Right, Dean does make mistakes as well, and I think that understanding them is another key to understanding Sam and the reasons he makes some of his decisions. In conversations I've had in the past, that get dismissed a lot because some fans think that Dean never made any mistakes. Dean IS righteous, and he's never EVER wanted to hurt Sam, but that doesn't mean that he wasn't unintentionally to demanding sometimes, telling Sam what he should do or be. Holding too tightly, really. But the point is, both of those boys have done and said some things that hurt one another, but it's just part of life. In the end, it's about forgiveness and understanding. (And, well, love - but it's always about love.)