Luuka/AN: AU using navy uniforms. You're tossed into it, kinda.

This fic is rated T but will go up to M from chapter 4. Warnings apply to the entire fiction, when they're updated I'll tell you at the top of a chapter. Genres are: Adventure, Fantasy, Hurt/Comfort, Mystery.

Warnings: mild gore, violence, death

The ocean was only as eerie and dissonant as it was believed to be. Sousuke breathed in the sea air, his teal eyes scanning the visible perimeter. Evening mist hung thick over the waves, impairing his ability to see more than several feet ahead... hearing a burst of commotion from his crew members, he stepped down from the bridge of the boat.

'What is it?' he asked sharply, 'did you find something?'

'No, Captain. Well, yes- a mermaid.'

'Woah, a live one?' A red head- Momotarou- pushed closer. 'She's not hurt, is she?'

Several seconds passed, before Rin spoke:

'H-hey... let her go, already...'

The mermaid stared- delicately blinking her eyelashes - before she was dropped back into the sea.

'Should have kept her...' Momotarou muttered. 'Could've caught Rin a girlfriend.'

Rin growled, close to biting off the hand which Momotarou offered to pass him a net. The net had been placed around the boat to dredge any corpses which had begun drifting atop the waves, but Sousuke hadn't expected it to entangle in anything living.

Hours ago, the Naval base at Iwatobi had received a request to dispatch on patrol and recover a mermaid carcass which had been spotted by a group of children, whom had clambered across several rocks and discovered it in a cave. Most mermaids made their homes underwater- preferring deep dwelts over shores- so it was unusual that their net had caught one swimming close to the surface.

Despite the fact that mermaids were commonly acknowledged to reside in Iwatobi's water, a sighting of one was uncommon... the dead body which the search expedition aimed to recover was no less strange.

'We're nearing the cave,' Sousuke intoned, as fragments of rock begun to poke through the mist. 'Once inside, pull up.'

'Yes, Sir,' the helmsman nodded. 'Pulling in now, Sir.'

A flock of two hundred seagulls screamed and flapped out of the way when the hull of the boat glided into the wide, yawning mouth of the cave. Stalagmites glittered. When Sousuke climbed onto foot with a team, his torch immediately found what they'd been searching for.

The mermaid didn't look as though it had washed up dead- it appeared to have been carried alive onto the rocks, where it couldn't swim away. There, it had turned it's back to it's attacker, which was when they'd chosen to stab it- the faint, ruby streaks beneath it's fingertips indicated that it had tried to drag itself away before the weapon had gone right through it's back then emerged from the other side.

Whatever it had been stabbed with was gone, but the amount of blood dried into the rocks around it hinted at multiple wounds that had long-since stopped oozing; the mermaid's fins were furled at the edges, it's fingers resembling the legs of a dead crab. Despite having known what to expect, seeing it made Sousuke feel... despondent.

'We'll bring it back for autopsy,' he reminded himself steely that it was an it- not a her. 'Make as little noise as possible. If there are any other mermaids in this area, we don't need to disturb them.'

'Captain!' A crew member insisted. 'I'll carry the body to the boat!'

'Wait.'

Before the corpse could be scooped up, Sousuke removed his uniform shirt and wrapped it around the deceased mermaid's shoulders to cover it's bare chest- nodding at the male who'd offered to retrieve it.

The next afternoon, Sousuke found Rin in the cafeteria of Iwatobi's naval base. He was surprised to see Rin: since his mother lived in the coastal town, Rin usually resided at home during his shore duty. Occasionally, he relapsed for training.

'Dedicated, Rin?'

'Hardly... Mikoshiba convinced me to do voluntary work- I have to give a sermon this afternoon. Sousuke. Do you have any advice for grade-schoolers about coastal safety?'

'Donno. Don't drown?'

'You are no help at all...' Rin looked incredibly disparaged. 'What are you up to, anyway?'

Since Sousuke wasn't in uniform, Rin wasn't required to address him as: 'Captain-' regardless, there was a degree of respect between them, which had roots ingrained in their childhood.

Sousuke had attended the same elementary school as Rin, and ultimately, Rin was one of the reasons why Sousuke had accepted the position leading the mermaid investigation at Iwatobi. Rin had recently returned from deployment, and it would be any number of months before he was stationed abroad; offering services here allowed the two of them to share a moment of nostalgia, before the world pulled them apart, once more.

'Not sure,' Sousuke admitted. 'I was thinking about checking on the mermaid we recovered.'

'You'd be wasting your time...'

'You saw it?'

'No way... I could barely look at that thing...' Rin's expression caught, between sympathy and disgust. 'I asked about how the autopsy was getting on. The staff in the morgue need to do some preservation work before they can take a closer look, but... they confirmed: there were at least five different stab wounds. On one of them... the weapon came out through the other side of her chest- it impaled her. I don't get it. Sousuke, if someone wanted to kill a mermaid, why didn't they just cut her throat, or... I don't know...' Rin shrugged. 'They didn't have to go that far.'

