Nikolai 'Kolya' Ivanovich Petrov is an agent with the ECA.
That acronym stands for the Executive Covert Agency, a department in the American Intelligence community that few knew existed, which was exactly as intended. The fewer who knew, the fewer that could ask questions as its operatives followed the mandate set down in an Executive Order of the President of the United States. Those that did know of it knew what it was considered "the elite of the intelligence agencies" and that its Director, Margaret Bradford, answered only to the Chief Executive, hence the name.
Petrov had been with the ECA for the past nine years, coming to the then relatively new agency after working for another few years with the FBI; The ECA noticed him when he and his partner had made a huge bust of the Russian mafiya in Brooklyn. Though no specific age for Petrov was found by me, I estimate him to be at least in his mid-30s based on college, a few years in the Bureau, and then the almost a decade with the ECA.
His significant other is Alexandria - Alex - with whom he has lived for some time and been in love with for much longer. Theirs is a happy relationship though put through some major tests such as his frequent absences due to work. While Petrov is definitely the lead character in these adventures, Alex is nearly so as she plays not only important roles in the adventures, she is also the one tangible anchor Petrov has to hold onto in his mind when things go bad for him - and things go very bad more than once.
We learn on our first meeting him that he really disliked being a handler - or rather he hated the waiting that came with having sent another person into harm's way and then being able to do nothing further; "he preferred the active role, to be the one at risk".
When you take a look at the very unpleasant things about to happen to him when he is able to get his wish and become the actor rather than director, he likely would wish to reconsider things.