Humans can be totally evil at some point in life. At times the power fueling the evilness can be the extreme authority, and for some other times it can be just a personal deeply rooted fear.
The fear that slowly and cruelly transform into a power hungry beast without thinking anything as it lashes out.
Duncan wasn't just trying to make Regina or rather Rachel D'Azure a culprit who was being disrespectful to the king, he was trying to make her a persona who was prideful enough to decline the decision taken by the court of royals and aristocrats.
"Pft. You were indeed foolish enough to make a promise with me and then go ahead and break it. How stupid of you." Duncan thought to himself as he declared what actions he was going to take in his further steps.
The count was anxious and his anxiety was enough seen on the quivering ends of his lips as he tried to stay as calm as possible.