Dusk seemingly comes and goes, just wandering through town without a care, yet also seeming incredibly saddened. Maybe she simply changes her mood with what seems appropriate at the time, but... she simply chooses not to show her true emotions. Anything she does could be just a cover up.
Unless you're talking about astronomy and the skies. This seems to be the only subject that causes Dusk to smile.
One speaking to her is rather odd, seeing as she never says a word. She instead simply uses magic to 'write' what she wants to say, like having a power point with her wherever she goes. Can she not speak?...well, she's not telling you, so to speak.