It depends on who you ask. XD The Altonian emperor hates him because he steals his stuff and pawns it off. That may sound bad, but the proceeds from said pawning go towards helping people in need, many of whom have had their families murdered, crops stolen, villages ransacked, etc by the emperor and his cronies. I still need to develop the emperor's character, but at this point I can basically say that he's a sick SOB in charge of a dysfunctional monarchy that's crumbling around him, and all he cares about is his own pleasure.
That aside, on the D&D scale, I would consider my OC somewhat of a cross between chaotic good and lawful good. Lawful good, because he has a strong sense of justice and adheres strictly to the laws of his tribe. Chaotic good, because he has little regard for Altonian laws, but again a strong sense of justice and morality. He is what you could consider an ethical thief.
If you want sort of a far-fetched comparison, consider Dexter Morgan, from the series Dexter. He is a serial killer and a blood spatter analyst, but the only people he kills are criminals. He doesn't follow the law, but his morals are strong, and seeing as he works for the police, he most definitely has a sense of justice. The criminals he kills aren't small fry either; usually they are killers themselves.