Kyon was a male Codru-Ji born on Munto Codru in 35 BBY to Pithkron and Kymith. He was an Inquisitor trained by Antinnis Tremayne. He stood 1.75 meters tall and massed 75 kilograms. He had white eyes, brown hair, and tan skin.
In 18 BBY, Kyon successfully hunted down a number of Jedi children and their protector, who had fled Belsavis, to a station. While Kyon engaged the Master in a lightsaber duel, Rothem and Mickey arrived and killed five of the children. Kyon initially thought Rothem was a parasitic insect and swatted him. Mickey and Rothem then killed the Master and one remaining child, and the remaining two children escaped Kyon's clutches only to be intercepted and killed by Pescado. A supporter of the Jedi then used an insect-like microdroid to inject a dart into Kyon's arm that delivered a debilitating electric charge, but Kyon survived and killed the man. Kyon and Pescado then introduced themselves to each other and to Mickey and Rothem.
In 17 BBY he helped Darth Vader hunt down and slay Jorro in the sewers of Coruscant, though Jorro managed to wound them both.
At one point, Kyon Force-choked a sentient plant, a salesbeing who was trying to rip him off while on Asylum Station. Procurator Hethrir regarded Kyon as usurping his authority and dropped a Hutt on him.
On a mission to Korriban, Kyon was attacked by a swarm of venomous insects and received a poisonous bite.
Kyon led a mission which destroyed Mama's Fruitcake. He also helped caused a flood on Sullust.
In 13 BBY, Kyon accompanied Agents Rothem and Pescado, as well as Imperial Advisor Bobatine, on "diplomatic" (i.e., espionage) missions throughout the galaxy. One one such mission they took down the planetary shields of Hellenes Gracca so it could be taken over by the Empire. He was awarded a Medal of Diplomatic Accomplishment.
In 2 BBY, Bobatine, Kyon, and Rothem visited Wilhuff Tarkin's station over Omwat. They witnessed the deaths of Zorith and Ambrose Ius.
Kyon had a cybernetic right arm. At one point, a cyberneticist installed a compartment in the fake arm which housed a miniature battle droid. Kyon's flagship was the Jedicide. He owned two lightsabers, one red and the other black, as well as a lightwhip.
Kyon could build vehicles and was a skilled fleet tactician. He could speak Codruese, Basic, Ancient Sith, and Classical Ossan.