Rin picked sullenly at his meal, put off by his memory of the gnarled corpse. Sousuke's training had conditioned him for worse, yet he understood Rin's discomfort.

'At the very least, it takes a lot of manoeuvring to get a mermaid into that cave,' Sousuke changed the subject. 'Since it looks like that's where the stabbing occurred...'

'You think whoever did this has a bunch of resources?'

'There's a good chance of it.'

'Yeah? Maybe we're making progress, after all. So... got any ideas?'

'Nope.'

None whatsoever...

If Rin was correct- and the mermaid had been pierced through its middle- then when the autopsy lab finished with the body, they should be able to provide Sousuke with weapon dimensions: knowing what had stabbed the mermaid would be enlightening.

Furthermore- since he was committed to his role- it wouldn't hurt to learn why Iwatobi's police force had passed a case involving mermaids over to the navy, instead of the Marine Research centre. Was there more to this death than Sousuke thought?

Sousuke pushed it temporarily from his mind; Rin hadn't ambushed him for this dark discussion. He knew what Rin was going to say, though Sousuke wasn't going to be the one to bring it up-

'Hey... Haru's coming here, today, isn't he?'

Well... now, he didn't need to.

'Yeah?'

'Yeah... you know, I hate it when you pretend to have no idea what I'm talking about. You're supposed to introduce Haru to this place. Today- I'm reminding you, so you won't forget!'

'You're more familiar with him than I am,' pointed out Sousuke, his tone clipped. 'Rin. You'd do better to handle the introduction-'

'Your memory is awful... weren't you listening? I'm due for voluntary duty today. And you're the Captain of this investigation, aren't you? What, is that title for show?'

Sousuke's food was tasteless, and it's appeal wasn't increasing. After assigning himself to investigate the mermaid's death, Sousuke had written to the Marine Research Centre, and requested that they send a specialist to aid his team. They'd offered him a recently graduated intern: one he did not look forward to seeing again.

'It's rude to invite someone here then forget about them,' Rin announced. 'Don't unload Haru onto anyone else!'

'Right.'

Sousuke smiled. When Rin was gone, his expression rearranged into a frown.

Four years into his diving internship, and Haru's studies were finally over. He wasn't certain that deep sea diving was the best career for him- not entirely- but it felt right. High school hadn't provided any other opportunities, and studying had created too many unpaid bills for him to take up a new his superiors at the Marine Centre assigned him to a military investigation, Haru obeyed their orders and found his way to the Naval base.

Upon entering the facility, discord pervaded Haru: the person who'd arrived to greet him was familiar. They'd met on several interspersed occasions- whilst swimming in tournaments as children- but Haru remembered the details. The darkness which had permeated the water... the brooding sense of danger which had emanated from the opposite lane...

They weren't the sort of feelings Haru could forget, after swimming alongside someone like that. After a decade, it was disorienting to see Sousuke again.

'Nanase,' he begun- bypassing introductions. 'Come with me.'

He had almost a head on Haru in height: taller, broader and heavier with a dominating presence... imposing, unreadable. Haru recognised the 'Captain' insignia on his shoulderboards of his uniform.

'Do you know why you're here?' Sousuke asked.

'There's an investigation...'

'Several mermaid bodies have been discovered on the cliffs beneath us,' Sousuke revealed. 'The details are confidential, so don't expect them to be released unless they're required. The team I've assembled to get to the bottom of it have all received military-based training. That's why I wrote to your Research Centre... we need someone who understands the mermaid species.'

He faced Haru:

'I did some research on you.' The disapproval in Sousuke's voice was evident. 'Your internship was supposed to last for three years. Why did you take four to finish?'

'They extended it,' Haru explained. 'I failed an exam.'

'Surely you have to finish it to fail?'

His response was quiet.

'Shut up.'

'You don't talk to a uniformed officer that way,' Sousuke's tone deepened by several octaves. 'Learn that. If you expect to stay here.'

Irritation built inside of Haru- he turned away. During his first, theoretical exam, Haru had stopped midway through: this failure to complete a compulsory test had resulted in his studies being extended by one year. Yet, that was behind Haru: he'd completed his course. Still...

Why ask if you knew the answer? He thought, aggravated.

The remainder of his introduction was completed in silence- the end of the tour brought Haru to a corridor, where Sousuke slotted a card through a reader. The door slid upwards in response, revealing the outside.

The night was blue.

Iwatobi's cliffs looked disjointed, here- all unforgiving lines and broken edges... it seemed to Haru as if parts had simply fallen away. Waves thrashed against the stone, below tribes of stars.

'There's a separate building for sleeping quarters,' Sousuke informed Haru. 'Whether you stay here for the course of the investigation is your decision. For professional reasons, whilst working with us, you're required to wear a blank naval uniform. Any questions?'

'No.'

'As I've said, I researched you,' Sousuke folded his arms, before dipping his head and closing his eyes. 'You should know from the beginning that I don't tolerate a lack of interest. This investigation has the potential to span for months: I'm not going to waste time with someone who isn't committed. Do you understand?'

'Yes...'

'Make sure that you do. If you're serious, show up tomorrow. It's down to you.'