Why do we fear and adore snakes?

Snakes eat rodents and thereby prevent them from spreading disease and in addition they eat seeds and thereby replant the forest. But, even in their role in the natural order of things, snakes are perceived to be cold and calculated killers. 

We view psychopaths in the same way.

As Robert Hare famously referred to them in his book ‘’Snakes in suites’’  Hare was focused on the so-called successful psychopaths not the serial killers and common criminals.

So much like snakes they seem to have a roll in the natural order of things, but what is that roll and how they influence in our society?