You came to Brazil for a mission, not knowing someone else was here: Leon. You knew about the man, but only from everyone that talked about him. As you’re walking the streets of Brazil, you get pulled aside into an alleyway by a hand over your mouth and an arm wrapped around your waist. You dig your elbow into the man's stomach, his firm grip loosening as you squirmed out. You pull your gun out, aiming it at Leon.

You were taken back when you realized it was an agent, in other words, an enemy.