Naruto's new father is a Merman

3

A tick mark appears on the man's forehead at the boy's ability to drool all over Hiro's torso. Other than the drool, Naruto was in pure bliss, he'd even smiled a few times in his sleep, the blue-haired male wonders what he dreams about. The only dreams the man dreamt about, were the reoccurring single dream, he continued to have all his life. The one about the laboratory, where he and many others were created as a fun experiment, it was enough to be considered a nightmare, but he long stopped whimpering in his sleep. He lives a long life so it was inevitable, to one day happen, where he'd stop being a coward and take it like a man.

Hiro was maybe a few hundred years old, maybe it was due to the experiments made on him that he stopped aging at one point. He felt like a monster that couldn't even claim to be human, nor fish, because most fish and humans die when they are too old and simply can't live on. But he didn't have the pleasure of dying, even when he should've died, after being torn apart into pieces by a shark, as a small six-year-old. But to his fascination and horror, his body regenerated itself and he kept living, never dying. He was trapped. He was immortal.

Naruto fidgeted, his snores emitting, loud echoes throughout the cave, rolling around to use the blue-haired man's thigh as a pillow, Hiro has a twinkle in his eyes and smirks. It was time for him to get up, he'd found the boy thrown out on the ground in the forest, he thought to himself this boy is pathetic. His skinny, malnourished, body gave out on him, and if he left him there he'd surely die.

FLICK!

"Ahh!" Naruto springs up from his position, clutching his forehead in pain, giving the man a questionable look beside him. "What was that for!!???"

 "Get up, and stand over there." the man orders, ignoring his question, and points in a direction. Hiro stood up with no warning and glares at the small body, that flopped down on the ground, because of him. 

Naruto stares at the open space of the underwater cave, it was a clearing next to a large pool of water and he didn't want to find out, where it led to. Fearing, if he went next to it, Hiro would kick him in with no remorse, and leave him there, struggling for his life. Gulping, Naruto relaxes nerves, it's not like he's going in the water anytime soon, haha. Oh, how wrong he was...

Hiro follows him to the clearing, standing a few feet away. "Let's fight I wanna see how weak you are," seconds pass by which turned into minutes, the man stares at him intensively, lowering himself into a weird, but practiced fighting stance.

"I'm sorry...What?" Naruto thought this man is insane, why would he fight someone obviously much stronger, does he think that he is that stupid!? "I think I've misheard yo-"

Without another second to lose, Hiro charges after him and punches the boy in the face, sending him into the cave wall. There was a satisfying crack resonating, the blonde boy is sure one of his bones was broken. 

Gritting his teeth, Naruto's instincts shouted at him to move and he did, dodging a soaring kick from above. He was lucky to come out alive, but the wall was not as lucky, in place of him was a large crater with crumbling rocks. Barely crossing his arms in time, to block another punch, he scolds himself for getting distracted. Naruto scraped the bottom skin of his feet skidding back further down the cave ground.

Everything hurts, Naruto couldn't feel his right arm anymore, at this point if he doesn't land at least land a hit, Hiro will just kill him. He had to pass this trial. Naruto dashed forward aiming his fist at the blue-haired man, the man grabs the outstretched arm, swings, and slams the boy into the floor. Hiro walks over to the boy embedded in a small crater that fits the boy's body, he appears to be unconscious.

 'How pathetic' the man thought, 'That was less than 30 seconds,' Hiro reaches down the hole to grab the battered small arm of the toddler. 'There is no way he survived thi-' a cloud of smoke appears and the man waves it away, revealing an empty hole, his eyes widen. An incoming attack from the rear, how predictable, he wrapped his hand around the small wrist stopping an immature punch, he gutted the boy in the stomach. 

The blonde boy retches, stomach contents spilling out, collapsing on himself, clutching his stomach. Liquid continued to pour out alongside blood. He felt lightheaded...dizzzy....he wanted to sleep away the pain. The approaching footsteps of bare feet, stop in front of him as if mocking his pathetic figure, how weak he was. Naruto wanted to prove himself, but moving even a millimeter had him curling into himself more, the pain too much to bear. 

"Have you finally given up?" The low husky voice of Hiro tickled his ears, fingers curled through the boy's hair yanking his head up, to face the man's blue-almost-black eyes, his abdomen wailing out in torment at the sudden movement. Naruto clenched his teeth, holding back his cry of agony, his vision blurring, the black spots appearing. "You haven't done much at all, and you're already giving out."

"H-hiro san, please...-", Naruto choked out, he knew he disappointed Hiro greatly and possibly failed his trial, "I'll be a-anything you want, do w-whatever you want, b-but p-please don't k-kill me."

"A trial is a trial boy and if you can't display strength then-" A rough but smooth hand wrapped around Naruto's neck, the boy desperately trying to pry off his hands to no prevail, he was lifted off the ground. The man walked over to the pool of water, "You'll have to swim your way back to the surface with weights."

Without a second to waste the man's fingers, gracefully wrote seals on the boy's ankles and forearms. And Naruto was thrown down into the depths of the water, struggling to latch onto a ledge but it was futile, the movement only made him sink more. It's only time that he'll breach past the limit, humans are known to stop before. Any lower than that he'll die from the pressure.

Hiro brings up his wrist and slices it open, a dark magenta flows out and down to the water like a faucet, permeating the surface, and he did a boar sign, "Moon of Rebirth," 

The water flashed bright and turned completely dark magenta, and started boiling.

"He better pass the trial, otherwise, the ritual will prove him unworthy, and kill him," The man murmured softly, crouching down next to the water hole and waiting patiently. Hopefully, for his sake, he does not die. But who knows exactly, right?