Demeanors?

[General Hawkwing]

The different demeanors have an influence on your population's happiness. They help determine what actions/occurrences will change population happiness. I'm not sure as to the weight they are given in determining happiness.
The AI demeanor will influence the AI's initial reaction to you and how they interact with you after that. It also determines (somewhat) their willingness to give tribute/gifts and to surrender or die.

[Jubala]

So what demeanor has what effect? I usually go for honorable.