Ethan Blake is an agent with MI-5.
That statement is a bit of an exaggeration, at least initially, but it will come to be the case, mostly.
When we meet him he is a 17-year-old young man who is admitting to himself that now that he was wondering what he was going to do with his life. As the short synopsis in his first recorded adventure states, "Driven by a fierce determination to make something of his life, Ethan will push himself to the limit, face his fears head on and stand by his friends no matter what. Skydiving is just the opportunity he's been looking for, and he doesn't want to be simply good, he's out to be the best. Period."
It was late in the evening when Blake was talking a walk in his neighborhood to clear his head that he hears a yell and sees someone fall from the room of the block of flats. Stunned to see a man fall to his death, he is even more stunned to see a small chute open up and the man land near him. When Blake expresses his amazement, the man explains in quick words about B.A.S.E. jumping and "You do skydiving first, then this - same deal, less room for error." When asked why he did it, the man says, "Life's too short not to."
This was the bizarre way Blake is introduced to a new sport and a new excitement and why he would seek out lessons in skydiving and how he would end up with a group led by Sam, a "world-class skydiver, skilled undercover operator, and exceptional soldier" who had to put together a small team of skydivers for a mission for MI-5. He was one man short when he meets the eager Blake.
Blake has no idea what he is literally and figuratively jumping into.