Actions

Work Header

Rating:
Archive Warning:
Category:
Fandom:
Relationships:
Characters:
Additional Tags:
Language:
English
Stats:
Published:
2025-05-03
Updated:
2025-08-07
Words:
30,434
Chapters:
7/?
Comments:
42
Kudos:
115
Bookmarks:
26
Hits:
1,798

Sunlit Waves and Lunar Tides

Summary:

Notes:

So this is loosely taking ideas from the books, but I never read the books so book names are either cameos, or I wanted to use a fnaf relevant character to fulfill a certain role without inventing a new one. All of these characters here have lived completely different, animatronic-free lives, lol. You can almost consider them completely different characters in some cases. That said, I hope you enjoy my Mer AU world that I've crafted :D

Chapter 1: Bubbles and Squeaks

Notes:

(See the end of the chapter for notes.)

Chapter Text

Sun exhaled through his nose, watching tiny pearls of air spew out. This was the worst. The worst part of The day. No sleep, no play. Just. Waiting. Letting out a frustrated whoop that reverberated through the water, Sun flicked his tail and propelled himself like a dart. Arching his body upward, he directed his momentum into a series of tight loops. Humans called this trick “donuts”. A human had let him sniff a donut once. Wouldn't let him eat it, though. They had then proceeded to eat it in front of him much to his great indignance. Why couldn't he eat it? The human had just laughed at Sun's offended squeals and chiding chirrups.

That had been his old trainer, “Henry”. Sun missed him.

Getting bored of donuts— the trick— he allowed his remaining momentum to carry him to the edge of his home, nose bumping against the glass. His “tank” was in the middle of the aquarium atrium, front and center. He stared intently at the doors, waiting for his new trainer, “Cassie” to walk in.

He would take the janitor at this point, and that guy barely ever glanced his way.

Sun sang out mournfully, hearing his voice bounce against the glass back at him. He allowed his body to sink, nose sliding down the glass with a squealing rubber noise to complete the dramatic display. He was bored.

And hungry.

The door creaked open. The janitor—? No, Cassie? It was Cassie!!

Sun squealed as loud as he could, flicking his tail and performing a rapid series of horizontal figure eights.

He heard her laugh echo to him. Through the glass, through the water, twisted and warped.

“I'll be right there, Sun, I just need to get changed, first!”

Sun trilled as loudly as he could so his affirmation could make it through the water, through the glass, to her ears.

It must have worked because she laughed again, waving before heading off in effortless quick strides.

Sun marveled, watching the legs chop back and forth, back and forth. He looked back at his one “leg”, spreading his tail fin. Was the fin a foot? Was the whole thing a leg or a tail?

Sun flopped his fin back down and turned back to the glass, trying to peer past his reflection to watch Cassie disappear through the “employees” only door.

Once he'd seen a guest try to sneak in. He'd wailed loudly and scratched the glass, pointing with his nose. When a curious guard went to investigate, he caught the human trying to steal an “employee ID” from the “locker room”.

Sun had gotten lots of headpats and extra treats that day. People had said he was “so smart” and lots more people than normal came to watch him do tricks for a few weeks after.

The creak of hinges and a bang interrupted his happy reminiscing. Sun turned his attention back to the main entrance. One of the doors had been shoved open too hard, resulting in the bang as it hit the wall. He heard some sharp noises that he recognized as bad words and wrinkled his nose distastefully. There were several employees and a few other humans shoving a large tank on a wheeled cart inside.

Sun perked up curiously. The tank was covered in a black tarp, but Sun recognized the rectangular size and shape of it. Not to mention as someone accidentally thunked it against the doorframe water sloshed out.

Fanning out the seven long fins around his head to capture all sound in that direction, Sun listened intently.

“... Careful ya idjat! This thing’s in bad shape!”

“Sorry, sir.”

“Whoa, whoa, what's going on here?” Another human was rushing from the employee door. Not Cassie. She was wearing a long white coat.

“We need to get this to the labs, quick!”

“Poor thing got too close to the surface. Its whole back has been razed by a speed boat blade.”

He heard a hiss of shock and sympathy from White Coat, “Follow me, we have a medical room open in B2.”

Safely through the front entrance, the humans maneuvered it after the employee, trying to rush without sloshing more water.

Sun released a low trill of sympathy, not too loud to hear. He didn't want to distract the humans in an emergency situation. Watching them carefully slide through the employee entrance, Sun wondered if it was another manatee.

