Before getting hired by Ryn, Zior fought for the Rebel Alliance. He was a very gifted fighter pilot and was also very arrogant. After the galactic civil war came to an end Zior saw little reason to join the New Republic as a fighter pilot. He wanted to act more freely and didn't want to go where the fleet admirals told him to go. Seeing that beeing a pilot for Ryn was a good way to continue to help maintain galactic peace while keeping himself relatively independent he signed on with Ryn and his crew.