Who is Millie from Blood of the Fold and what is their importance?

Millie takes care of the housekeeping at the Palace of the Prophets. Before her death, Annalina entrusted her prelate ring to Millie and told her what to do with to set up the spell that chose Verna as the next prelate. Millie slips Verna a dacra while cleaning out her cell after Verna has been found guilty of being a Sister of the Dark.