A click vibrated to him from the open water above. Excitement ejecting him from his somber thoughts, Sun torpedoed up so fast he breached the water by nearly six feet (close to his record) letting out a loud squeal of joy. In the brief moment at the peak of his leap when his body hadn't got the memo to fall yet, Sun could see Cassie's beaming smile looking up at him.

Gravity insisted that air didn't work the same as water and dragged him back down. Sun stretched out his body stomach first so there was a satisfying whompf and a big splash on impact.

Cassie laughed again, not minding the soak in her waterwear, “Well, since I'm already wet I'm ready to go! Lemme just chuck this bucket of fish in first.”

Sun trilled with joy, tail walking backwards along the surface of the water ‘till he lost balance and flopped over. He wasn't as good at that trick as dolphins, but he'd learned it as a pup when he was in a smaller tank next to them.

The familiar splik splat splosh of his meal plunking into the water drove him back under the surface. He made a game of catching them all before they floated up again, feeling the slimy cool bodies slide satisfyingly down his throat. Delicious!

From under the surface, Sun could see the rippling silhouette of Cassie. Arms steepled above her head as she gracefully dove into the tank, bubbles swirled around her in a flurry as she cut downwards through the water. Sun darted toward her, angling his body so he was swimming in pace with her. Carving upwards through translucent aqua, she flipped her braids back as she breached the water. Sun tried to mimic the move, flipping the long fins that sprouted around his head like sun rays. One of them wapped him across the eyes, blinding him with a wet smack.

Sun shook his head to dislodge it as the echoes of Cassie's laugh bounced off the surface of the water.

He gave his best dark glare, but he couldn't keep it up in the light of her delighted smile.

“Alright Sunnyshine, how ‘bout we go over our routine to warm up?”

Sun gave squeals and clicks of confirmation, clapping his hands like he'd seen seals do.

They ran through all of Sun's known tricks. Back flips, leap-overs, donuts, figure eights, twirls, torpedo. Cassie watched Sun carefully as she gave each hand signal, making sure he hadn't developed any deviations. Sun gave a mental indignant sniff. He was always perfect!

After that was some synchronized swimming. Sun watched Cassie carefully to make sure she hadn't developed any deviations. Nope! Not this time!

All was in order for their performances for the day.

She hauled herself out of the water, sitting at the edge of Sun's “pool” while she wrung out her hair, “Lookin’ good, Sunny!” She grinned.

Sun stretched his cheeks wide, grinning back. She laughed, the noise bouncing off the water.

Standing up, she shook herself off and dripped over to a towel, “See ya Sunny! Gotta feed the other residents for the morning!”

Sun raised his tail fin, spreading it wide to wave goodbye. Waving back, she slipped through the door.

Sun sighed, letting himself sink below the water.

This part wasn't so bad. Now he at least had a full stomach and anticipation building up. With a flick of his tail, he slid through the water to the left of his tank. Through the glass, across the room, and against the wall was another larger tank, spanning that entire side. Sun could see the other Mers still working out wrinkles and rehearsing new tricks with their humans.

He recounted their names in his head. Freddy, Bonnie, Roxy…

Monty and Chica used to be there, too, but they got moved to their own tanks.

He still remembered the huge commotion. A crowd of employees were suddenly swarming his neighbors. One of the diving humans pointed an oddly shaped stick at Monty that made him sluggish.

Sun had seen tendrils of pinkish red drifting from Bonnie who was lying on the sand.

Bonnie was okay now, but for weeks he wouldn't leave one of the caves in their home. Freddy had brought him food and slowly coaxed him out in a display of empathy that had impressed the humans. They still talked about Freddy’s kindness on tours. He'd become the main draw of the aquarium, his face all over shirts and bags and other things humans would wear. They even changed the logo to his placid smiling face.

Sun wasn't jealous, even if his tricks were better than Freddy's standard routine.

Though, maybe that was because Freddy was older. The orange Mer had been here as long as he could remember. Sun was still just a juvenile, and the newest Mer attraction.

Even though he felt he was more popular right now, Freddy was a staple. He doubted they'd change the logo to his own sunny face.

And then there was Chica. One day Roxy got angry and started chasing her around as soon as feeding started. Chica was removed from the tank shortly after. He overheard that when the humans studied the “security feed” (whatever that was) she'd been consistently sneaking food from everyone else's meals on top of her own ‘till her roommates became underfed and she became overfed.

