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Ok, Taesan knew a little bit about mermaids.
He, like any other kid born in the early 2000s, had grown up watching that weird Australian TV show H2O: Just Add Water on cable.
So when he said, “I think my new roommate is a mermaid,” he meant that. Literally. Not metaphorically. Not in the “he’s graceful and mysterious” way. No, Taesan genuinely thought the man living with him might, under the right circumstances, sprout a tail.
And honestly, it wasn’t even the weirdest conclusion he could’ve come to.
Leehan was odd.
When he moved in, he brought a big fish tank with him and a whole load of fun facts about “Corydoras” (a type of fish, by the way, Taesan had to google that). When asked where he was from, he said:
— I'm from the coast
To which Taesan responded with:
— Like… You’re from Busan?
— Yeah, you can say that
Odd answer, red flag number 1
Red flag number two came one day when Taesan got home and found Leehan watching the fish tank like it was a television, and that lasted for a while before he decided to say something
Only to have Leehan answer with:
— Fish get lonely if nobody pays attention to them.
Right, of course! Totally normal
When Taesan heard Leehan sing for the first time, it also rang a few bells. The younger boy showed a habit of singing in the shower, which was normal. Taesan just didn't expect for his voice to be so angelic, even if it was on the deeper side
It wasn’t just good. It was unreal.
His voice was low but resonant, smooth like running water over stone. It filled the room in a way that made everything else feel far away: his phone, his thoughts, even the faint hum of the air conditioner. For a moment, all Taesan could do was sit there, completely still, heart thudding like he’d forgotten how to breathe.
And when the song ended, there was this quiet stretch of air that felt charged, heavy, almost… sacred.
Leehan got out of their shared bathroom and looked up, embarrassed.
— Was that too loud?
Taesan blinked. — No. Just… you sound very good.
Leehan smiled, but it didn’t quite reach his eyes.
Taesan nodded slowly, but his brain was already connecting the dots. The fish tanks. The angelic voice. The vague mention of the coast.
So when he said, “I think my new roommate is a mermaid,” he wasn’t joking.
Not even a little.
Even if his friends disagree
— This again? — Riwoo asked
— I am not kidding.
— Ok, you’ve officially gone insane, sorry — Jaehyun said, sipping his soda
— Either that or you’ve been doing drugs — Woonhak completed — Which I don't judge you for, but maybe lower the dosage
He rolled his eyes
— I'm not crazy, I've been documenting it: he never touches water when I'm around, never talks about his past, he stares at technology like he doesn't understand it, and I'm talking about basic things like the microwave! Not to mention the talking with the fish and the singing.
— He studies marine biology, that explains the fish. Maybe he’s shy which explains him not spending time with you, and maybe his family was like anti-tech, and he’s getting used to it now — Riwoo suggested, all very plausible explanations.
— That explains everything except the singing! I swear guys it's creepy when you hear it.
Woonhak leaned forward, grinning.
— So, what, he’s gonna hypnotize you into walking into the ocean or something?
— Exactly! — Taesan said, smacking the table for emphasis. — That’s what I’m saying! It’s siren behavior!
Jaehyun snorted so hard he nearly spilled his drink. — Bro, please. You’ve been watching too much late-night Discovery Channel.
Taesan glared at him but didn’t answer. Because fine, perhaps it did sound insane out loud. But it didn’t feel insane.
Not when every time Leehan sang, the world went still.
Not when the guy would flinch if Taesan accidentally splashed water near him.
And definitely not when he’d caught Leehan once, late at night, humming to the fish — and the fish actually swam closer, like they understood him.
That wasn’t normal.
The days passed, but the strangeness did not.
Leehan kept being his weird self, talking to fish and singing melodies Taesan couldn't tune out as much as he tried
And yes, maybe it was the stress of exam week, or maybe it was the fact that he couldn't just leave well enough alone. He needed to know
He became even more observant, borderline stalking. Making little mental notes of his roommates actions
Little things, that added up into a bigger picture he was painting
He googled Leehan and found nothing, not even a cringe Instagram post. He asked for his file at the office and discovered he didn't have an address in Busan put in. Not only that, but he tried asking about his family casually and was met with silence
So instead of searching for Leehan he searched for mermaids and their lore, something had to prove it
He found articles about sirens luring sailors, about merfolk hiding among humans, about water being both their source of power and their weakness. He read about how they supposedly couldn't maintain their human form if they came in contact with salt water, how they were drawn to the ocean like moths to flame, how their voices could enchant anyone who listened too closely.
