Oh, you mean the change the chance of personalities based on difficulty levels.
But this would assume some difficulties are easier to beat than others and I have doubts about that.
Maniacal uses curses a lot, but keeps more summons in garrison so their attacking forces are weaker. Ruthless uses less curses than maniacal but might send massive forces to attack. Chaotic is average but diplomacy doesn't work on them at all which makes them bad. Peaceful is friendly but ally with the others and attack you for that.
But this would assume some difficulties are easier to beat than others and I have doubts about that.
Maniacal uses curses a lot, but keeps more summons in garrison so their attacking forces are weaker. Ruthless uses less curses than maniacal but might send massive forces to attack. Chaotic is average but diplomacy doesn't work on them at all which makes them bad. Peaceful is friendly but ally with the others and attack you for that.