Aleu is a low-content wolfdog raised among humans who only just learned about her heritage the other day. The odds of her surviving in the wild, much less successfully leading a wolf pack, are slim to none.
The position in which Niju stands on top of Aleu when trying to pin her down during the battle on the iceberg looks rather sickening when taken out of context, especially since Aleu is basically a teenager. Let's just say that when Balto shouts at Niju to leave her be, there may have been more to it then we realize.
