You may find, too, that we often make a distinction between NPCs and Townies. I believe (and may be swiftly corrected ) that NPCs are the characters that have a role to play other than innocent bystander. They are the maids, the gardeners, the firemen, policemen, burglars, mailmen, bartenders, etc. I think that one of the Legacy Challenge rules was to marry NPCs, not Townies (like Amin Sims and Sandy Bruty.) I was very fuzzy about this rule when I first got the game and tried the Challenge. Actually, I'm still fuzzy.
Whereas I can't be bothered to care what the distinction is, though I've gotten corrected more than once.