HowToKillAVampire
Sam Winchester just summoned the devil. Not for nefarious reasons- quite the opposite. He needed Lucifer to help him close the Gates before all of Heaven, Hell, and Purgatory broke loose and started a war that wiped out humanity for good. But before they could do that, they needed to outrun their older brothers, who were hell bent on starting the apocalypse to settle the score for good.
And it just so happened that Sam already knew the devil. Not as Lucifer, not as the angel who was cast into the pit. But as a young boy named Luke who came into his life when he most needed a friend.
OR
Bobby and Crowley convince God to let Lucifer meet Sam Winchester on his seventh birthday to see if their friendship could change the course of the apocalypse.