Dustil Onasi was the son of Carth Onasi. He was taken by the Sith during their invasion of Telos and sent to the Sith Academy on Korriban, where he nursed his anger at his father for not being there to protect them from the invasion.
Carth eventually found his son and was able to convince him (with the help of Revan) to leave the Academy and return to the Republic.
