Today I was fighting the Ettins, and I realized that my first battle with them gave me over 4000 gold! :D The second battle with them, however, only gave me about 500 gold. :l Still okay, but how does it get from 4000 all the way to 500? The first battle was even easier than the second! I fought a third battle, to finish the quest, and I was awarded about 150 gold. >_< How does that happen? In that battle I even lost a companion! It was that hard! Please explain this to me.
From fight to fight against the same enemies, how easy or hard each batte was has nothing to do with it as far as I've seen. It seems each creature gets assigned a random treasure chest prize (an item or gold amount within a particular range, usually based on their level). The more enemies involved in a particular fight, the more chests you get, so the more gold you'll get in the long run - but there are always extreme cases either way. Some times you could get really lucky and all the chests scored near the top of their gold range, other times could be unlucky and their chests are all at the lower end.