Side

Side
 

My sentence as usual:

-The author of the story wanted to show the dark side __ human beings.

Are to and of both correct? If yes, what's the subtle difference between the two?

Both can be used, in this context. There isn't any difference that I can tell. I will say that most folks in the US would choose to say 'of' instead of 'to'.

Excellent answer. Thank you.