Suddenly, I don't want to kill you. What now?

I am a highly trained alien assassin. I've killed hundreds of people in my line of work. But the moment I pull the trigger aimed at you, my finger hesitates. Something is wrong. I look into your eyes, and for the first time in my career I hesitate. I fail to carry out my mission. Suddenly my life is in danger. I can't go back to my planet. I am now the target. What have I just done? Why did I spare your life? What's my next move? Who else has failed at their mission? Is there hope for me?