Relapse. Remission. Cure. The language of disease has been a hallmark of Supernatural season ten. It's been discussed overtly and in metaphor. It has been explored through various means and methods. In “The Executioner's Song,” we see the theme of disease play out, allowing us to see how each character's story fits together, summing up the storyline surrounding the Mark of Cain, Cain, and the Winchesters themselves. Cain tells Castiel, “Yes. And soon it will be a genocide. My children, my whole poisoned issue. Lot of them out there right now -- killers, fighters, thieves. Some more peaceful than others, but they still carry it -- the disease.” It is this disease that becomes a focal point of the episode, revealing the truth about it and the fight the Winchesters will have against it.
In the beginning of the episode, we see Cain come for the prison inmate, Tommy. He is on death row, marked for execution. Tommy killed six people---at least according to the state records. By Cain's count, it's nine. He tells Tommy, “I know you're a killer---just like me.”
This is the first example of disease being discussed in the episode. Cain, as the Father of Murder, is patient zero. He's the first human to ever take another's life, and he has been killing ever since as a demon. It was part of the deal he made with Lucifer---all to prevent his brother from becoming the demonic monster. He has killed countless, culled thousands, and committed unspeakable atrocities as the original Knight of Hell.
When we first meet him on Supernatural, however, Cain has retired. He threw the First Blade away into the deepest trench on earth, gave up murder, and decided to keep to himself as a hermit living away from the world. It allowed him to explore quieter hobbies---such as bee keeping. It allowed him to quell the murderous noise in his ears. Cain was able to step away from Hell, step away from killing, and find some form of peace.
After Crowley and Dean go to him in order to acquire the First Blade, they draw unwanted attention onto the retired Father of Murder. He is confronted with demons led by his former protege Abaddon---and they want nothing more than to disturb his peace. This peace was brought on by Cain's love for Colette, a woman that Abaddon possessed and Cain killed. She was to be his last kill---until now. In the wake of this, we can see that Cain has thrown aside his vows, that he's picked up killing, and that he's struggling against the very same thing Dean has been throughout season ten: the Mark of Cain.
When confronted by Castiel, Cain tells the angel, “What can I say? I got the taste back.” He's not the only one. The Mark thirsts for murder, too. It is pushing Cain to return to his old ways, but he's chosen to do so on his own terms. He explains, “If the Mark wants blood, I'll give it mine.” It's why he's culling entire families. They are tainted with his own sins, with his own curse, and he knows that among them there are killers like Tommy. Rather than allow them to inflict that kind of horror on others, Cain will do what he sees fit when it comes to an incurable disease: he'll cleanse the rotten parts and pray there's something left to be salvaged.
Already on the search for Cain, Sam and Dean follow him to the prison and see him on the footage. Dean knows, even with the dark shadowy image making it hard to see, that it's Cain. The Mark on his arm hums in recognition of its originator, and he knows that they're close to finding out if Cain can answer their questions. He's already succumbed totally to this disease once, and he has no wish to do so again. Cain, at this point, might be their last hope in learning a cure.
It isn't until they learn that Cain has decided to go after Tommy's son that they realize he's gone too far. Cain has totally fallen back into the disease---he's no longer salvageable. Tommy's son is only twelve years old---an innocent. He may or may not kill someone later on. He may or may not be tainted with the same disease of the killer. Rather than taking that chance, seeing if the little boy, Austin, can manage to be better than he was, Cain decides to remove him. He tells Dean, “He could go either way. I prefer to be thorough.”
While we shudder at Cain's reasoning, we can't help but see some logic in it. He has a point that the world would be better with a few less murderers. He's right that most of the killers in the population are descendants---either literally or figuratively---and one way for the world to see this fixed is to kill the killers before the cycle begets more killers. He's seeing these men and women---and children---as an epidemic of his individual disease. As patient zero, he's the most afflicted, he's the one that has suffered the most. As patient zero, he's aware of how dark and gruesome this disease will get if unchecked.
But he's not the only one.
