Former Guns N' Roses manager Alan Niven once told me that rock 'n' roll is created because people are subconsciously trying to form the perfect family that they didn't experience as children.
As transparent as that may seem, it's an easy concept to grasp. Heavy metal lyrics celebrate the underdog and the unknown, sticking a big middle finger to society, and marionetting the masses, demanding that we act, feel and look a certain way. The most amazing guitarists, drummers and bass players in heavy metal admit to spending most of their childhood alone, honing those musical skills.
The darkness of heavy metal and rock is one that often pulls people into the light. Finally understanding that journey is usually the revelation that prompts an influential musician to write down their story that they fought so hard to create. And while the exploration of that journey usually leads down some dark paths, as they say, "The darkest hour is just before the dawn."