I have noticed Jensen Ackles do this with other roles that he portrayed, for example, TV-Shows like Dark Angel as Alec McDowell, Smallville as Jason Teague and in the movies like Devour as Jake Gray and My Bloody Valentine 3D as Tom Hanniger. Jensen has the range and nuance to play a puzzling, many-sided character with seeming ease, giving us an opportunity to share in Dean’s agony, rage and happiness.
Dean Winchester is a flawed hero and that’s what makes him ideal. He can be overbearing, bossy, stubborn and close-minded, but he can also be brave, intensely protective, unconditionally compassionate, and extremely loyal. Dean Winchester can be amazingly altruistic and incredibly narcissistic, or sometimes in the same breath, for example, in the season 2 episode 22 “All Hell Breaks Loose, Part II. No one can narrate to a character without imperfection and Dean has them a plenty and willingly admits it. He doesn't endeavor for perfection. He doesn't even think of himself as a hero. He does what needs to be done