|Full Name:||Sebastian Chen|
|Age:||Late 20s/Early 30s|
|Occupation:|| CIA case officer|
Former CIA recruit at Camp Peary
|Portrayed by:||David Lim|
Sebastian is described as a focused and confident future agent. His nature is put to test as he meets new challenges through multiple CIA operations. How he evolves and faces confusion with regard to his moral principles and the actions he needs to take in the world of espionage will be a real test.
- He is Asian-American.
- He can speak and understand Cantonese.
- He is a highly moral and religious person.
- He is the fourth gay male character in the series after Elias Harper, Harry Doyle and Will Olsen.
- Due to his strong beliefs, Sebastian is in denial about his sexuality.
- He is a romantic interest of Harry Doyle.
- He is a former CIA recruit.
- After completing his training at Camp Peary, he becomes a CIA operative.
- In FALLENORACLE, it was revealed that his wife Carly Klapp used the cover of their marriage as part of an undercover operation with the AIC.
- In KUMONK, it was revealed that, he infiltrated the office at Camp Peary in order to find information that the task force collected so far. Sometime later, he ends up in a short physical fight with Owen Hall. After the fight is over, Sebastian clarified his role in exposing the names of the collaborators. By providing the necessary intelligence to the task force, their mission is considered a success. They expose the following names of the eight collaborators who were directly or indirectly involved in orchestrating the 2018 Hostage Crisis.