A sociopath has a high social IQ in saying this what I mean that sociopaths understand how people react, one could say sociopaths understand body language down to a fine art. So the sociopath charm a sociopath can express is one that is not easily escaped yet alone noticed. Just like it is contagious when someone smiles the reaction we generally have is to smile as well, even though you might not know the reason for the other person smiling. All in all we react based upon the emotions of another, we know that when a person covers their mouth, ears or eyes with their hands that this is the classic “Hear No Evil” “Speak No Evil” “Say No Evil” and I know I am being general here but bare with me for a moment.
A sociopath knows that if they express themselves to you in certain ways that they will get the desired reactions from you that they seek.
Just like a pick up artist tells you want you want to hear, a sociopath tells you want you want to hear, the same as a salesman sells you something a sociopath sells you their dream.