India celebrates Dasherra or Vijayadashmi today, a day that marks the victory of Good over Evil. We go back to our mythology epic Ramayana. Lord Ram, representing the good, kills Ravan, representing the Evil.
Good and Evil can get quite intriguing when you realise things are not as we see, but as shown. Once we know the circumstances, it can be challenging to classify events and people into good and evil. It can be a deeply subjective matter.
An area which great scholars, religions and philosophers have been trying to elaborate, deliberate and express for centuries. An excerpt from Sapiens by Yuval Noah Harari

Only when there are options to choose from and the choices differ, the debate on which one is good and which one is evil (or not so good) starts. In a monolithic world, all are either good, or all is evil. Really?
So is the fundamental question then, what is Good and what is Evil? Or why good is good and evil is evil
Good is good because of Evil
Evil is Evil because its no good
Two sides of the same coin
Or separated by a blurring line on a plane
Both Good and Evil when co-exist
Clear to use one for the other to explain