All of which means you need to know not just what your non-human wants in plot terms, but why he wants it. You can teach yourself the answers to that by asking yourself some basic questions. Start with the nature of the magic itself. Let's assume for now that the society is magical. Bear in mind that if magic is real, then it will affect every aspect of life in the society in some way.
Every human society has rules of some sort governing sex.
Most of our species finds it comforting to be able to identify our individual selves within the context of our particular tribe. In social terms, that seems to translate as a need to know who at least one of our parents was - for the public record, if nothing else. By tracking the parentage of its members, a society doesn't just ensure that everybody has a name of some sort. Once you've got some basics laid out, broaden your scope a bit. That means every single member of his society uses it every day to some degree.