Haikyuu Oneshots

Oihina Mermaid AU

Another Oihina fanfic because I'm obsessed. In this fanfic, Hinata is a half-mermaid half-siren, while Iwaizumi is his main caretaker. Oikawa, being an asshole, begs to meet the siren.

Oikawa watched the small boy swimming around restlessly.

"Half siren half merman, huh?" he asked, tapping the glass to get his attention. The boy whipped his head around, cautiously swimming over to him.

"What's his name?" Oikawa asked. He smiled at the boy, who pressed his hands against the glass, as if trying to get a better look at him.

"Shoyo." Iwaizumi replied, heading over next to him. "Don't get so friendly with him. He could kill you."

"Aw, he's such a small kid. What harm could he do?" Oikawa protested, waving at Shoyo. The boy gave him a look of confusion, unsure what that hand signal was supposed to mean. Oikawa blinked as he opened his mouth, seeming to be yelling at him or something.

"Is he trying to kill me?" he asked, turning to Iwaizumi.

"Probably." Iwaizumi said, shrugging. They'd soundproofed the tank to make sure none of the researchers would be hurt, but if he were to be honest, he wanted to hear what kind of sound the boy was making.

Oikawa pouted, plopping down on the floor. Shoyo followed him, diving deeper to the bottom of the tank to meet his eyes.

And he could see the murderous lust in his eyes.

"Okay, that's scary. I'm out." Oikawa said, turning away from him. "Gosh, he gives me chills."

"You haven't seen the real sirens yet." Iwaizumi said. "They're worse."

"I can't imagine." Oikawa shuddered, glancing over his shoulder to look back at Shoyo, who blinked at him innocently.

Yeah, he certainly couldn't trust people like those.

...

Shoyo stared at Oikawa, pushing against the glass. He didn't like this wall between them.

"Do you want to hear?" Iwaizumi asked, handing Oikawa a pair of headphones, which were connected to a computer.

"Is it safe?" Oikawa asked, taking the headphones from him hesitantly. "I don't want to die, okay?"

Iwaizumi rolled his eyes. "Relax, it's fine if you're not hearing it directly from him."

Oikawa scooted closer to Hinata, putting on the headphones.

"Woah."

His voice was... unnaturally melodic. It sounded so vulnerable and soft, yet so calming. It was the type of song where you could picture someone deep under the ocean. Mysterious, yet soothing.

Shoyo watched him expectantly, and Oikawa immediately took off the headphones upon realising that he was seriously getting sucked in.

"Can't take it anymore?" Iwaizumi teased, taking the headphones from him and putting them on.

"That is very dangerous." Oikawa said, gulping. "Very dangerous."

"His songs don't make you want to jump off a boat, but it certainly makes you want to go over to him." Iwaizumi said.

"Well, I actually might jump off." Oikawa admitted. "Iwa-chan, how are you not affected by this?"

"I've heard it a lot." Iwaizumi simply said. "It's quite calming, once you get over the luring effect. It annoys him a lot."

He motioned for Oikawa to look at Shoyo, who's gaze had hardened. He knew that they were listening to him.

"How old is he? Surely he isn't any older than 18?" "Mhm. Sixteen."