Sebastian was taken from his family in Tano from a young age, around 7, in the early 1990's. He was selected for candidacy in the program after displaying "Exceptional intelligence, above average physical form for his age and species, and above all else uncanny wit." He was brought to the Razgriz compound in the Jackson mountain range in the center of the country, where he was raised by Dr. Katelyn Frank, the director of the program, and Warrant Officer Michael Payne, the lead instructor.
Sebastian showed exceptional skill and utility during early years of training, proving a excellent marksman and team leader. He was expected, above most other of the 40 candidates, to pass augmentation due to his strong resolve and willpower. However, when augmentations (a second round of rigorous stem-cell injections after the early teen growth spurt) came in early 2000, Sebastian s immune system quickly showed signs of fighting the treatment. As a result, his growth began stunting instead of growing, threatening to trap the viable candidate in a teenager-sized body. Dr. Frank was convinced to stop the treatment and Sebastian was washed out of the program. The news hit him hard; believing he was meant to be a Razgriz operative and having been raised with the fellow candidates. However, he was promised a position that would "do him just as much service for his country."
At age 15, Sebastian was transferred as a undercover operative within the Naval Intelligence Directive of the armed forces. He was initially kept under close lock as a high-level asset; disclosing his presence (A fifteen year old would cause even hardened spies not aware of the Razgriz program to begin asking questions) wasn't possible. He worked several deep cover assignments before being transferred to being a traditional operative within the Directive at age 19, with a cover story to cover his true origins.
The young man was crucial to naval and national intelligence operations in the later Tano-Dveria conflicts, the District 58 conflict, the Vekaiyun and Valokchian civil wars among others. He is also a skilled marksman when needed, and among other tasks has been charged with taking down rogue Razgriz operatives.