I have captured several human necromancers, zombies, a troll, an Amphibian Man Fisherman necromancer, and a giantess.
I've chained the Amphibian Man Fisherman necromancer, and sometimes I have noticed a blue exclamation mark flashing on him, implying that he is in a melancholy mood. I've also noticed a brown exclamation mark flashing, but I'm not sure what that is. These moods go away after a few minutes, although I'm not sure if one day the mood will become permanent.
Do all enemy prisoners experience moods? I haven't noticed it on any of the human necromancers or the giantess yet. Can they go insane? Do I need to do anything to keep them happy or in a non-insane mood? Can they die from mood?
EDIT: Now the blue exclamation mark keeps flashing and won't go away. I think it's melancholy mood, but there isn't anything on the wiki on non-dwarven prisoner moods.
EDIT2:
Well, there's not much info on this, so I'll state my observations so far:
Amphibian Man Fisherman necromancer has a dark blue exclamation mark flashing permanently, implying melancholy mood.
A Human necromancer has flashed a brown exclamation mark, which eventually turned into a bright blue exclamation mark after some time, implying the human necro is now mad. His clothes are shrewn all over the floor also, which further reinforces this suspicion.
Elven merchants and guards can go insane in captivity; I've seen berserk and melancholy moods, but the melancholy status won't show up in the units screen
u
, except for berserk mood.
So, three things that remain a mystery are:
What is the brown exclamation mark that flashes that foreshadows an oncoming insanity?
Is there any way to prevent insanity while being captive? I can give them nice furniture and food, but I can't tell if it works or if they have really high stress tolerance.
Do all (learn/intelligent?) captive beings eventually go insane? ie, Trolls, slugmen?