There is one place where this doesn't hold true.

A narcissist (sociopath) and their gas-lit victim.

The narcissist will appear completely in control
While the victim will appear extremely emotional, unsure of anything and as jumpy as a long tailed cat in a room full of rocking chairs.

The victim has been living in a world where they are told up is down and left is right. They are being driven insane.

The way to really tell if someone is a narcissist is to find several of their acquaintances and try to corroborate stories. The narcissist tells each one a different lie.