The more he read, the more everything clicked into place.
And the more terrified he became that he might actually be right.
So screw it, he had to test it.
He skipped class, took a two-hour train to Incheon, and filled a plastic bottle with real seawater. He told himself it was ridiculous — insane, even — but his hands still trembled as he sealed the cap.
Because deep down, some part of him believed it.
When he came back to the dorm that night, the lights were dim. Leehan sat by the fish tank again, head tilted toward the glass, lips moving silently, he was maybe talking to the fish, maybe humming.
Taesan’s heart hammered.
He held the bottle behind his back.
— Hey, Leehan?
The other boy turned, his usual soft smile in place.
— You’re home early.
— Yeah — Taesan said, trying to sound casual.
He uncapped the bottle and, as soon as Leehan turned around, he poured it over his head in one single motion.
The seawater splashed across Leehan’s hair and shoulders, dripping down his neck, soaking into his shirt.
For half a second, nothing happened.
Then everything did.
Leehan gasped and stumbled backward, hands flying to his head.
The bottle slipped from Taesan’s hand and clattered to the floor, rolling under the desk.
— What… — he started, but the word caught in his throat.
Because Leehan was glowing.
Not brightly, just a faint shimmer that outlined him in blue-white light. His soaked shirt clung to his skin, and for a moment it looked like his veins were glowing faintly under the surface, liquid silver running through them.
Then his legs gave out.
Leehan dropped to the floor with a choked sound, clutching at his thighs as if in pain. His jeans darkened, shimmered, shifted. The fabric dissolved into light, then into something else entirely — something alive. Scales unfurled across his skin like petals opening underwater, glinting silver and deep turquoise. His knees fused together in a single, fluid motion, and before Taesan’s brain could even begin to comprehend what he was seeing, there were no legs anymore.
There was a tail.
An honest-to-god, gleaming, beautiful tail.
Taesan stumbled back, eyes wide, heart thundering.
— Holy shit.
Leehan blinked slowly, then raised his head. His voice, when he spoke, wasn’t angry. Just tired. And maybe a little curious.
— How did you figure it out?
— I didn’t! — Taesan stammered. — Well, I mean I did, but I didn't— I wasn’t sure!
Leehan tilted his head, water dripping from his hair and down his cheek. His expression was unreadable, eyes darker than Taesan had ever seen.
— There are no beaches in Seoul.
— Yeah. — Taesan swallowed, his throat dry. — I took a train. To Incheon.
Leehan stared at him for a moment, like he couldn’t decide whether to laugh or be horrified.
— You went to Incheon. For this?
Taesan nodded weakly. — Yeah.
A long silence passed. The hum of the aquarium filled it, calm and steady, like background music to something unreal.
Finally, Leehan sighed, not angry, — You really are something else.
Taesan crouched a little, careful not to get closer than necessary. His eyes couldn’t seem to look away from the tail, from the way the scales shifted like light through water.
— It’s real — he murmured, almost to himself. — You’re real.
Leehan gave a small, humorless smile.
— Unfortunately.
Taesan crouched to the floor, sitting beside him
— Can I… touch you?
Leehan nodded, taking his hand and guiding it to the cold scales, His hand lingered over his for a moment, guiding, then retreating.
— It’s cold, right? — he said softly.
Taesan nodded mutely. He couldn’t think of anything to say. His mind was still trying to reconcile the image before him.
— Does it hurt? — He asked, after a pause.
Leehan tilted his head. — Changing? Not really. Just… draining. It’s like holding your breath too long.
He looked at the empty bottle that was forgotten on the floor. — You really took a train just to do that? You didnt have to.
— Yeah — Taesan said, suddenly sheepish. — I thought I was going crazy. I had to know.
Leehan’s expression softened in a way Taesan hadn’t seen before, something almost tender.
