Every time I am playing Act 3 I am always struck by confusion when I come across one of those giant demons chained up in the Towers of Sin. A maroon of questions pass through my head each time I see one:
- Why are they being tortured?
- Why are all of them being tortured? Did they all do something wrong?
- Why is Azmodan torturing his biggest demons when they could be used against the player?
- Exactly how did the smaller demons manage to overcome these much bigger ones?
- And many more...
At this point I didn't even know what they were called (or if they even had a name), so I took the the story section on the official forum and created a thread there. Before I post my findings, let us first take a look at these demons just in case you can't recall them:
Over time I received many responses to my original thread and even got a name for these demons; apparently they are called "Flayed Ones". According to lore gathered by the players, these demons are unwilling servants of Azmodan that are tortured by the smaller demons who also take their flesh (flay them alive, hence their name) as building materials for the towers themselves. The reason I never got hold of this information myself is that it is only revealed when walking past these demons by Eirena; a Follower I don't tend to use.
Update: It appears that the Scoundrel also has some in-game dialog about these creatures, but I have yet to see them myself. Thanks to Wide-Eyed_Penguin and CS_83 for pointing this out. I also have a screenshot of the in-game dialog provided by Eirena thanks to OptimusPrmDS from Reddit.
Of course there is one in-game lore I did encounter, and that is when Cydaea comes down and tells you that she feasts on their agony. While this does make some sense since she is a demon after all, it falls short in terms of lore since she is the embodiment of lust. Her concept art suggests that she was originally going to be the Maiden of Pain instead, so this dialog was probably implemented at that point and left there.
Another purpose for these demons was theorized by forum poster Immaterial, who said that the Sin Hearts are actually taken from these monsters.
"i think what is going on is that these massive beings are tortured perpetually, and then when one of them has experienced enough agony or malice or what-have-you, the heart is torn from it and placed as a magical beacon that broadcasts all of the pain, suffering, anger, hatred, and malice that being felt as it was tortured."
This could very well be true since the only dead "Flayed Ones" you see are found right before you destroy the Sin Hearts, and there are even 2 directly next to the Sin Heart with their chests thorn open.
If this is indeed true, then these demons support the Towers of Sin both physically (by having their skin used as building material) and emotionally (by feeding Cydaea while they live and the tower itself after they die).
Another thing I noticed is that in the Core of Arreat, right before entering Azmodan's room, you see 2 Flayed Ones melted into the walls themselves. Not sure what this means exactly but it could also indicate that they use their dead bodies as building material too.
People that played Diablo 1 may remember that there was also a demon called "Flayed One" in this game, but I doubt they actually have anything to do with each other. They are very un-similar in terms of looks and their name is probably just a coincidence since Azmodan's minions never appeared in the previous games. There was also a unique chest armor in Diablo 2 called Skin of the Flayed One, but like monster from Diablo 1 I doubt this is related.
So in the end we may never know why exactly Azmodan doesn't use these creatures against the player, but at least we satisfied our curiosity a bit. Who knows, maybe we will get to fight them in an upcoming expansion!