Do celestials ever get tired? Feel extremes of temperature? Get sick? Are they affected by drugs?
No, not really, no, and sort of. (I’m sure a certain unstoppable rabbit-vessel is a demon in disguise, for example.) As a rule-of-thumb, celestials are unaffected by temperature down to freezing and up to 100F or thereabouts. Beyond that range they have reduced sensitivity when compared to humans. They can feel the temperature, but it doesn’t particularly damage them – they don’t get heatstroke, or suffer true chills. Celestials are unaffected by corporeal diseases (but apparenlty can contract certain diseases designed just for them; this was one of the projects of the Prince of Disease). This also means that celestials cannot be “carriers” in the classic sense of the word, but if one were doused in a bubonic plague culture, someone could be infected from the germs on the outside of the celestial’s skin or clothing. They are, however, affected by drugs but typically have higher stats and withstand the effects better.