T'arus is a Vulcan assigned to the to the Directorate of Clandestine Services (DCS) division of Starfleet Intelligence. DCS operates as the clandestine arm of SFI (not to be confused with Section 31), and serves as the authority for the coordination, deconfliction, and evaluation of clandestine Intelligence operations across the Federation. The DCS also conducts counterintelligence and special activities as authorized by the President of the Federation. The DCS supports the United Federation of Planets’ security and foreign policy interests by conducting clandestine activities to collect information that is not obtainable through other means. (Star Trek: SFI)
T’arus is a field operative who is friendly to both Nick Spencer and Jack Nolen, but frequently at odds with them both. T’arus is a bit of an enigma to Humans. It is not unusual for people to question where his loyalties lie. T’arus joined Starfleet with the blessing of both his family and the Vulcan Science Academy. He has been working in the field for over 50 years and knows much more than he tells.