Bluther is actually from what we see missing half of his soul (or a decent portion of it) the curse of undeath isn’t as big of an excuse for forsaken, DKs legit have a reason why they fall to doing something abhorrent because of the need to cause suffering lest they feel unimaginable pain that Arthas (and apparently Bolvar) put on his knights. Forsaken like DKs have their souls imperfectly bound to their bodies but they’re not beyond feeling emotions entirely as you imply allot of the times and most who are raised by the Val’kyr are raised in such a way that leaves them confused or in a berserker state, as we see in the starting zone. But they have been also shown to calm down, they’ve also been shown to still feel emotions like the desolate council members in before the storm.