Described by Kobliad Security officer Ty Kajada as "quite brilliant in his own way," Vantika was obsessed with prolonging his life and ensuring his own survival. The life-prolonging substances he used included rejuvenation drugs, cryogenics, and organ transplant. As the chief medical officer of a high-security prison, he secretly used inmates for his illegal experiments in cellular longevity. As a criminal mastermind, he organized the theft of top secret bio-regeneration research. He evaded Kobliad authorities for over twenty years, faking his death several times (often in ways that fooled even medical specialists).
Like all Kobliads, he needed deuridium to stay alive, and was planning to hijack a shipment of ore arriving at Deep Space 9 from the Gamma Quadrant, when he was captured by Kajada in 2369. In an attempt to escape, he started a fire in Kajada's ship that killed the pilot and severely weakened her. His own body was also fatally wounded, but he had perfected a means of transferring his consciousness into another humanoid brain. Shortly before his body expired, he used the method on Doctor Julian Bashir, who had responded to Kajada's distress call.
Occupying Bashir's body, he attempted to carry out his original scheme. The transfer was discovered after a series of crimes aboard Deep Space 9, including an attack on Kajada. After Bashir was incapacitated, Jadzia Dax was able to transfer his consciousness from Bashir to a small containment field.
After Commander Benjamin Sisko formally returned custody of the "prisoner" to Kajada, she promptly destroyed the container, bringing a final end to Vantika's life.