They buried Castiel under an oak tree in Pontiac, Illinois, with a full moon shining overhead. Dean had insisted on digging the grave himself, while Sam looked on quietly. He watched his older brother dig for hours, until the blisters on his bare hands split and stained the handle of the shovel red. He watched him pull Cas's lifeless body from the backseat of the Impala, carefully cradling the smaller man in his arms as if he were merely wounded, not broken and twisted and dead. He choked back his own tears, standing stoic and straight, as Dean wrapped the angel in a gauzy white sheet and lowered him into the ground.
Only when Dean collapsed on his knees in the mud, frightening and fierce sobs ripping from his chest, did Sam turn his eyes away. He knew, although the two had never told him, that the love between them had been different, so vastly different, than the admiration he had for their friend. Cas had once called it a "more profound bond". That is why, when Dean had told him to take the Impala to the hotel room, that he would find his own way back, Sam listened. Pausing only to lay a hand on his brother's shoulder, he climbed into the driver's seat and turned toward their temporary home. He would never forgive himself.
Dean didn't stand up until the roar of the engine had long since faded into the night, replaced by the sound of the wind rustling the tall grass. His face was streaked with dirt and tears, and a few more hiccuping cries escaped his mouth before he could compose himself enough to talk.
"Cas..." He started, hating the way his voice faltered around the name. "I know I never said it in so many words, but I think you knew... how I felt about you, I mean. Dammit, man, I wasn't ready for you to die." He paused to scrub a muddy hand over his face and wrap his leather jacket tighter around him before he continued. "I want you to know that I loved you. I love you, still, even though you're-" He couldn't bring himself to say gone. Never gone, never far away from him. That had been Cas's promise, whispered in his ear one night. I will never be so far away that I don't hear you when you call. "I'm so sorry I couldn't save you, after all the times you rescued my sorry ass, pulled me out of hell." The handprint, now an almost invisible scar on his arm, throbbed at the words. Had it really been that long? For a moment, his resolve faltered as nostalgia took over, but he fought it back. He needed to do this. For Cas. "You made me so many promises, so I'm going to make you one now -you're never going to be alone. I'm coming home."
From his bed, Sam almost swore he could hear a gunshot.