She'd been moved to her own tank where her diet could be regulated. Apparently she didn't have a stopper that told her when to stop being hungry, and was in danger of hurting herself if left to her own devices.

Performance rehearsals over, the excitement of activity ceased as the humans left. The bigger Mers drifted lazily. Except Roxy, who constantly swam laps around her tank. Sun curved his head over his shoulder and beyond, body following as he pushed through the water to the other side of his tank.

On the other side were the freshwater Mers. Unlike his fellow sea Mers who were all bright and colorful— oranges, blues, greens, and purples— river Mers all looked the same. Shades of boring gray with the only splash of color being orange circles on their cheeks. They also had white spots encompassing each empty black eye, giving the impression of blank wide-eyed staring. Several were staring at him right now.

He'd heard they weren't very smart, barely able to learn the most basic of tricks. Sun stuck out his tongue. They didn't so much as blink.

Wrinkling his nose, he swam back to monitor the entrance. Guests started coming in shortly after the employees did.

There! The first ones! Two adult humans with a little one between them. Sun let out a shrill squeal for attention and watched the little one's face light up as he swam around excitedly.

That is what Sun lived for.

~~~

The growing rumble of human feet vibrated through the water down to him. Sun was poised several feet below the surface, watching sparkles and beams of light dance and play above him.

Like all tanks on the entry floor, Sun's rose up past the ceiling and opened into the second floor where the shows were hosted.

His show was scheduled to start in ten minutes.

He could hear the rolling thunder of hundreds of feet crossing the floor above before scattering like droplets into the seating stands.

The final pitter-patters of stragglers came in and joined the waiting mass above.

Spotting the tip top of Cassie's head rippling at the edge of the shallow drop-off, he picked up the upbeat cadence of her “show voice” as she started the educational introduction about Mers. Her voice was distorted and muffled by the water.

“Hello, my name is Cassie, and I'll be your host for this show! I'm the trainer for the Mer who lives in this tank, Sun! I bet a lot of you saw him when you walked in! Mers are a very recent discovery in the animal kingdom! They are extremely intelligent and expressive creatures. Sun, why don't you come up and say hello?”

That was his cue.

Pushing up through the slight resistance, it broke apart into thin cool air. Sun released a shrill trill of happiness, the results of his surfacing raining down on him.

Sun scanned the crowd, taking in smiles and clapping hands.

Cassie laughed as the last of the droplets rained down, “This is Sun! Say hello, Sun!”

He raised his arms and tail fin, spreading them wide and trying to mimic the sound for “hello”. He'd long learned human noises didn't come out of his mouth right, an odd squeal and a few clicks being his best attempt.

Laughter and a few exclamations of delight from the audience.

Voice clear and loud now that Sun was above the water, Cassie continued, “Mers were almost named ‘mermaids’ because of how expressive they are and the amount of articulation in their webbed hands.” She turned to him, “Sun, can you give me your happy face?”

Making sure to keep his lips mostly hiding his sharp teeth, Sun stretched his cheeks and opened his mouth.

Noises of delight and waves from the audience.

“Now give me your grumpy face.”

Sun closed his mouth as small as he could and lowered his brows.

A chorus of “Aaaaaaw!”s and laughter.

“Now your surprised face!”

Sun widened his eyes, forming an O with his mouth and clapping his hands to the sides of his head.

More laughter and squeals of delight from children in the audience.

“As for their hands, Sunny, catch!”

Cassie lobbed a ball at him.

Sun kicked up out of the water with his tail to catch it, gripping the smooth rubbery surface carefully in his large webbed hand. Feeling it slip, he dug his claws into it lightly. Just enough to keep it steady without leaving obvious marks.

“Okay, Sun, now give it back!”

Sun looked between her and the ball like he was considering it, then pulled it to his chest and turned his head away with his nose in the air. He closed his eyes and made a petulant squeak for good measure.

