[Sam and Dean] both have their stories. But I always say that it’s about them coming together, because the story is really not about one or the other; it’s about the bond between them. It’s about this connection of the two of them. The two of them being one unit is for us really what the story is about.
And people online, they get furious – alternately furious and upset – or they throw their arms up because they think we’re focusing on one brother or the other, and some people are Sam fans, and some people are Dean fans. And in my mind, anyway, you know, they’re both on completely equal footing because the story is about the two of them being intertwined.
Eric Kripke interview with the Chicago Tribune in 2009. Still 100% true in 2016. (X)