At first, Lev comes across as quite a spoiled, entitled character. His status as a tithe has given him a smug sense of superiority over others. Yet Lev's holier-than-thou attitude is wholly misplaced. Due to his upbringing—or brainwashing, as you might prefer to call it—he has no understanding of the inherent evil of the unwinding process. As such, he's puffed up with pride at being a tithe, and looks down upon the Unwinds, or "the terribles" as they're also called.
Over the course of the book, however, Lev acquires more wisdom and street smarts. He begins to realize the true nature of what unwinding really involves and how it destroys lives. As well as becoming more courageous, Lev starts breaking the rules, becoming ever more defiant of the accepted social norms. No longer naive in the ways of the world, he develops quite a cynical side to his personality, becoming in some ways rather an unattractive figure, as can be seen when he tricks a trader over a diamond bracelet.
Nevertheless, Lev's experiences as an outlaw don't completely hollow out his soul. He's still fundamentally a good young man, who wishes that his parents could take care of him once more, only this time properly. He also joins with Pastor Dan in expressing his wish to believe in a God who doesn't sanction the barbaric practice of unwinding.