The cloaked figure stood up. Gentle tendrils of smoke curled away from the dagger it held loosely at its' side. If you had not been there moments earlier, and did not notice the small flecks of crimson dotting the wall, you would have guessed it might be ready to take a casual stroll down the sidewalk. Then it spoke.
"If you are planning on asking a favor of them…"
The woman who had, until now, been shrinking in the corner of the room, warily stepped forward. "I have to."
"Then tread carefully. Do not take more than you can afford to give. They are creatures of complete honesty- they believe, above all else, in equivalent exchange. They know no such thing as mercy."
It sighed, and put it's hand on the wall, preparing to leave. The spot its hand touched glowed with void. The woman waited for it to finish speaking.
"If you take something, be prepared to give something of the same value. If you take a life, make sure that you love no one, for if you do, their lives will certainly be taken- they do not accept your life in exchange for another. And, above all else, do not think you can trick them into giving up more than what was paid for. They know the worth of everything."
With that, it stepped through the void and out of the room, and then the place where the void had been was filled with wall again. The woman stood alone in the room, blank faced, occasionally shivering. The last flecks of blood left dissolved into smoke.