In Season 10 episode 3 ‘Soul Survivor ‘
CASTIEL: Sam, he’s not your brother. At least, not now. You have to be prepared for—
SAM: Killing my brother.
Dean asks Sam if he is prepared to do what needs to be done, if the cure doesn’t work.
DEAN: Who cares what you meant?! That line that we thought was so clear between us and the things that we hunted, ain’t so clear is it? Wow. You might actually be worse than me! I mean, you took a guy at his lowest, used him, and it cost him his life and his soul. Nice work.
[Sam plunges the next needle into Dean’s neck, and he screams in pain. Sam tosses the syringe onto the table, leaning over it, pain and regret on his face.]
DEAN: Let me ask you this, Sammy: If this doesn’t work, we both know what you got to do to me, right? You got the stomach for that, Sam?!
At the end of the cat and mouse chase in the bunker when Dean goads Sam to kill him, Sam backs off, only to have Cas catch Dean from behind. Would Sam have gone through with it if Cas hadn’t have gone back to the bunker to help a friend?
Season 10 episode 9 ‘The Things we carried ‘
DEAN: Cas, I need you to promise me something.
CASTIEL: Of course.
DEAN: If I do go dark side, you got to take me out.
CASTIEL: What do you mean?
DEAN: Knife me. Smite me. Throw me into the freakin’ sun, whatever. And don’t let Sam get in the way, because he’ll try. I can’t go down that road again, man. I can’t be that thing again.
So quite a way back Dean new that he would have to be put down at some point. He knew he was a monster at this point, and the demoness in Dean knew what Dean did for a living. Dean’s exact words to Cas were that – And don’t let Sam get in the way, because he’ll try. So does Dean think Sam might or might not be able to take him out, if the crunch came? My thought then comes into this equation if Sam or Cas couldn’t do it the terrible god awful thing could Dean himself actually go through with it, and take his own life? This is where I’ve been thinking this season might go. This has been at the back of my mind bubbling away for an what seems like an age already. But if Dean is mortal that could never happen in their real world? He would just be bought back to life? So what’s the point in even taking the story there? It just tickled me that it was bought up more than once on the show, and that it might even still happen….
A human has to put a pet down if the vet thinks the animal cannot survive. This is being brutal here, but facing facts we know Sam couldn’t cope with that awful task, could even Cas? Cas is getting pretty close to Dean these days, and we sense in some cases just as close as Sam is. Could Cas actually pull that trigger, or stab that Knife in and go for it? Cas already sees Dean as a monster, and in his eyes he has to end that monsters existence. But knowing its someone he knows well, could he stomach that awful act just as much as Sam has to bare? Is suicide the only option that is open to Dean right now? Or is there another different direction this could totally go?