The first to go was Cas. Dean had wanted to insist that they leave him at the motel, that Cas wasn't strong enough, but he knew they needed Cas. And he knew Cas would not allow them to leave him behind, even in his human state.
The blow was low and fast, landing right below his heart. Dean yelled out, but Cas didn't have time to react. He looked down at the blade, then up at the angel who put it there, and then fell to his knees. The angel disappeared in a flutter of wings.
Sam and Dean cried out, simultaneously killing the angels in front of them. Cas was on his back, struggling to breath. Dean dropped to his knees by Cas' head, pushing the hair out of his eyes and mumbling soothing nonsense to him. Sam hit the ground and pressed his hands over the wound, trying to control the bleeding. Cas coughed, and tried to form a sentence, but Dean shushed him, stroking his hair.
"It's okay, it's okay. I'm here. Shhhh. I'm here." Dean murmured, tears streaking his face.
"Dean….. I…. didn… I didn't…. change…. You… told me…. not to…. and I didn't…" Dean choked out a laugh.
"I know you didn't Cas. But you can't go Cas. You said you'd wait. You said…"
"Dean… it's okay…. I will… always… wait… for you." Cas clenched Dean's shirt tightly as he coughed. Dean pressed his forehead to Cas', clutching at his trench coat.
"It'll be okay Cas. You're gonna be okay... I need you to be okay."
Cas smiled slightly. "I am... Dean..."
Dean choked back a sob as Cas' grip on his shirt slackened and his hands slipped away. Dean gazed at the ex-angel, who could have been sleeping, except angels don't sleep.
Sam and Dean went together. The angel appeared again, shortly after Cas died, and the boys fought harder than they ever had. Only when the angel was laid out on the floor in a mess of wings did they stop to assess each other. They surveyed the blood and body language and they knew they were going together.
As Dean took a step towards Sam, he collapsed onto his hands and knees. Sam started towards him, with a choked "DEAN," but as he reached Dean's side he too crumpled to the ground. Dean rolled onto his back, grasping blindly for Cas' hand, and then Sam's.
They lay silently, regulating their breathing and contemplating the fact that they weren't coming back from this hunt.
"Dean…" Sam suddenly spoke up. "I…."
"No Sam… No more…. chick flick moments….. It…. was girly… enough when… Cas died." Dean cut him off, flinching as he coughed.
Sam chuckled and then winced as the laughing made him cough more. "No, seriously… Dean… I just…. I wanted…. to say that…. you're a jerk…"
"And… you're… a bitch…. Sammy…." Dean clutched Sam's hand tighter, not wanting to be alone. Sam smiled slightly and returned the pressure.
"Together." Sam whispered as Dean's grip weakened. Then Sam closed his eyes and exhaled slowly, sinking into the all-consuming black.
Bobby found them, and buried them in that order; Sam, Dean, Cas. He parked the Impala at their heads, as an ever present memorial. This was Team Free Will at the end; one ex-blood junkie, one dropout with six bucks to his name and an ex-angel of the lord.