So what changes are enforced on your characters? Who is the enforcer? Why are they doing what they are? Could anything/anyone make them change their stance and act more honourably?
Weather, and the darker evenings coming in, can, of course play a vital role in a character's attitude but also in their overall health levels. Sunshine lamps are often used to combat/help in the fight against depression. So which of your fictional characters would need something like that?
And what changes are enforced on your fictional world? Is there such a thing as climate change? What is the normal climate? How do people live, based on the seasons, which are unchanging?