Fortune-telling doesn't reveal the future; it mirrors the present. It resonates against what your subconscious already knows and hauls it up out of the darkness so you can get a good look at it.
I'm not...' Angharad began, but then she thought. Not what? Not a bad person? Perhaps. But had she never known anger? Never held unkind thoughts? The stranger's observation was valid. No one was innocent of darkness.