I have no idea where this story came from and when you go listen to the song,(either version) you'll wonder too! "Starry Eyed" (dubstep) by Ellie Goulding. PS: This was written well before this season (S7)

Sam sat on the toilet in the bathroom, slapping his forearm till his skin turned red and the vein showed, he tightened the thick rubber band around his arm with his teeth. He then reached across himself to pick up the needle off the sink; he pushed a little on the end of it and watched the drug slide down the needle. As he was about to put it to his skin Dean came pounding on the door,

"Sam come on I haven't got all night!"
"Alright!" Sam said through clenched teeth, bending over to pick up the needle he'd dropped on the floor.

Blowing off the tip of it he quickly pushed it into his skin, into his veins. He felt the warmth travel up his arm and then disappear as it dispersed throughout his body, he sat there for a minute or two before he got up and "flushed" the toilet tossing the needle in there too. He turned on the water in the sink and ran his hand under the cool water, then ran that hand down his face.

He felt hot all over, and the room began to tilt but Sam paid it no mind, he looked at himself in the mirror and smiled at reflection out of sheer stupidity.
He knew he was done for…
He gripped the sink tighter as he felt his knees weaken beneath him, he swayed back and forth and his head clashed with the mirror and Sam could already hear Dean's worried footsteps getting closer to the door.

Sam slowly laid down on the facing the ceiling, the rushing of the water coming from the faucet got louder, Dean's pounding on the door seemed to vibrate the whole bathroom, he screams and demands to open the door meshed with the already ringing inside his head.

Outside, Dean's demands had to turned desperate cries and kicks at the door but he'd had no luck. So he began to scream Cas' name till he was hoarse, it's when Dean had finally thought about it, the angel was gone, the man who Sam had given his all to, the very same who Dean would've given his all for.
"Castiel is no more…" Dean said stopping his kicks on the door, he reached into this back pocket and took out his gun, his slide down to the floor with his back to the door. 'And that's my fault…'

Still waiting for death to come and whisk him away Sam heard Dean's barely recognizable or audible over the still rushing water, "I get it Sammy, I do. You miss him, and I—" he could hear his brother choking on his tears,"I do to Sammy. Truth is… I loved him so much,"

Sam hear the click of the gun outside the door, had he not been so disoriented he would've told him to stop and reconsider what he was doing, but right then and there Sam didn't care, "…I didn't realize it would come to this, I never thought you'd find out and I'm sorry that you did and if this...constant ache in my chest is even half of what you're feeling in there Sammy, then I understand.
I really do, and I wish I could save you from your pain and save me from the guilt that's eating away at me, but I can't. So Sammy I guess that what I getting at is that, when we- - when get to where we're going if we meet up with him, do you think that maybe we could put this behind us?"

Sam drew in a breath to answer his brother but the words never came because his lungs had just then given out, Dean still outside the door crying and unknowing, didn't hear a response so he took it as an answered and pulled the trigger.