The Mark of Cain is the source of The First Blade's power. It is one half of the weapon that Cain used against the rest of the Knights of Hell. Cain later transferred the Mark to Dean, so that the hunter could kill Abaddon.
When Dean used the First Blade for the first time, he felt a murderous rage that did not dissipate after he killed a victim with it. It later gave him immunity to Abaddon's powers and telekinesis and have a telekinetic control of the blade, all with great concentration, allowing him to overcome and kill her. After killing Abaddon, this rage caused him to mutilate her corpse. He also displayed superhuman strength while fighting a vampire. Dean later showed precognition, receiving a nightmare about a slaughter he would later commit under the Mark's influence. When a human with the Mark refuses to give into its rage, it seems to keep them from being able to access its other abilities as when Dean fought Cain and didn't give into the Mark's rage, he displayed no extraordinary abilities which Cain noted. However, though mostly due to the devil's trap Cain was confined in that bound most of his powers, Dean proved capable of defeating Cain even without the Mark's abilities while Cain with the Mark's abilities couldn't defeat him.
When the bearer of the Mark receives a mortal wound that would kill them, the Mark transforms their soul into a Knight of Hell, so that it can live on, and never perish. It is also revealed that if the bearer does not satisfy the mark, by killing, it will slowly but steadily turn them into a demon (presumably to make them willing to kill). Castiel explains that the grip of the mark affects the bearer on more than just a purely physical level, and that cutting it off or even burning it off wouldn't work and it would require a source of great power. According to Metatron, there is a way to remove it and it requires the First Blade to work. Conversely, Cain himself claims there is no cure, however, seeing as an angel Metatron's older than Cain and is the scribe of God, it's interesting that Cain's response contradicts Metatron's though its possible Cain merely believed that after so long of being forced to bear the Mark.
Effects of the MarkEdit
The Mark imbues its bearer with several powers as well as psycho-supernatural burdens which eat away at the bearer's character.
- Super Strength - The Mark grants the bearer enough augmented strength to overpower a lower vampire and shrug out of a lesser angel's hold. Dean was able to easily massacre a whole room full of grown, strong men, and emerge seemingly unharmed. Dean was able to effortlessly hoist Abaddon into the air while stabbing her with the Blade.
- Murderous Rage - The Mark affects the bearer to where they constantly must kill something, if they don't they'll eventually die as pointed out by Crowley. However, as demonstrated by Cain, this could be fought and Sam suggests that the bearer must want to at a conscious level for it to work. Metatron states that each time the bearer gives into the Mark's rage, they fall more and more under its power. After giving in to its power once more, Cain felt that it was better to let the Mark control his actions and not fight it.
- Telekinesis - The Mark grants the bearer the ability to summon the Blade to the hand that calls it.
- Resurrection - The Mark, if the wearer dies, will resuscitate the bearer back to life as a demon, more specifically a Knight of Hell. This can be reversed through the Demon Curing Ritual though the wielder will still retain the Mark even after being rendered human again. However, Cain indicated that if one wielder of the Mark killed the other with the First Blade they wouldn't come back as he seemed to think his killing Dean would be permanent. He also seemed to believe Dean killing him would be permanent too.
- Immunity - The Mark allows the wearer immunity to demonic powers, as shown by Dean resisting Abaddon's telekinesis. It also granted Dean great resistance to the Demon Curing Ritual, causing him to retain demonic mannerisms long into the ritual even when he was made human enough to be immune to a devil's trap. However, the Mark did not make him completely immune and he was eventually cured. It also doesn't grant immunity to spells as the Transfiguration Spell still affected Dean.
- Super Stamina - The Mark greatly enhances the bearers stamina. Dean was able to go without sleep and food for several days with no ill effects.
- Precognition - Dean had a nightmare that showed him in a room having slaughtered a group of men. It later came true.
- This Mark was given to Cain by Lucifer. There are only three possible scenarios in which Cain could receive this Mark; either Lucifer touched him using a vessel, or in his true form somehow, was able to brand it as if he were casting a spell and the Mark formed itself.
- The Mark of Cain can only be worn by someone worthy, as explained by Cain. The conditions required to be considered such are unknown although Cain stated that Dean is very similar to him as both brothers sacrificed themselves in order to save Sam and Abel respectively. Dean inquired as to whether he needed to be a killer like Cain, to which he replied he did, meaning that the Mark can only be worn by people who have killed, as well as other requirements.
- It is quite possible, that if the bearer of the Mark concentrates and wills enough, they could become immune to demonic powers, as Dean Winchester was able to fight and become immune to Abaddon's telekinesis during their brief fight, though the Mark glowed red with power so it could just be temporary effect.
- Because Lucifer's powers are the source of the Mark, this could be the reason that when a bearer of the Mark dies they are resurrected as a demon as stated Lucifer is the father and creator of demons.
- Though Dean is now human again, he still retains the Mark which as Castiel points out, will become a problem in the future. He also still possesses the potential to become a demon once more as the Mark will turn him into one if he dies again.
- It is confirmed that the Mark's effects still affect Dean after him being cured of being a demon, as he still had to deal with the Murderous Rage, shown by his mass-murder of a group of people. He also displays a new ability not previously shown: precognition. He gets a nightmare of a slaughter he later commits under the Mark's influence.
- It seems that the Mark is so mysterious that even the Men of Letters don't have any record about it.
- According to Sam, Cain didn't really transfer the Mark to Dean as copy it as Sam states that Cain still possesses it.
- In The Things We Left Behind, Dean fell under the Mark's influence and went into a murderous rage without The First Blade and slaughtered six people.
- In The Hunter Games, the Mark glowed without being in the presences of The First Blade which drove Dean into another murderous rage; nearing killing Metatron while torturing him.
- In About a Boy, Dean loses the Mark while turned to the age of 14 again as he didn't have it then. The Mark returns when he returns to his proper age.
- As of The Executioner's Song, Dean is the only bearer of the Mark after killing Cain. It is also indicated that if one bearer of the Mark kills another with the First Blade, they won't come back as Cain didn't seem to think Dean would come back if he killed him and Cain didn't come back when Dean killed him.
- In The Executioner's Song, Sam and Dean both felt that Dean giving into the Mark to kill Cain himself would likely cause him to lose control of himself completely. As a result, when Dean fought Cain, he didn't give into the Mark and displayed only normal human abilities. However, this proved enough for him to beat Cain, only calling on the Mark to power the First Blade so Cain could be killed and Dean retained his humanity.
- Season 9
- Season 10