Avion is a very sweet and lovable person when you get to know her. She is/was a spy for Francis Conners, the owner of many clubs in France and is also a Senator, he offered both Avion and Milia a chance to be in the JL but Milia declined and so did Avion. Milia however told Avion that she had to go because the only reason that she’s staying is to finish a mission that she started a long time ago. Their boss made the decision that Avion would go and excused himself to go call the Justice League. She started arguing with Milia who in turn argued back, before Milia could comfort her she flew to her room and cried. She didn't know what to expect form a bunch of strange superheroes but she wasn't exactly whelmed. She’s going to be learning more than she bargained for.
Disclaimer: I own nothing but my own characters. Young Justice was created by Brandon Vietti and Greg Weisman.