She took it better than expected.
"Rules?" he asked at first, looking quizzically at her. "Well, I am a Soul Piper. It is my job to guide the fallen souls of this plane onto the next, and if a soul was expected but its owner carried on living, in some way or another, it was my job to execute them so I could collect their souls."
He continued after a brief pause. "More recently, I've been given human form by my people. With that, I have human wants, and needs, like food. So I needed a new job, thus why I became an assassin. It only makes sense."
The man stared blankly at her, awaiting a response after he spoke of life and death so casually.