User blog comment:Wrath022/Chapter 516: The Truth About Enchantment, Review/@comment-4507125-20161231163540/@comment-7418318-20170101092351

But the cause might well be the same, just a different individual reaction to it.

Just like different people react differently to certain medication or plants. For example most people find lavender calming, but my sister get's nervous and twitchy from it.

It could be something similar with Irene. Most DS that have their minds screwed over by the transformation become agressive to the point of losing control, but due to individual differences Irene instead lost her empathy and became sadistic. Of course that could also be a result of her years of imprisonment and torture or a combination of those two factors.

Whatever the cause or causes, it's pretty clear that she is not the person she used to be prior to the transformation setting in.