Dean, too, is afflicted with the same disease. He, too, bears the Mark. Its hum is in his ears. Its pull is on his mind. Throughout the season, since Demon Dean was cured by the purified human blood, we've seen the Mark of Cain dictate to Dean what it wanted in subtle ways. It spoke through its unending pull on Dean, causing him to grasp at its raised flesh on his arm at various intervals. It pushed him to do things he didn't wish to do---such as shoot the shape-shifter Olivia multiple times, slaughter an entire house full of men, and lose his control when questioning Metatron. It feeds on his aggression, his struggles with his self worth, and with the darkness that he needs in order to be a good hunter. We've seen it speak to Dean in metaphor, too. It spoke through the vampire, Starr, telling him brazenly that, “all of you will become all of us” and that to resist its command to kill is to end up dead. The Mark has been biding its time, waiting to break through to Dean in order to wrestle control from him.
Now, the Mark has its greatest mouth piece ever: Cain himself.
Sam, Dean, Castiel---and Crowley---all set a trap for Cain. They know he's coming for Austin, and so they lie in wait and allow him to show up. They'll confront him head on, rather than chase after him. They know what he's after, and they know what they have to do. They'll need him to get into the barn and enter a giant Devil's Trap. It's a bothersome thing to something like Cain, but it'll hold him if for a moment. With the little boy in the center of it, they give him what he wants. He stabs the child, only to watch him turn into a poof of purple smoke. Cain seems rather unsurprised by this illusion, almost peeved that they'd think to try something so juvenile on him.
But in reality, Cain knows that this was just the ruse to get at what they really trapped him for: Dean.
Dean tells them that he's going to have to go this alone. As the person with the disease, this is no different than a patient having to go into surgery, endure a medical test, or take something like chemo on physically alone. No one can do this for Dean. If he is to face the disease that has permeated his life, he will have to do so head on and without distraction. This level of honesty with not only Castiel and Crowley---but most of all his brother Sam---conveys that Dean knows how important this moment is to both of them. This could tip the scales towards Dean relapsing into the demonic creature he was after Metatron killed him. It's a scary thought, that this confrontation---this moment he faces his disease personified---might be the last thing he does as himself.
As honest as he was in admitting that he do this alone---and that they must kill whatever comes out of that room if he should succumb---it is his sheer honesty solely with Sam that lays bare just how frightened Dean is of his disease. This may be one of Dean's most vulnerable moments, and he simply says, “I'm scared, Sam.” It's key that he voice this fear now and only to his brother. He may not have Sam's physical presence with him in that room, but he needs Sam to hear this---and he needs to say it so he can face both the disease and his fears surrounding it. It's his one chance at emerging intact on the other side.
As Dean steps into that room, Cain is waiting, caged for now. He tells Dean, “This is the part where you tell me it's not too late. I can lay down arms. Abandon my mission. We don't have to fight.” At this stage, Cain morphs into the Mark of Cain personified. He has fully fallen to the disease, and therefore he becomes its most powerful mouth piece. From the moment Dean steps into that Devil's Trap with him, to the moment he bows his head to receive the killing blow, he is voicing everything the Mark has been hinting at for months.
Dean knows that he must kill Cain. After all, Cain is killing scores of people. He's killing murderers and innocents, men and women---and if left to his own devices, children. He's embracing the blood-lust, taking back the taste for it, and fully feeding its need for human blood. There's no question in his mind that Cain needs to be stopped. Dean's the one that bears the same Mark that makes it possible to use the First Blade. He's the only one that can do this.
And do it he must.
But it's not for those reasons. It's never been for those reasons.
As Cain starts to push back, overpowering Dean, he starts to spell out the very things Dean has needed to hear. He's been playing with a partial deck, only knowing so much about what his disease wants from him. He knows it wants him to kill. He knows that it will cause him to relapse in time. He's made peace with that knowledge, choosing to go down swinging when that time should come. It's all part of his acceptance that the Mark of Cain is indeed a terminal illness.
And yet, Dean had some hope that Cain might know something he doesn't---that there was a cure.
Dean holds the Blade tight, making his move to attack. It is clear that Cain is the stronger of the two. He's borne the Mark for far longer, harnessed its dark powers---all at deep cost---and uses his demonic strength to push Dean back. Each time Dean tries to land a blow that will allow him to make the kill, Cain absorbs it and deals it back sevenfold.
