The 49-year-old actor admitted that before diving into the role, he discovered a striking fact about the agency’s operatives: many field agents, and double agents in particular, are absolute sociopaths.

"I spoke with a few people from the CIA who were very helpful in clarifying certain things for me. In the end, I came to the conclusion that Martian is a sociopath," Fassbender shared in an exclusive interview with PEOPLE magazine. "That’s why he’s so damn good at his job. I realized he ticks a vast number of boxes for being a sociopath, and for that line of work, it's actually not a bad trait to have."

Fassbender’s character is intelligent, calculating, highly perceptive, and masterfully manipulates people to achieve his goals. In the season one finale, when Samia (the woman he loves) is kidnapped, he turns against his own government and leaks classified intelligence to save her life.

Fassbender is convinced that only a sociopath is capable of the actions Martian takes. "He doesn't hesitate to put others in mortal danger," the actor explains. "There was a point where we tried to show that he retains remnants of his humanity through his relationship with his daughter and his love for Samia, but in this story, there is a literal battle for his soul."

The actor also mentioned another detail he learned from insiders: many double agents struggle with alcoholism or substance abuse. However, he chose not to write those traits into his character.

"He isn't a drug addict, and he isn't an alcoholic," Fassbender says. "But he is addicted to the game itself. And this season, when we see him back out in the field, he returns to his natural habitat—the place where he is most comfortable."

Season two of The Agency is now available to stream on Paramount+.