Background
Jer was only 16 when the CIS invaded Ryloth. Although young, he was quick to take up arms against the invading forces and join the the Twi'lek resistance, led by the legendary Cham Syndulla. Because of his age however, he was placed away from the front lines and was assigned to marksman duty. As a result of this, Jer became skilled in marksmanship, as well as utilising the environment to his advantage.
After the collapse of the Republic and the rise of the Empire, Jer continued to fight for Ryloth. Jer refused to believe the Jedi ever betrayed the republic and he saw the Empire as nothing more than another force of evil.
After the Battle of Yavin, Jer knew the Empire's days were numbered and decided to leave Ryloth and join the wider Rebel Alliance.
Motivation