User blog comment:DE-Note/What Determines the Strength of One's Aura?/@comment-10380701-20150529003752

Jaune's is not the strongest. He just has a lot.

I assume it's a superpower lottery. You can end up with over 9000 aura levels, or be unlucky and just get 20.

That's not counting aura training, which may likely make it skyrocket.