Roars of unexpected delight through the audience.

“Pweaaase Sunny? Can I have the ball back?”

Sun turned back to see Cassie leaning toward him giving her best “please face”.

Tapping his chin with his other claw, Sun gave a relenting squeak and threw it back at her.

She caught it, laughing, “Alright, now for the main show to start.”

She raised her hand and did a spin motion. Sun leaped up, arcing his body in a perfect ring as he did a backflip. She tossed him a treat and he caught it mid-air in his mouth.

Following her hand motions he did front flips, leapt side to side, figure eights. Then Cassie dove in and they did their dance routine.

Cassie climbed out of the water and into thundering applause. When the sound died down, she continued her rehearsed bit.

“The Educational Marine Institute for Learning Youth, or E.M.I.L.Y. Aquarium, focuses on rescuing aquatic animals and supporting other organizations focused on reducing waste and conserving wildlife in the ocean. I ask that you please donate to support our research and medical branches to help us help creatures like Sun.”

Sun trilled and waved like he was supposed to, but people were already getting out of the stands and migrating towards the exit.

Cassie crouched down, offering another treat. Sun swam over, sliding onto the shallow “cliff” just under the surface of the water. Planting the palms of his hands and dragging himself forward, Sun stretched out his neck to pluck the treat from her hand. Cassie rubbed the top of his head, and Sun squinched his eyes closed in bliss.

He had one more show later in the day. For now he could rest.

And be bored.

As the last of the people left, Cassie gave him a final pat before standing up. Sun let out a mournful whistle as she locked the gate of the plexiglass barrier that kept him from the ground above the water and the surrounding stands.

The final door beyond thunked shut, followed by a click as Cassie locked it behind her.

Left alone in his empty pool, Sun took a gulp of the thin moist air around him to let out a dramatic sigh. As always, it felt like he wasn't getting quite enough air with each breath above water. It was tolerable for a time, but got gradually harder ‘till he felt like he was suffocating no matter how deep he breathed.

He'd heard a “fun Mer fact” that a fully grown Mer could last 2 hours out of water before it became dangerous (longer if the surrounding air was moist enough). Out of curiosity Sun had lasted half an hour before feeling too uncomfortable to want to push it further.

Turning his head around, his flexible body folded almost double as he pushed himself back toward the edge of the “cliff”. He dipped his head, splashing a few times in the shallows to soak his gills.

Sun slid nose first off the edge seamlessly into the water with barely a bloop. He spread himself out, slowing his dive into an aimless float.

It was hard to adjust from excitement, noise, and people to empty silence.

He trilled and watched bubbles exit his mouth in a thin stream, curving upwards and scattering at the end.

He twisted to face the twinkling surface, opening his mouth wide and whoofing out bubble rings— a trick Cassie had taught him. Once she made a bubble ring big enough for him to swim through. She'd lamented that she hadn't figured out how to do that again.

The first two rings fizzled out, barely formed. The third one held steady but stayed rather small before it disintegrated.

Sun flipped back around and looked down at the sand and rocky structures below him. Real and fake seaweed drifted in the currents caused by the water filter, a low constant hum in the background. He swam down to study the real and fake coral and the real and fake rocks. He could tell them apart by smell, earthy sandy green contrasting with flat pungent tanginess. It was only noticeable up close, all other scents drowned out by salt and fish.

The mouth of a cave structure yawned in the corner as always— meant to give him privacy, but Sun rarely used it. Too dark. And people were the highlight of his life! Why wouldn't he want to be seen?

Speaking of which, several people were milling about the general aquarium. Sun whistled and swam back and forth in excited wave motions for attention. It didn't take much effort to draw a small crowd and start performing tricks on his own.

