Those who could walk the sky, known as ozyly-esehembo in the primary Chiss language Cheunh (which directly translates to "sky-walker" in Galactic Basic Standard), were Force-sensitive navigators of the Chiss species. These individuals were vital to the Chiss Ascendancy, assisting them in traversing the perilous hyperspace conditions found within their native Unknown Regions of the galaxy. Within the Ascendancy, sky-walkers served both the military and diplomatic corps through organizations such as the sky-walker corps, and later, the seekers program.
The Chiss Thrawn once expressed his bewilderment upon encountering Anakin Skywalker, who bore a similar name, during the Clone Wars. This occurred after he requested that Darth Vader utilize the Force to guide the Chimaera. Typically, sky-walkers were children of the Chiss species, almost exclusively females, generally aged between seven and fourteen. However, as recalled by former sky-walker Mitth'ali'astov, their abilities could sometimes persist until the age of fifteen. Conversely, these powers could also diminish prematurely, as experienced by Thalias herself, who lost her abilities at thirteen. In one rare case, the ability was retained until the age of twenty-two.
At a young age, Ozyly-esehembo were separated from their biological families and were not considered members of any Chiss family while serving in the Sky-walker corps. Nevertheless, many Ruling Families within the Chiss were eager to adopt former sky-walkers, viewing it as a prestigious honor.
Caregivers, typically women, were responsible for looking after the sky-walkers. A century before the Nikardun conquests, all caregivers were former sky-walkers. However, by the time of the Nikardun conquests, very few former sky-walkers returned to care for younger sky-walkers. Mitth'ali'astov, who served as Che'ri's caregiver, was one such exception. The Ascendancy maintained strict secrecy surrounding the existence of ozyly-esehembo, revealing it only to high-ranking civilian and military personnel. In the Fleet, only bridge officers and those of higher rank were informed, while lower-ranking individuals were falsely told that the ozyly-esehembo was the captain's daughter.
Sky-walkers employed what they termed Third Sight to navigate the treacherous territories of the Unknown Regions. This ability drastically reduced travel times, condensing journeys that would typically take weeks into a matter of days. A Caregiver always accompanied each sky-walker. Upon the fading of their Third Sight, many sky-walkers were adopted into prominent Chiss families of the Chiss Ascendancy as merit adoptives. Once their Third Sight was discovered, sky-walkers were taken from their families for training. Kivu'rik'ardok, the elder sister of Mitth'raw'nuruodo, a Chiss officer, was taken to become a sky-walker at the age of five. Some sky-walker training took place at the Expansionary Fleet Complex located on Naporar.
When it was suspected that sky-walkers were losing their gift, the Ascendancy would administer tests. Some sky-walkers possessed a rarer ability known as Second Sight, a form of telepathy. Chiss officers and warriors held their sky-walkers in high regard and reacted negatively to diplomats or other officials who belittled their navigational abilities. Pilots, in particular, worked closely with the children and often developed close bonds with them.
Eli N. Vanto, a human officer, was entrusted with codified data concerning the sky-walkers by Mitth'raw'nuruodo "Thrawn" and Admiral Ar'alani. His mission was to decipher the secrets of their powers, with the hope that his research could reveal how Vah'nya managed to retain her abilities until the age of twenty-two.
Timothy Zahn, the author, disclosed in a September 1, 2020 interview with StarWars.com that the development of the Chiss Sky-walker Corps as a significant aspect of Ascendancy society was unintentional. Initially, he created the ozyly-esehembo "sky-walkers" as an homage to the name of Anakin Skywalker/Darth Vader, the Jedi Knight/Sith Lord, for Thrawn: Alliances, without intending for it to become a major element of Chiss society. However, when he was offered the opportunity to write the Ascendancy Trilogy of novels detailing Thrawn's origins, he was bound by the name "sky-walkers." Having established the necessity for Force-sensitive navigators to safely traverse the Unknown Regions, Zahn expanded upon this concept to develop the Navigators' Guild and other groups of Force-sensitive navigators within the Chaos. Zahn expressed his desire to strike a balance between developing the Chiss culture and other Chiss characters on one hand, and showcasing Thrawn's prowess on the other, in the series that began with Thrawn Ascendancy: Chaos Rising.