— You could’ve just asked.
— Would you have told me the truth?
Leehan hesitated, eyes lowering. The answer was clear before he even said it.
— No.
Silence again, but it wasn’t heavy this time. Just full of everything Taesan didn’t know how to say, and everything Leehan couldn’t.
The hum of the aquarium filled the space between them. Taesan could see the fish darting near the glass, restless, like they sensed something.
Then Leehan sighed and looked toward the window.
— Can you get me a towel so we can speed this up? I dont wanna be on the floor all night
— Oh. Right.
Without thinking, Taesan got up and grabbed a towel from the bathroom and handed it to Leehan
— Thanks, — he murmured.
Taesan hesitated. — What do we do now?
Leehan gave a faint, wry smile.
— Now? You forget this happened.
— Yeah, uh… that’s gonna be kind of hard.
— Try anyway.
Taesan exhaled slowly, still recovering from the shock
— So… mermaids are real.
— Sirens, technically, — Leehan said, rubbing his face with the towel.
— Right. Sorry.
Leehan glanced up at him, eyes glinting faintly with something unreadable.
— You’re not going to tell anyone, are you?
Taesan’s chest tightened at the quiet seriousness in his tone. Because he planned on telling his friends, just to prove he was not crazy
— No. Of course not. I’m not that stupid.
Leehan smiled faintly.
— Good. Because if you did… I’d have to move again. And I kind of like it here.
Taesan smiled back, awkwardly but genuine.
— Then I guess I’ll keep your secret.
Leehan’s gaze softened again, something almost like gratitude flickering there.
— Thanks, Taesan.
For a long moment, they just sat there, but then Taesan, half-laughing and still breathless, said,
— So… do you eat sushi or is that, like, cannibalism?
Leehan groaned and threw the towel at his face.
By morning, Taesan had convinced himself that the entire thing had been a fever dream.
There was no way he had actually poured seawater on his roommate and watched him sprout a tail like some K-drama plot twist sponsored by Discovery Channel. He’d clearly been sleep-deprived, over-caffeinated, and one delusion away from becoming a full-time conspiracy YouTuber.
Except, he did. And now he’s eating breakfast with said mermaid
— I have questions — He announced, drawing Leehan´s attention
— You already saw the tail, isn’t that enough? — Leehan said flatly, shoving a spoonful of cereal into his mouth.
— No, it’s not enough! — Taesan insisted, sitting cross-legged across from him at their tiny dorm table. — You can’t just turn into a mythical sea creature in front of me and then go back to eating Froot Loops. That’s not how life works, dude.
Leehan gave him a deadpan look. — I still need breakfast whether I have legs or a tail.
— Oh, sure, right, mermaids need their balanced diet.What do you even eat underwater? Seaweed? Clams? Other mermaids?
— Humans, that's why we sink ships — Leehan said without even looking up
Taesan choked on his orange juice
— I'm joking! We eat fish. Just like sharks — Leehan clarified, trying not to laugh at his roommates reactions
Taesan groaned. — You’re doing this on purpose.
— Maybe, — Leehan said, with the faintest twitch of a smile.
But Taesan didn't stop there
— Were you born a mermaid? Or were you like cursed?
Leehan blinked.
— Cursed?
— When I was researching mermaids…
— You were researching?
— Yes. — He admitted, a bit embarrassed — I wanted to understand what I was dealing with. Anyway, I came across this book that said mermaids were immortal girls cursed by the ocean and forced to lure sailors for a hundred years.
Leehan coughed
— You read “The Siren”? That book sucks — He sighed, as if he was personally offended — Yes, I was born a mermaid, but no, I'm not immortal. I mean I don't age like humans do, but I can get hurt, sick and die, naturally
Taesan nodded slowly, processing that. — So, like… extended warranty on life, but no immortality.
Leehan sighed yet again. — Something like that.
Taesan leaned back, studying him.
— You know, for a mythical creature, you’re surprisingly normal.
Leehan’s lips curved into the faintest smirk
— Thank you? — He said more as a suggestion
The days passed, but Taesan’s curiosity didn’t.
