This is a quote which has stuck in my mind over the years. I had a very good friend at university many years ago who told me it at the time, but I can't remember who said it, and neither can he the last time I asked him. Anyway, I believe there to be some truth in the saying - not least because I have a Metal past, so yes I would say that wouldn't I? But aside from that, my thinking is that Metal is fundamentally about rebellion, and obviously most teenagers go through a rebellious phase. Not every teenager will be into Metal though, there are many ways to rebel. So what is special about Metal? I think it expresses both anger and depression very well, common teenager symptoms. I've heard it said that depression is anger turned inwards. I was by turns both angry and depressed as a teenager. To me, Metal served as an emotional release. I even found it relaxing to listen to. I used to listen to Motorhead's 'No Sleep At All' live album in bed as I was going off to sleep (not strictly Metal but you get the idea). Sorry I'm starting to ramble here, but I suppose my main point is that Metal is for people who are pissed off with the world, or with their world, and I think people who feel that way are often good people in my experience. If you've been through some tough times and come out the other side then you've probably learnt some lessons in life and gained some insight and wisdom, and if you've been a Metaller then you've probably also got some fire in your belly, and I like those kind of people.
Never trust someone to be anyone other than he is. If one has a past mired in emotional turmoil, that led him to act rebelliously towards those who were on his side, then as circumstances happened to get better, through no credit to himself, he abandoned his rebellious side with no rational reason, then should circumstances become difficult for such a person again, trust him to once again turn against whomever and whatever he isn't pleased with at the moment.