Note: the Black Star Courier is an OC of mine technically speaking. She's... not actually human. "Canonically" she always wears a rebreather. That's mostly to deaden her intensely sensitive sense of smell, as it gives her sensory overload. Also she's got sharp pointy teefs - so it hides them too.
She's best summed up with what I thought of when I made her:
"Sorry to be the bearer of bad news... silver lining though? I solve problems in my spare time, and my schedule just opened up..."