there, and the sirens are the only ones who can go on land without causing a scene! My sweet little wind spirits get distracted so easily, and the sirens are so nice--”



“—And they have a good eye for the finer things,” Leviathan cut in.



“I’ll say!” Mammon crowed. “You should see half the shit those scaly little fucks bring me!”



Is there anyone here who hasn’t been using Asmodeus’ sirens to smuggle their own vices?” Satan’s voice boomed.



Belphegor’s eyes cast down demurely, but she didn’t raise her hand. Lucifer didn’t, either, but simply because it was easier than admitting to his brother that he was actually perfectly capable of walking onto land himself and getting what he liked. Lucifer going topside to bathe in the moonlight was one thing, Lucifer spending the day with humans simply because he wanted to was quite another. Satan would have a bigger conniption than usual if he knew.



He’d been doing it on and off for centuries, but recently, he’d been doing it a lot. Humans were just so...creative. They made the most interesting things, and they were full of joy and wonder, and were always coming up with things he never would have thought of. And besides, down here, he was treated with a mixture of reverence and condescension. Even if he was the oldest, Satan tended to act as though he knew what was best for them all, scolding them and herding them back into line. And yeah, someone had to do it, but all of them treated him like he was the youngest, something precious and yet untrustworthy.



And yes, sneaking off might be untrustworthy in a way, but if they actually trusted him, he wouldn’t have to do it in the first place. Besides, none of them could take human form as seamlessly as he could, because they didn’t see the point. They revelled in showing their eldritch nature, and he did understand, but there was something so wonderful about blending in with a crowd, not being placed upon a lonely pillar with a cold crown on his head.



“Right, that’s it. You’re all banned from using the sirens for smuggling for a month.” Satan pinched the bridge of his nose, growling. “I’ll be tightening up the trade restrictions if you don’t cool it. Do you honestly think that humans won’t notice them hauling sacks off to the sea? Co-ordinate your orders and take turns, at the very least!”



“Who gets to go first?” Lucifer asked innocently. Beelzebub snorted, hiding her smile behind her hand as Mammon and Leviathan put a hand up at the same time.



“Of course it should be me!” Mammon snapped at her.



“Oh, please, you’d be happy with anything. I’ll actually get something worth bringing down!” Leviathan snarled at him with her sharper mouth, as her other head glared at him with a pout on her lips.



Mammon scoffed. “Your shit’s tacky, Levi! Don’t you lecture me about taste, you want anything you don’t have!”



“They’re my sirens,” Asmodeus said, mildly, examining his claws. “Doesn’t that give me precedence?”



“As if!” Leviathan scoffed in tandem, and Mammon rolled his eyes.



“Ozzie, you can’t pay as well as I can, and you know it. Your little sirens know who pays the best here, and it ain’t you.”



“Oh, you take that back,” Leviathan growled, turning back to him. “I can pay twice as well as you, and with nicer things! What are you even giving them?”



“Cold hard cash, sweetheart!” Mammon cackled. “I bet you’re just giving them the stuff you don’t want any more from your grubby little hoard!”



Lucifer smiled with smug satisfaction as the squabbling grew, Leviathan’s faces both flushing in shades of indigo and teal while mandibles sprang forth from Mammon’s mouth and Asmodeus’ soft lights grew to a harsh neon that hurt the eyes. Belphegor raised an eyebrow at Lucifer reproachfully, while Beelzebub gave an undignified squawk of laughter.



Enough! Draw lots or something, I don’t care!” Satan brought his fist down on the solid arm of his chair. “You’ve got a month to decide between yourselves, and if you can’t give me a unanimous answer at the end of it, I’ll be adding another month. If I catch a single siren topside, or hear even a rumour of such a thing, I’ll triple it, so no bribes, threats, or sweet talk, do you hear me?”



With some grumbling, the three sins settled down, and Satan cast an angry eye up at Lucifer that told him he knew exactly what game he’d just been playing. But hey, these meetings could be so boring! What was he supposed to do?



Well, no matter. He tuned Satan’s gravelly voice out as he began imagining what he could make to give to his new friend. He was a big believer in handmade gifts, and he could make some pretty good stuff, though being happy with the finished product always eluded him somehow. There was always something that needed fixing, and if it was a gift for a brand new friend, it really needed the wow factor. Maybe a music box or something, or something to make his boat go faster. He’d seen things like that, and they were pretty fascinating, but it needed to be perfect.



“...Lucifer?” Belphegor called, gently.



“Hm?”



“We’re wrapping up.” She smiled. “Did you doze off again?”



Oops. Yes, he’d been doing exactly that. He did that pretty often, but his mind tended to get so tangled in what he was interested in, and these meetings were basically Satan telling them off or outlining who’d be doing what, and Lucifer…



Well, with the amount that people blamed him for perfectly ordinary things, he didn’t actually have to do too much to act as though he was performing his duties. Sometimes, he’d send phantom flames to wrap around a mast, or save the merfolk under their rule from the dreaded hunters, destroying their nets and sending their ships to the bottom of the ocean, or turn the sails into a flood of crabs. Just little things when he felt like it or when one of his people was in danger, but he didn’t do nearly as much as Satan or humanity thought he did. People cursed his name plenty without him lifting a finger, and they certainly didn’t recognise him when he did show up in person. He’d seen the paintings of a large, hulking creature who towered over the other Sins, impressive, powerful, and...well, incredibly far off base. Humanity had their own idea of Lucifer, and sure, that did sting a little, knowing they’d be disappointed if they knew the truth, but it did afford him a certain level of anonymity and freedom.



(Besides, not even Satan had that level of muscles. But hey, no kink shaming here.)



He swam down to join the others as Beelzebub began preparing a feast and Belphegor began summoning large, comfortable shells for them all to lounge in. Mammon and Leviathan began to bicker again, Satan chatting quietly to the little creature to his right, and Asmodeus began writing on a scroll with magic swirling around one claw, his face taking on a soft pink glow and a fond expression. Probably to that cute little clownfish mer-guy that he was living with, if Lucifer was any judge. With a fond smile of his own, Lucifer looked around his family, before sitting next to Belphegor, mind turning back to the gift he wanted to make the human, letting the hubbub of his siblings surround him as he drifted off into his mind.





Yes, it had to be just perfect.