People who call other people »Dearie« are nowadays mostly characters in novels, where they
- might be intoxicated, groggily grabbing your arm
- might be nurses (»This won't hurt a bit!«)
- or matrons of orphanages that you the hero/ine quickly run away from so the plot can get underway
- or proprietors of dusty curiosity shops
Only in rare cases, in the case of a character like KD's Frank Leigh Dearie, is Dearie a proper name. We're watching Frank to see just what kind of a character he might be.