The first time it happens, naruto is four and after a year of deafening silence in his lonely apartment, he was used to the quietness.
The ANBU changed shifts from Owl-San to Inu-San and immediately Naruto could sense something was off with the masked nin.
Naruto could feel how Inu-san's chakra was crackling heavy with more lighting than usual and something else that he couldn't place.
But the scent was what let Naruto know what was wrong.
Before Jiji gave him the apartment, he wandered the streets of the Red light district, and with his keen senses, he was able to take new scents and catalog them away for future reference. When he got to the bars, clubs, and brothels he smelled a scent that could mean danger for anyone not strong enough to defend themselves or it could mean money for certain individuals.
Lust.
That's what Inu-san's scent smelled like, mixed in with hounds, blood, and lightning.
The moment Inu-san's silent body slipped into Naruto's apartment and room, he knew what would happen, but he wasn't ready for the effects.
The masked nin made sure that Naruto was on his stomach before stripping him down of his clothes and when Naruto whimpered and pulled away he would respond with:
"Shhh, my little fox let me take care of you."
He hated that nickname.
After Naruto turned five, something happened. Still recovering from the mob that had beaten him a few days earlier, he was weaker than normal. The Anbu changed shifts again and Inu-San slipped into his room, but instead of immediately slipping onto his bed he paused and stared at the young boy.
"Who did this?"
The question startled him because the tone in his voice sounded like he was furious like what the villagers did was disrespectful to kami himself, oh the irony Naruto thought to himself.
Then the Anbu member slipped onto the bed, grabbing the boy's waist and turned him on his back. At this Naruto began to panic, Inu-san never had him on his back, why was today different?
As if sensing his thoughts Inu-San spoke, "I'm going to do something first my little fox, just try and keep still."
With that, Inu-San removed his porcelain mask and removed the black mask underneath to reveal the lower portion of his face.
Naruto gasped, the Anbu were never to reveal their face to anyone. His legs were grabbed and lifted to slip over Inu-san's so the Anbu captain could lay in between the boy's legs.
The masked-nin's hand came up to tilt the Jinchuriki's head to reveal his neck, once the blonde's neck was revealed, the silver-haired nin leaned foward and bit down a little above the spot where his neck and shoulder's meet adding some chakra to the bite mark ensuring there was scarring left behind. The action gained a cry out of the five-year-old and he started to struggle but his actions were slow and not as strong as usual.
The older man huffed in distaste at the boy's actions before flipping the boy on his stomach to take him once again.
Six months later his name was revealed.
Hatake Kakashi.