Veteran of the Clone Wars and a respected warrior, Fenn Rau led the Protectors of Concord Dawn with a combination of honor and ruthlessness. During the Clone Wars, he served as a flight instructor for the clone army and fought in many clashes, including the Battle of Mygeeto. After the rise of the Empire, however, he accepted payment to act in service of the Imperials. It was not until he met with -- and was captured by -- the Ghost crew's Kanan and Sabine that he came to align with the rebels.
Held in a rebel cell, Rau still refused to join the fight against the Empire. But when contact with the Protectors of Concord Dawn was lost, he volunteered to investigate with Sabine, Ezra, and Chopper. They arrived to find the planet half-destroyed, all his men killed by Imperial Super Commandos -- Mandalorians loyal to the Empire, led Gar Saxon. He came to see the ruthlessness of the Empire, and ultimately saved Sabine, Ezra, and Chopper from the Mandalorians. Impressed at their devotion to their cause, he finally agreed to join the rebellion.