Once he manages to toss Dean aside, smashing him through a window and stunning him, Cain can get what he wants most: the Blade. In the moment he picks it up again, Cain is transformed into the Father of Murder completely. He is holding the weapon that he used to slay his brother, and now he is making his move to kill Dean, the man he also infected with his curse.
Cain picks Dean up by his throat, choking him. The Mark has been wanting Dean's attention---and silence---for some time. Cain's choking of Dean accomplishes that. While Dean can rasp some words out, he's mostly silent, forced to finally hear what the Mark wants most. Cain tosses Dean aside again, telling him, “Has it ever occurred to you? Have you never mused upon the fact that you are living my life in reverse. My story began when I killed my brother, and that's where your story will inevitably end.”
Dean stares up at Cain in horror, realizing the bald truth being laid before him. The Mark of Cain has always wanted one thing: blood. Until now, that's been a general thing. It's taken any and all blood it can get. It mattered not if it were monster, human, friend or foe. The Mark would relish in all of it. But as Cain, the very mouthpiece for the Mark, continues, it lays out explicitly what it wants---and makes sure to make each potential murder land with the force of a physical blow.
The Father of Murder tells Dean, “It's called the Mark of Cain for a reason! First, first you'd kill Crowley -- there'd be some strange mixed feelings on that one, but you'd have your reason, get it done, no remorse. And then you'd kill the angel Castiel, now that one, that I suspect would hurt something awful. And then! Then would come the murder you'd never survive, the one that would finally turn you into as a much of a savage as it did me...your brother, Sam. ”
Sam. The Mark of Cain wants Dean to repeat the first murder. It wants him to do nothing more than kill his brother. It's what it's always wanted and that bald truth scares Dean more than anything. He protests, telling the Father of Murder, “No. Never.”
Cain, unable to take that answer as truth, puts the Blade at Dean's throat, and tells him, “The only thing standing between you and that destiny is this blade. You're welcome my son.”
Just as it looks as Cain will deliver the killing strike, raising the Blade high and preparing to plunge it into Dean's chest, he's stunned by Dean's quick thinking. Cain had a knife stashed at his side, a substitute for the Blade he hadn't yet reclaimed, and so it gives the elder Winchester an opportunity to stop Cain before it is too late. Dean pulls on its handle, sliding it free to slice through Cain's arm, severing his hand with the swift motion.
This action is the first symbolic one that Dean will take. Dean has always done everything he can to save his brother. After his father told him that he'd have to choose between saving and killing Sam, Dean always chose saving. He refused to even indulge the other concept. Any opportunity that arose to save Sam---be it from the demon blood, dying in his arms, or being Soulless---Dean took it and grasped it tight. For Dean, he would much rather cut his own hand off than kill Sam---and here he's cut Cain's hand off to symbolize it. It only happens after Cain tells him he will kill Sam---it only happens when the Mark spells out explicitly that it wants his brother's blood.
Stunned, Cain falls to his knees, clutching the stump of his arm. He's been defeated, unable to hold the Blade in the hand once attached to the Mark. All that's left is to face Dean and his own impending execution.
Dean, still resisting this moment, begs Cain to not make him do this. He can't go through with this. He knows that killing Cain will only infect him further. It will make the disease growing inside him all the worse. And so, pleading with not only Cain but the Mark itself, Dean begs him, “Tell me I don't have to do this---tell me that you'll stop---tell me that you can stop.”
Cain, as the Mark personified, puts the nail in the coffin of Dean's hope when he tells him, “I will never stop.” Cain may be telling Dean that he, as a demon, will never stop culling the people he's put on his list, but in reality, this is the Mark speaking directly to Dean. It is telling him, no matter what he does, no matter what resistance he puts up, no matter how hard he fights, it will never stop. It will always find a way to make Dean into a demonic monster and a slave to its blood lust.
