Gaius Mikaru was a Sovereign of the Mikaru clan. He was not skilled with ship designs as most Sovereigns were but was a crafty business man and unparalleled combatant. He was eventually challenged for his rank when it was discovered he was siphoning family funds into his private accounts.
He would leave the clan after being Sovereign for 2 years due to these 'complications' where he joined the Sith Empire's ranks. As an Imperial Agent during the Great Galactic War He would serve the Sith Empire in many ways including espionage and assassinations. Due to his knowledge of corporate finances he was especially talented at infiltrating Republic businesses and siphoning funds to the Empire.
A skilled combatant Gaius used his mastery of the Echani Martial Arts to overcome opponents and a latent but unrefined Force Sensitivity would aid him many times in the manner of a sort of Sixth Sense. Though Force Sensitive he was not a candidate for training as a Sith due to the lack of potency in his sensitivity.
He would be remembered in the Mikaru Family Linage as "Gaius the Betrayer" and would eventually appear to Vincent the First on Korriban a few years after the battle of Yavin, though it was in actuality a Sith Spirit attempting to tempt the young Echani to the Darkside.