Personality:
If asked to describe Kuroi's personality in a single word, most of his acquaintances would certainly choose the word "misleading" as soon as possible. That being said, the why for this quick choice of wording isn't exactly mysterious even for anyone that manage to forcefully interact with Kuroi until the true self of the man appears, as the behaviour of the young-faced jounin isn't nowhere near what one would expect from his dark choice of clothing and constantly emotionless face, being, in fact, the exact opposite of what his face constantly displays: Mischievous, easygoing and surprisingly fun-loving, Kuroi has a natural disposition towards being friendly with pretty much anyone that ignores his stern facade and starts to talk with him, being an individual recognized by his sarcastic humour and carefree remarks - both conveniently said with the same emotionless voice as always, often making others confuse his intentions.
In truth, Kuroi doesn't really try to hide his emotions, but rather is unable to effectively display his feelings through his voice and face - a fact that brings quite the amount of depression to the inherently sociable jounin, that even when making his utmost effort can't make any expression other than an uncomfortable grin that appears to be so overwhelmingly arrogant that makes even his personal friends doubt about the intent behind it - and due to that he prefers to hide his sociable nature as a way of preventing hurting others through his sheer inability of displaying what he really feels, considering the act of hiding his true self the best solution to his predicament.
In despite of that, Kuroi's emotionless act never managed to hide the truth from the higher ups of the village: He does, indeed, love Hikaemena and all the peace it brought to his life and often considers himself to be in debt with the village, hardly thinking twice before putting himself in dangerous situations for the safety of his loved home. No need to say shares the same deep loyalty for those he considers as true friends, recognizing their willingness to accept him as a demonstration of affection that he can't possibly repay in a single lifetime.
History:
IntroductionThe Shinobi world was never a caring and compassionate one, with many focusing on war to grow stronger and even more facing demise through their hands, this merciless world never missed those who would do anything to attain the strength needed to impose their ideals and, for better or worse, the man now known as Kuroi was born from the madness of one of these individuals.
Infancy/CreationBorn not from the love of two individuals but from the madness of a single criminal, Kuroi is the result of multiple experiments made in the attempt of creating a genetically engineered army of Shinobi with the perfect constitution for practicing the way of the Shinobi - stronger, more durable and possessing an inhuman chakra capacity boosted by their even more absurd recovery, it was obvious to their utterly mad creator that, if his experiments worked, nothing would stand in his way after the growth of his "beloved children". Fortunately, that didn't happen.
From the 216 subjects of the mad criminal ninja, only a single child managed to survive through the continuous experiments and harsh training to reach the age of 8: Subject Kuroichi.
Being one of the earliest subjects prepared by the missing-nin and the first of his series (dubbed as Black series), Kuroichi was considered a failure even after being the only one to survive: His genes were simply too weak for his creator to make use of, without even being able to awaken the Kekkei Genkai carried by his "father's" clan, the subject was immediately disposed of as nothing but a failure, being left to die in one of the multiple battlefields of the small country that he came from, surrounded by bodies and cursing the world as he slowly died from grievous wounds caused by his own creator, that his regeneration continuously tried to close.
When asked about his past many years later, Kuroi would often skip this part as a whole due to the nature of what happened next, as the gruesome nature of his following act: He used "his" Kekkei Genkai for the first time to desecrate the bodies of fallen Shinobi, consuming them through the use of his bloodline to heal and nurture his body before running away from the gruesome scene while following his instincts that, unknowingly to himself, guided him to the place who acted as home for the creatures that would take care of him for the following 10 years: the mythical Ryūchi Cave.
Ryūchi CaveEven if asked today, Kuroi wouldn't know exactly how many days he passed running through uncivilized areas, desperately relying on his instincts to distance himself from the place that brought him so much pain without even caring about where he was going to. Maybe thanks to that he managed to find the way to the ancestral origin of his bloodline through sheer instinct, some unknown impulse or maybe utter luck - only a god would have the answer for this question as, even today, Kuroi has no idea about how or why he managed to reach the caves.
Even as a wounded and afraid kid, Kuroi could feel the strange sensation of familiarity coming from the caves when he first saw their ruin-like entrances, something calling him from the depths of the mythical place, something that he instinctively decided to follow without even thinking twice, being guided by the mysterious impulse until reaching the figure that would change his fate: The White Snake Sage. Until today, he doesn't know exactly why the sage accepted him and granted him his bite, but one thing is for certain: In the profoundly hidden ground of the cave, the young boy found for the first time a true home amongst the silent inhabitants of the place: the snakes.
For the next eight years the boy lived as one of the mythical snakes of the cave, learning the way of the snakes and accepting his place amongst them just to face a sudden crisis in his sixteenth birthday: It was time to return to his own kin. He didn't - and still doesn't - understand why he needed to return to the kin that had abandoned him before, but under the coercion of the White Snake Sage, he had no choice other than leave the caves and travel the world while accompanied solely by a single infant snake that volunteered to accompany him.
The travelling and a new home