"Do not neglect to show hospitality to strangers, for by this some have entertained angels without knowing it."
-Paul's epistle to the Hebrews, chapter 13
Mercurians have a resonance for human relationships, which they can supernaturally perceive at a glance. Even a young Mercurian is likely to have a better grasp of humanity than more senior angels of other Choirs.
It is dissonant for a Mercurian to harm a human. They don't suffer dissonance for letting others harm humans, but it grates against their nature to do it themselves.
Mercurians do most of their work on Earth, as one might expect. Just about anything that requires dealing with humans, especially groups of humans, can benefit from the attention of a Mercurian.
In celestial form, Mercurians appear much like the standard Western conception of angels: humans in shining clothes with halos and feathery wings.
- Mercurians are all cheerful, attractive twentysomethings.