From the Accorded Neutral Ground thread, here are some questions we can ask:
1. Which known characters in myth and legend are known to be mute, or nearly mute?
2. Which are difficult to amuse?
3. Which are ageless, or close to it? (Mac is still described as looking between 30 and 50 fifteen years after he's first introduced). (Is there a painting of Mac slowly aging in the pub's basement?)
4. Which are Celtic or Scottish?
One of my thoughts was the Green Knight, a quiet, mysterious entity who's named different things in different stories, but is usually depicted in some kind of judgment role.