There were other vucari living in Segría already, but many of them were associated with the Cherskii mafia. Najat was recruited by these gangsters, but was not interested. Things got ugly, and Najat had to leave town inconspicuously after an over-eager recruiter was nearly killed in a scuffle. A local friendly Terrasan helped smuggle Najat out of town, and Najat, impulsively swore to oppose the gangsters and uphold the common Terrasans from then on. Landing briefly in Iclezza, he became a vigilante, but it was only by luck that he didn't get himself killed. Najat quickly determined that he was in over his head, and fled town again, this time to the wilds in the north.
In the Shifting Forest, he encountered other vucari, but they were unlike those whom he had grown up with. Xenophobic to a fault, they killed any Terrasan or other human who trespassed on their land; sacrificing captives to their idols of Selvans, the Horned God. These vucari accepted him, grudgingly at first, but they later came to admire his woodcraft and his knowledge of outside civilizations, which they could use in their own ongoing guerilla war to protect the entire forest from any encroachments at all.
Always naïve, Najat didn't see his knowledge being turned to uses that he didn't anticipate; he thought merely that he was telling interesting stories of his travels. A young chieftain's daughter even paid him a great deal of attention, and briefly Najat fancied himself in love. However, Najat was naïve, not stupid, and he quickly saw what was happening. He confronted his lover, and was heartbroken as he came to believe that she was only sleeping with him to wring all the information the clan could from him. Again, Najat ended up fleeing the forest at breakneck speed. This time, his talents were matched by those who pursued him, and he barely escaped with his life to the stockade of Fort Arval.
Najat finally understood that he needed to develop some discretion and possibly a bit of well-deserved paranoia. After fleeing for his life three times from three different locations in less than two years, he saw the need to reinvent himself. While still impulsive, idealistic, and eager to jump in with both feet in support of some cause, he's also tinged with a hefty dose of bitterness and anger towards those who he feels have wronged him over the years, especially organized crime. He feels torn between sympathy and revulsion at the vucari of the Shifting Forest, but he certainly learned a great deal of callousness as well as the effectiveness of a reputation for fast and overwhelming brutality at their hands. Dealing with Najat is a study in contrasts; while normally chatty and even almost charming (especially for a wildman, who are normally notable for their taciturn miens) his anger, when stirred, is notable for it's violence. His colder brutality, when he's not even angry, is scarier still.
Mechanics: Najat Chuluun is best represented in either Pathfinder or D&D as a ranger/barbarian. In d20 Past, I'd see him as a Strong or Tough hero who took on the Wildlord advanced class.