~~~

Echoing clicks as lights shut off marked the official end of the day. The aquarium was never truly dark. The upper floor show area had a large glass dome in the ceiling, filtering moonlight into the water. Everything hushed and tinted a cool blue. Low light ripples reflected from the water played on the tile floor outside the glass.

Sun swam upward, seeking the sky. Warm water gave way to cooling air, silver droplets scattering up and away.

The deep blue abyss of the endless Sky Ocean where birds swam stretched above him. Searching the murky heights, Sun spotted the Moon— a fading crescent floating just at the edge of the domed window. Counting the stars he could see three… four… six. For a dizzying moment the memory of seeing hundreds of tiny sparkles shimmering in the dark washed over him. Sun blinked, the ghost of the memory already fading.

Maybe stars burnt out like the lightbulbs of the aquarium occasionally did, but the sky was too high to change them.

The ripples of a sound from below tickled his fins, something loud enough to travel all the way through the water to here. He didn't hear it as much as felt it— the vibration of noise.

Diving back down, Sun nosed through the water, spreading his fins and catching movement by the employee’s only door.

It wasn't odd for humans to still be here at this hour. Sun was certain some humans even slept here— in the lower levels. The “secret labs”.

He perked up when he saw Charlotte heading the group, tall and willowy with straight black hair and ivory skin. She seemed to be in charge now, crisp and intense with her speech and attitude. It still felt jarring. Sun remembered the shy girl who stared at him in wonder when Henry introduced them.

The strange female human came with Henry, guarded wonder and a glint of something else in her eyes.

“Charlie, this is Sun, Sun, this is my daughter Charlotte. It’s okay, you can pet him, he won't bite”

She reached out hesitantly, slowly opening the palm of her hand. With an excited trill Sun shoved his head into her palm, always eager for pets.

Jolting with surprise at first, she relaxed and began rubbing back and forth. Sun caught a little smile through the fingers on his face, a small hint of the unguarded person within.

The Charlie of now didn't look at him with the same wonder she had when she'd gently rubbed his head.

Something had changed after Henry “retired”, whatever that meant.

He remembered that, too.

Sitting at the edge of the water, staring at nothing, Henry let out a heavy sigh.

“Sunny, I'm retiring soon.”

Sun gave a little chirrup in response.

“That means you probably won't see me again.”

Immediately Sun gave a series of indignant squawking, slapping the water angrily with his tail.

Instead of laughing like he normally did at Sun's tantrums, he just smiled sadly.

Sun went quiet, letting out one last whimper.

Lifting a hand, he rubbed Sun's head, “I'm sorry, Sunny, but there's some things I have to do. Some things to look into. And I need the time to do them. This place, all of you, will be in Charlie’s hands. She will protect you.”

Sun lay his head on Henry's knee, releasing a mournful whistle.

Henry stayed ‘till the lights went out and the moon rose high and Sun couldn't keep his eyes open any longer. When he woke up, he was in the water, and Henry was gone.

Sun blinked out of the memory as Charlie walked right up to the glass.

Her calculating gaze roamed over him.

People staring at him never made him feel self-conscious, but Charlie managed it.

Her voice muffled through the glass, “You're sure? They look nothing alike.”

The frazzled white lab coat behind her spoke up, “Yes! We thought so, too. We checked twice, but the DNA sample’s a match with Sun. Both 50% tropical and 50% deepsea and sharing 50% of their overall DNA.”

What?

Charlie spun to face him, short black dress twirling slightly, “And he'll live?”

White coat straightened up and gave a solemn nod, “We'll give everything we have to make sure he does, but he's a fighter. I haven't seen spirit like this since Roxy. Nearly took one of our doctor's hands off even in that state.

“I presume the doctor is well and has been fully compensated?” She whisked her jet black hair over her shoulder back into its straight-cut position.

“Yes, yes, it's all been taken care of, he won't have any permanent injuries.” White coat's voice dropped to a mumble, “He might have scars for life, though.”

“All within the contract. There's no grounds for a lawsuit, then.” She turned her green eyes back to Sun, “As for this one, he's had zero social contact with other Mers. If we plan on introducing them both, that has to change.”

White coat scratched his head, “Well, we could put him in the tank with Freddy and the gang.”

Her green eyes searched Sun's face, considering, “No. Three adult Mers might be overwhelming. He can share Chica's tank for a while. Aside from working something out for feeding time, she's friendly and social enough.”

“Uh, alright. I'll start the preparations to move tanks. We’ll probably be ready tomorrow after the aquarium's closed.”

“Good.” Pivoting toward the door, Charlie crisply clicked in her high heels to the exit. Sun watched her go, the black and white bands of her stockings and sleeves flashing eye-catchingly in the dark.

When the exit door closed with a resounding thud of finality, Sun looked back to find the white coat staring at him.

Sun stared back. “DNA? Percent? A match? Is all that meaning what I think it means?” he asked before he could even think.

Despite his best attempt to mimic human language, he could tell from the odd clicks and squeals that none of it came out right. Something in his throat, tongue, or vocal cords were wrong.

The white coat smiled, giving a little chuckle at the display, “If only you could understand us, little Sunny. I can imagine how excited you'd be if you knew you had a brother.” Adjusting his glasses and pulling his phone out, he walked away tapping at the screen.

What?!

Sun had never been in shock before.

Maybe this was what it felt like.

The world seemed to blur and ripple as his head echoed with that last word.

Brother brother brother.

Sun blinked, feeling gritty sand rubbing against his back. He pushed up from the ground, flipping over. Had he fainted?

He gripped his still slightly dizzy head, thoughts reeling. He had a BROTHER!

Notes:

Here's a link to the summary image on my tumblr.