Elle Anderson is an agent with the CIA.
Our first contact with her has her in a ring sparring to keep in shape and in practice and very antsy to get back into the field. We are told that "Elle was intelligent, highly skilled in martial arts, an expert marksman, and excelled at ballroom dancing. She checked every box a modern spy could ask for and was psyched her sabbatical was over". In that sparring session, she shows from the beginning her determination to win and even more so, to not lose
We are also told that the phone call she receives afterwards offering her an assignment as "a freelance photographer" was the signal that her waiting was over: "She'd just been activated, and someone was going to die". That lets us in on what sort of work she did for the Agency. Anderson's work was called upon by the CIA when "things went genuinely wrong" as she was well aware that she was considered a "last resort".
Regarding that call about the photo gig, Anderson used as her official cover the role of photographer and to back that up, she had actually had some of her work published in legitimate publications like National Geographic and Newsweek. Back home in the two residences that she maintained, one in a city and one in the country, the few neighbors she knew always took her long absences to mean she was either at the other home or was away on an assignment. Not that it really mattered to Anderson; she had no one she was close enough to to warrant explanations.
When we first meet Anderson, she is an incredibly driven individual, willing give whatever it took to get the job done and insisting that others on her team be committed as well, although interestingly never demanding as much from them as she did from herself. As the action progresses, she will pay dearly for her devotion and will come out of it wiser but no less determined.
That team with whom she works so well with consists of :
Mike 'Tex' Traviano - a former Army Ranger from a large Italian family, and neither Mexican as their boss thought nor from Texas. He and Anderson have been together for three years and he feels he owes her big time for something in their past.
Jack Paulson - "a computer genius, handsome, and great with gadgets and gizmos but not so much people".
Eve James - "the quintessential girl next door: sweet, charming, adorable, and the best analyst on the planet".