bobad surely put his finger on it when he wrote "I believe one of characteristics that define a sociopath is the inability to feel empathy toward others."

That's how they are built. For those of us lucky enough not to be sociopaths we are wired so that it's virtually impossible not to feel some kind of empathy towards people who are suffering, when we are actually brought up against it.

That might not mean we may not feel they'd be better dead, or even feel bound to ensure that happens, but that's something different.

Anybody who ever finds themselves actually taking pleasure in seeing someone suffering needs to recognise that, for that time anyway, they are cut off from humanity, and are a danger to themselves and others.