By the year 5 BBY, the human Cassian Jeron Andor had embarked on a search for his long lost sister Kerri, whom he had not seen since she was six years old on their homeworld Kenari. When the young Andor, at that time known as "Kassa," had joined an expedition to a crashed Galactic Republic transpo corsair, he was separated from his group and taken off-world by Maarva and Clem Andor to protect him from an incoming Republic force, which led to his adoption into the Andor family and new life on the planet Ferrix. However, Cassian felt like he had abandoned his sister and was filled with guilt, particularly after a was said to have wiped out all life on Kenari during the Imperial Era.
Andor crossed back and forth the galaxy in search of Kerri. In 5 BBY, Cassian, having discovered a lead on a Kenari girl working at the Leisure Zone brothel on the planet Morlana One, traveled to brothel but discovered from a hostess that the woman in question had departed months earlier. Cassian's mission also brought him into conflict with Kravas Drezzer and Verlo Skiff, who both ended up dead at his hands. The incident caused a knock on effect that brought Cassian into the crosshairs of the Galactic Empire and early rebel movement. Following the Aldhani heist, Maarva advised her adoptive son to stop his search for Kerri, reminding him nothing was his fault and noting that his sister had more-than-likely died. Cassian, however, refused to respond. After losing Maarva to her old age and following the uprising on Ferrix, Cassian would join Luthen Rael's cell of the early rebel movement.
Tony Gilroy stated that Kerri's disappearance serves to set up the idea of Cassian Andor losing people and leaving them behind, which was particularly important to season two.