This is a list of when NPC flags are set.
Flag  NPC                Condition
5     Lord British(5)    after you ask about the moon orb
7     Lord British       after you pass the Compendium quiz and he tells you
                         the state of Britannia
      Nystul             when you speak to him the first time; if set he will
                         not speak to you until you show book to Mariah?
6     Ariana(13)         when she gives you the Rune of Compassion
