User blog comment:DE-Note/What Determines the Strength of One's Aura?/@comment-25405817-20150529021858

I believe the quantity of Aura of a single individual is based on the purity of their soul. Or more especifically, their simplicity.

"Victory is in a simple soul."

A person with no qualms, insecurities, or negative emotions that could stain their souls are bound to have bigger Aura reserves.

Jaune has been stated to have a lot of Aura, and it has been seen in the actuall show. He did challenge Cardin, but not because of hatred, but because he stood up for his friends. He even has said that he doesn't resent Cardin's bullying because "He's a jerk to everyone". Jaune is what is known in Troperville as an "All Loving Hero". He won't hate you, but will stand up to you if you cross the line.

And about Ruby... meh, she's a Mary-Sue at the moment, so she gets away with it for no reason.