Everything you mention is true, but the emotional part isn’t that far off. Lots of characters like Demis would not be “clever” or “perfect” especially when their emotions get amplified by the fact they’re psychotic. It just fronts as even more childish and emotional unstable.
Now that I think about it, I believe the point is that the story shows he’s clever enough to hide the fact that he’s a serial killer and manipulate a man to stay with him at his mansion (although that man is a dumbass too), but he’s incapable of understanding his own feelings. I think I’m comparing him to Hannibal Lecter, who, although he’s a psychopath, is a man capable of understanding his own feelings and those of others....
Dr. Demis might be the stupidest doctor/serial killer I have ever read... he's emotional, brutish, childish af with a huge victim mentality lmao like, I'm kinda resenting the author because they clearly can't write a clever character vehsjsks