And yet, as we see Dean raise the Blade high over his head and slam it down into Cain's back---to a sound of thunder---it is as if Dean is also killing the Mark symbolically. He cut off Cain's hand to symbolize his own when faced with killing Sam, and now he's killing the personification of the very disease polluting him. While this may create more turmoil in the short term for the elder Winchester, there is no doubt that this moment is a moment of triumph, too. He has been able to best the Mark by besting Cain. It is a glimmer of hope that he may be able to win.
While Cain may be the personification of the Mark itself, he's also Dean's advocate in this fight. The Mark may spell out precisely what it wants from Dean, it may give him the details its hidden until now, but there's also another side to what Cain says here. He's not just ruffling Dean's feathers to get a rise. He's not simply telling him his ultimate nightmare to punish him. He's giving him a gift, too. He's telling Dean what he is up against and why it is important that he fight.
Cain may tell Dean that he's going to kill everyone he knows. He may tell him that there is only “remission and relapse,” but underneath it all, Cain is begging Dean to do what he couldn't. Cain wasn't able to save himself. He had been infected for far too long, had given into it far too often, and become so twisted by its demands that he could no longer resist. He was overcome with it the moment he made his first kill post Colette---and he was overwhelmed by the Mark's hum when he grasped the Blade for the first time in over a century. It's all in his statement, “It's been too long. That old feeling, makes me wonder how I ever had the strength to resist.”
But it's more than watching Cain completely fall to the disease that matters here. It's what he's not saying that has weight. He's spelling out all the bad that will come, all the evil Dean will inevitably do, and all the pain that is sure to come from this terminal disease. It will only cause Dean to suffer---which is why he wants to offer Dean an out through death. In reality, however, he's also giving Dean a blueprint to fight back.
Cain knows where he went wrong. He knows the mistakes he made in succumbing to the Mark---and as he taunts Dean for holding back, there's almost a sense of awe coming from him. Cain is amazed that Dean can hold back while holding the Blade, while engaged in combat---mortal at that---and he is almost pleased that Dean can. It's a hopeful moment because it means that Dean may be able to do what Cain couldn't, after all: win against the Mark.
While the Mark may speak through Cain, telling him that he will inevitably kill Sam, Cain's also tapping into Dean's old familiar mantra to save Sam at all costs---and to never ever follow through on the kill command. This is unintentional. Cain, so far gone in his fall to the disease, doesn't quite understand that Sam is not the liability or the victim he paints him to be. Instead, Sam is Dean's greatest strength. It is only because of Sam that Dean has made it this far.
When Cain killed Abel, his brother was removed from the story. He was a passive being that had found death on the end of the First Blade as the first murder. He couldn't speak anymore after that. There was no way for him to confront Cain for what he had done. There was no way for him to stand up to him. Cain had killed him and he had disappeared. His only presence in Cain's life was to be the ghost that chased him down through the centuries---the guilt that the Father of Murder could never quite shake.
Sam, on the other hand, is very much alive. He's also been the very reason that Dean became human again. If not for him, Dean would have become another Knight of Hell, eternally killing everyone and anyone that got near him. He would have fed its addiction with pleasure. But, because Sam managed to use their knowledge about a cure, he was able to help Dean reclaim his humanity. He was able to help Dean remember who he is and not what he had become. Sam gave this to Dean. Sam gave Dean a second chance to stand up to the Mark.
Since then, he's been Dean's biggest supporter, care giver, and advocate. He's the one that watched his brother closely, making sure to get in the killing blows to prevent his brother from reigniting the Mark so soon after the cure. He's the one that supported his brother's choice in resuming hunting to make amends---after all, he understood that after what happened upon killing Lilith. Sam's the one that made sure to keep an eye on his brother after Dean killed Olivia. Sam has been the one to call Dean back to himself at every turn---after Dean killed Abaddon and after Dean nearly killed Metatron. He's the one that pulled Dean from his funk after he beat on Dark Charlie---getting him to go and help on a hunt and remember what it means to commit to the family business of “saving people, hunting things.”
While Sam didn't like Dean's statement about giving up on finding a cure, he supported that, too.
