Following Dean’s mother death hope was all that Dean had. This hope keep whacking and whacking and Dean bargained and fought and gave up and fought again and grieved. Hope hung on even when Sam died at Cold Oat, plunged to hell at Stull Cemetery, and withered after the Trials.
When Dean’s hope faced Sammy’s declaration he had a brother no more hope just scorched, twisted into a cinder at Dean’s feet. Something new whacked Dean up the side of the head for the first time. It was despair. The new whacker struck hard, and deep so Dean took up The Mark made out of hell fire. Now hope was forced to find a new head because that was all hope had and whacked Sam up the side of his head instead.
Something happened to hope at that derelict Mexican Canitina when Dean saw the photos at Sam’s feet. Hope wasn’t even born back when little Dean had no need of hope, nor cared what it was. That was before he burning ceiling. Now the old hope was transformed into something more, as the scythe cut into Death’s heart and Sam lived. What had this new hope been transformed into whacking Dean on the side of