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They really are a lot alike, but there is one difference. Steele tried to win Jenna over. Niju was never interested in girls.

I have to agree with this. They are far from being anything alike.
Niju wasn't a villan, he was just scared of change. Steele however had evil intensions, and cared only for himself, where-as, Niju seemed to actually care about the pack (If anything a little).

Looking back on this, I think it's reasonable to guess that Steele and Niju's similarities were largely rooted in patterns which persist simply because they work. For example, dark-colored characters tend to look more imposing (all other things being equal), three is a good round number for a band of lackeys or henchmen, and villainy hiding behind a mask of something noble (like trying to save kids or keep a pack from starving) will never go away because that's nearly always how evil works.