He knows that his brother will fight hard against the Mark, and now that they're facing the actual moment that his brother will have to use the Blade on Cain, he knows he'll have to fight even harder for his brother. Sam knows that they must do this, and as they discuss the means and methods, before Dean can even say it, he says “The Blade.” It's resigned, knowing that they have no choice. It's quiet, too, showing that not only does he understand in order to save innocents, he understands that Dean must do this to face his disease head on.
As Dean honestly expresses to him that he must do this alone, Sam accepts this, too. It is his acceptance, support, and patience that has made all the difference to Dean. Unlike Abel, Sam isn't passive. He's not silent. He's not invisible. Sam has the ability to speak up for Dean. He will stand as a solid reminder of Dean's humanity. While Cain may see Sam as a victim, someone destined to find his death on the end of the Blade, Sam is proving that he's more than that. He's the key to Dean's success.
This is most apparent after Dean emerges from the barn, stumbling weary, broken, and changed by the Mark, Blade, and the killing of Cain. Dean sounds rough when he speaks, looks like he's teetering on his feet, and is emotionally raw. Anything could flip the switch in his head---could trigger the disease to overcome him. In many ways, Dean's emergence from this room must be what it's like to come back from a medical test that leaves one feeling far worse than before.
Dean, showing yet another feat of strength, hands the Blade over. Instead of handing it to Crowley---the one who had been keeping it---Dean hands it to Castiel. While Sam may be his support, he is too close to the situation---too close to Dean physically---for him to hold onto it and keep Dean away from it safely. Castiel is the logical choice. He won't use it as leverage, he'll keep it well hidden so if Dean should fall to the Mark's disease he won't be able to find it, and he'll keep others from finding it to dangle as a carrot.
Yet, this act seems to be where Dean's strength ends. He turns to a stunned and emotional Sam, collapsing into his brother's welcoming and strong arms. Sam, ready to catch him, pulls him close and praises, “You did it. Dean, you did it.” Sam is salving the wounds he incurred in that room, giving Dean the very thing he needs in this moment. Cradled in Sam's arms, Dean can recenter himself, start to recover from his experience, and be assured in his brother's support and love.
Without Sam waiting to catch him, it's possible that Dean would have succumbed to the Mark ages ago. Without Sam waiting outside that door, Dean would have gladly taken Cain's offer. Without Sam, after Dean killed Cain, it's possible the monster he feared would have emerged yet again. It's the knowledge that Sam was waiting for him that saved Dean here. It was the knowledge that Sam would catch him when he fell that allowed him to hold onto his sanity long enough to get through the ordeal of killing Cain---and symbolically killing the Mark itself.
As they end up back at the Bunker, Dean is still shaky, barely holding on. He keeps his focus not on Castiel, but on his brother. It is as if this reassurance that Sam is there---alive---is what will keep him going. He will also take solace in Sam's words, finding strength he doesn't have in them. Sam tells him, “What you did back there, it was incredible. You know, if you can do that without losing yourself, that's cause for hope---even without a cure.”
Now that Dean knows what the Mark wants, knows what it will try and make him do, he fully knows what the stakes are. His demonic self had once tried to kill Sam---will the Mark try and make him do so again?
Or will he find his salvation in Sam?
As he goes to rest, Sam tells Castiel, “Dean's in trouble.”
Tuned to his brother's emotions, needs, and struggles this season more than ever before, Sam knows that their fight has only begun. Dean managed to get through this, he managed to wield the Blade and use it to stop Cain, and he may have been able to hand the Blade over afterwards, but what of the next time? What will happen the next time the Mark pulls on Dean?
In the aftermath of this traumatic event, Sam can see just how fragile his brother truly is---how vulnerable. He knows Dean is strong. He knows his brother can get through this---and he meant every word he said to Dean---but he knows they're a long way from succeeding. His brother is barely holding on right now. If they are faced with another situation like this too soon, Sam fears that Dean might not be able to fight back hard enough---to hold up as well.
It will mean that Sam will have be ever more vigilant, watching and supporting his brother to keep him whole, to fight for his humanity---and to fight for their brotherhood against the Mark's dark disease.
If anything, unlike Cain, Dean will not have to face this disease alone. He'll have his brother, Sam, and that's why he'll win in the end.
Where else in the episode do you see disease discussed?