Carth Onasi, nicknamed Fleet, was a famous Human male soldier and an expert pilot born in 3,994 BBY on the planet Telos IV, where he would start a family with his wife, Morgana, they had a son they named Dustil. He served in the Republic Naval Starfighter Corps, fighting for the Galactic Republic he loved above all else in such conflicts as the Mandalorian Wars against expanding Mandalorian clans, earning several honors for his bravery during combat. During the war, Onasi served under Admiral Saul Karath, who would become his greatest ally and mentor. After the the war's end, Onasi planned to leave the Navy and return to Telos to be with his family.
However, such plans were put to an end when war heroes Revan and Malak, two Jedi who had decided to fight in the war, turned on the Republic, becoming Sith Lords while taking many Jedi that had followed him to war and the Republic soldiers who served under them with them when they created a Sith Empire that would oppose the Republic. During that conflict, Telos was attacked by Karath—who bombed the planet from his flagship, Leviathan, until it was made completely uninhabitable so he could prove his loyalty to the Sith. The orbital bombardment killed Morgana while Dustil, being Force-sensitive, was abducted by the Sith so he could be trained as a Dark Jedi. Onasi swore to seek revenge against Karath for the death of his family and the destruction of his homeworld; he would hold that grudge for three years.
At that time, 3,956 BBY, Onasi played a crucial role in the search for the Star Forge, the Sith's super-productive space factory that continually fed their fleet new ships. He was stationed aboard the Hammerhead-class cruiser Endar Spire over the planet Taris when it was attacked by the Sith, now lead by Malak after he had usurped control from Revan. The former leader was then reprogrammed by the Jedi and made to forget his time as both a Jedi and a Sith before being placed in the Republic's armed forces aboard the Spire, where he met Onasi as the two were both fleeing the doomed ship. They temporarily settled on Taris while searching for Jedi Knight Bastila Shan, the only other person known to survive the attack on the Spire.
After finding her, the three fled Taris and Onasi would serve as the pilot of the Ebon Hawk, their personal starship, transporting the trio and a growing group of allies across the galaxy as they searched for Star Maps that would lead them to the Star Forge, a mission given to them by the Jedi Council. As they traveled through the stars, Onasi was able to both find his son, who was then turned from the Sith ways by Revan and his father, as well as enact his revenge upon Karath, whom the group killed aboard the Leviathan. Once the Forge was located and destroyed during the Battle of Rakata Prime, Onasi was made an Admiral in the Republic Navy, taking a leading role in the effort to help the Republic recover in the wake of the two subsequent wars. To this end, Onasi would later defend Telos from another Sith attack during another conflict that would stem from the Jedi Civil War Revan and Malak began almost a decade before.