His questions ranged from “Can you actually hypnotize someone with your voice?” (Answer: yes, under very specific circumstances) to “How fast can you swim?” (Answer: “Speed and time are human concepts, so… I’m not sure.”).
Until one morning, while Leehan was elbow-deep in cleaning his aquarium, (Wearing his usual rubber gloves) Taesan hit him with:
— Wait, how can you stay on land without, like, drying out?
Leehan didn’t even glance up.
— Bathtub.
Taesan blinked. — Bathtub? Like the one in our bathroom?
— Yeah, — Leehan said casually, adjusting the rubber gloves he was wearing. — I just fill it and stay submerged for a bit. Keeps me hydrated.
Taesan stared at him, jaw slack. — You’re telling me… you’ve been turning back into a mermaid in our dorm bathtub?
Leehan shrugged. — Well, only when I need to. I can control it now.
— Wait—any water turns you into a mermaid? Like anyhting?
— Technically, yes. Any natural water source. Even tap water works.
Taesan froze. His brain short-circuited for a full three seconds before the realization hit him like a bus.
— So I didn’t need to bring sea water all the way from Incheon?! — he demanded.
Leehan looked mildly amused, like he’d been waiting for this outburst.
— Apparently not. You should really check your sources next time,
Taesan threw his hands up. — You owe me nine thousand won.
Leehan just went back to scrubbing algae off the glass, utterly unbothered.
— For what it’s worth, I appreciate the effort.
— Oh, sure, — Taesan muttered.
Leehan smirked, still not looking up. — You’re welcome to join next time. If you really wanna see my tail again.
Taesan sputtered, nearly dropping his phone.
— Really?
By the time Taesan agreed to it, he wasn’t entirely sure how.
One minute, Leehan was teasing him about “wanting to see his tail again,” and the next, they were standing in the cramped dorm bathroom, steam curling lazily against the mirror.
The fluorescent light buzzed overhead, too bright for the hour. Taesan leaned against the sink, arms folded, his back turned to Leehan as the other waited for the tub to fill up
Cause seeing his tail was fine, but seeing him naked was too intimate
— You humans and your scandal with nudity — Leehan mocked
Taesan didn't indulge
— Just tell me when to turn around, and please don't try and drown me once I do
— Don't worry — Leehan said sweetly — There's barely room for that
A few minutes go by until he announces he’s ready
Taesan forgot to breathe for a moment.
Leehan rested an elbow on the edge of the tub, looking more at peace than Taesan had ever seen him. The scales along his tail glimmered like glass, in shades of green and blue.
— You always look so shocked, — he said softly.
— It’s not every day your roommate turns into something out of a dream, — Taesan replied, trying for a laugh. It came out quieter than he expected.
Leehan smiled faintly. — I’ll take that as a compliment.
Silence settled between them, warm and fragile. The only sound was the water’s gentle movement and the slow hum of the building pipes.
— You said you can go back anytime, right? — Taesan asked after a while.
Leehan’s smile didn’t fade, but his eyes dropped. — Yeah. Anytime.
— So… why don’t you?
There was a pause. Then, softly —
— Because every time I think about leaving, I realize I might miss something here.
Taesan’s chest tightened. He didn’t know what to say to that. He wanted to tell him to stay — that he should. But the words stuck in his throat.
Leehan flicked his tail lightly, breaking the quiet. — You’re staring again.
Taesan exhaled through his nose. — You always say that.
— Only when it’s true.
A small smile tugged at the corner of Taesan’s mouth. He looked down at the water, where light scattered in delicate fragments across Leehan’s tail.
He wondered if it would always look that beautiful or if someday, when Leehan was gone, he’d forget the exact shade of blue.
— You’ll have to go back eventually, won’t you? — he asked, barely above a whisper.
Leehan looked up then, meeting his gaze. His eyes were calm, ancient in a way Taesan couldn’t describe.
— Probably. — A pause. Then, more softly: — Just not tonight.
Taesan nodded, and that was enough.
The light flickered once. Outside, rain began to fall, faint and rhythmic, like the ocean calling from far away.
And in the tiny bathroom, surrounded by tile and steam, they stayed like that a little longer.
Neither of them spoke.
Because for now, not tonight was enough.