The essence of ethics is a description of more or less just human relations.
The 4 natural relations, in the order of increasing nobility, are hostility, equality, hierarchy, and complementarity.
The additional relation enabled by divine grace is charity.
I use the natural law ethics that builds on Mises and Rothbard, along with a comprehensive big picture of what exists, to illuminate many of the long-standing issues in metaethics, in particular:
The semantics of moral terms; the metaphysics of ethics (such as to what, if anything, these moral terms correspond); the epistemology of ethics or how we come to know our duties; anti-Humean duty-driven nature of morality; moral objectivity; moral internalism, and a ton more fun stuff!