Pick Myself Up Off The Ground (слэш)

When hellhounds came for his brother, Sam was overwhelmed by grief and guilt, and willing to do anything to bring Dean back. Then a man who looks just like him shows up from the future with a story of angels and Armageddon.
This other Sam is dealing with his own guilt and loss, but he has a plan to stop the apocalypse before it begins and to rescue Dean. Now, the two of them must work together - two Sams to bring back one Dean.