Simon Tarses, the son of Marya and Tarvek Tarses, was born on the Martian Colonies in 2344. At the age of 18, Tarses joined Starfleet and attended the Starfleet Academy Training Program for Enlisted Personnel at the main Starfleet Academy campus in San Francisco. Following the completion of his training as a medical technician in 2363, Tarses was posted to the infirmary on Outpost Sierra VI. After several months on Sierra VI, Tarses transferred to the infirmary on Outpost Seran T-1. Following a year at Seran T-1, Tarses transferred to the medical facility on Ivor Prime in 2365.
Under the direction of Doctor Lu Chen Chow, Tarses assisted in isolating an alien prion pathogen that had caused an outbreak of transmisible spongiform encephalopathy on Icor IX. As a reward for his assistance, Tarses was promoted to Crewman First Class.
On stardate 43587 in 2366, Tarses was assigned to the medical division of the USS Enterprise-D. In late 2367, Tarses' Romulan heritage came to light following an explosion in the Enterprise-D's warp core. J'Dan, a Klingon exchange officer aboard the Enterprise, admitted to smuggling secrets to the Romulans. Because of his multiple contacts with J'Dan, Tarses was heavily investigated by a Starfleet board of inquiry headed by Norah Satie. It was discovered that Tarses was quarter Romulan, not Vulcan as established in his records, though it was determined he'd committed no other crimes.
In 2376, Tarses -- now a full MD -- was assigned to the infirmary of starbase Deep Space 9 under the command of chief medical officer, Julian Bashir. Doctor Tarses ran DS9's infirmary while Bashir was away on a three-month exploratory mission of the Gamma Quadrant onboard the USS Defiant.
By early 2381, Tarses was assigned as Chief Medical Officer of the USS Aventine under the command of Captain Ezri Dax. While the Aventine was investigating the wreck of the NX-02 Columbia, Doctor Tarses and a medical team had to investigate the horrific deaths of two engineering crewmemembers, Yott and Komer, killed for sustenance by a Caeliar who had hidden aboard the wreck for almost two hundred years. Although the scene was gruesome, Tarses had learned to suppress his gag reflex operating on cadavers in medical school. He also led the medical team that performed the investigation on a third death in the shuttlebay of the Aventine, determining them to be related.