Changes

For six weeks after Dean disappears, Sam searches for his brother without success, capturing and torturing the [[Crossroads Demon]] [[Dar]] for information after tricking [[Lester Morris]] into summoning her.<ref name="ten01">[[10.01 Black]]</ref><ref name="ten03" /> At the same time, Dean, now a [[Knight of Hell]] himself,<ref name="ten05" /> and Crowley hit the road, partying with each other. Although Crowley expresses interest in Dean ruling Hell at his side, Dean refuses. To sate the [[Mark of Cain]]'s bloodlust, Crowley sends surviving Abaddon loyalists to attack Dean , who easily dispatches them.<ref name="ten01" /> Crowley also sends Dean to fulfill Lester's deal, but Dean kills Lester instead. With Dean proving to be too uncontrollable even for Crowley, Crowley makes a deal with Sam to help Sam capture Dean in exchange for the First Blade. Sam is able to capture Dean<ref name="ten02">[[10.02 Reichenbach]]</ref> and attempts to perform the [[demon cure]] upon his brother. Though Dean breaks free, he is restrained by Castiel who was himself rescued by Crowley from an attack by [[Adina]]. Sam is able to complete the cure and turn Dean human again, though he retains the Mark of Cain.<ref name="ten03" />

Having regained control of Hell, Crowley executes surviving Abaddon loyalists, though his alliance with Dean and method of ruling leads one dissatisfied demon to commit suicide.<ref name="ten03" /> Due to soul numbers being down following the war with Abaddon, [[Raul]], [[Gerald]] , and another demon open a brothel where patrons sell their souls in exchange for the services of the kidnapped prostitutes. After meeting Shaylene, one of the prostitutes, the Winchesters learn of the operation and attempt to shut it down. However, the [[witch]] [[Rowena MacLeod]] finds the brothel first and kills Raul, causing Gerald to flee. Though disgusted by the operation, Crowley dispatches demons to capture Rowena and kill the surviving prostitutes who are recruited by Rowena to form a coven. The demon assassins are killed by the Winchesters, saving one of the rescued prostitutes, but a second team is able to capture Rowena thanks to the intervention of [[Cole Trenton]]. Crowley is shocked to recognize Rowena as his long-absent mother,<ref name="ten07" /> something that she subsequently uses to manipulate Crowley.<ref name="ten09">[[10.09 The Things We Left Behind]]</ref><ref name="ten10">[[10.10 The Hunter Games]]</ref><ref name="ten14" /> In particular, Crowley has his demons capture [[Olivette]], High Priestess of the [[Grand Coven]] , so that Rowena can petition to freely perform magic again.<ref name="ten16">[[10.16 Paint It Black]]</ref> Following a failed attempt attempts by Rowena to directly assassinate Dean and then to have Crowley do it, Crowley kicks Rowena out for her attempts to manipulate him.<ref name="ten17">[[10.17 Inside Man]]</ref>

During this time, the Winchesters and Castiel search for [[Cain]] in hopes that he will know a cure for the Mark of Cain. Having been driven back under the Mark's influence by killing Abaddon's demons, Cain begins slaughtering all of his human descendants to get rid of his "cursed" bloodline. The discovery of this by Castiel causes the Winchesters, Castiel , and Crowley to team up together to stop Cain once and for all. Using magic from Rowena, they are able to lure Cain into a [[devil's trap]], reducing his powers to the point that Dean can fight him. Though initially outmatched as he is unwilling to give into the Mark of Cain's power and rage, Dean manages to gain the upper hand and kills Cain with the First Blade. However, he hands the First Blade over to Castiel instead of keeping his promise to return it to Crowley, damaging Crowley's trust in Sam and Dean.<ref name="ten14" />

Enraged by Crowley kicking her out on the street,<ref name="ten17" /> Rowena demands that Sam kill Crowley in exchange for her help in decoding the ''[[Book of the Damned]]'' and getting a cure for Dean and the Mark of Cain , and Sam agrees to the deal.<ref name="ten19">[[10.19 The Werther Project]]</ref> After [[Charlie Bradbury]] comes up with a way to read the ''Book of the Damned'', Rowena demands that Sam uphold their end of the deal before she will cure Dean. Sam is able to lure Crowley into a trap and immobilize him with a [[devil's trap bullet]], but Sam's attempt to kill Crowley with a spell provided by Rowena fails. Instead, Crowley, who has been trying to reshape Hell for the better, is reminded of his evil nature and revels in reembracing it.<ref name="ten22">[[10.22 The Prisoner]]</ref> Despite this, Castiel is able to enlist Crowley's help in getting the ingredients needed for the spell to remove the Mark of Cain. However, after performing the spell, Rowena escapes and uses the Attack Dog Spell to force Castiel to kill Crowley.<ref name="ten23">[[10.23 Brother's Keeper]]</ref> Crowley escapes death by fleeing his [[meatsuit]] and then calling in demons to secure it once Castiel has left. Upon returning to his usual body, Crowley is informed by [[Jervis]] and another demon that either [[Michael]], or [[Lucifer]] , or both , rattled the Cage, putting Hell into an uproar because of the belief that one or both of the archangels is trying to warn them about [[the Darkness]].<ref name="eleven01">[[11.01 Out of the Darkness, Into the Fire]]</ref>

Following the death of Crowley, the last [[Prince of Hell]] [[Asmodeus]] takes control of Hell, proclaiming that he will return it to the old days of fire and brimstone.<ref name="thirteen02" /> Under Asmodeus' leadership, the demons actively hunt for the [[Nephilim]] [[Jack Kline]] and take Lucifer captive, though he later escapes with the aid of Castiel. Hell also begins preparing for a possible upcoming invasion by the [[Apocalypse World]] [[Michael (Apocalypse World)|Michael]].<ref name="thirteen07">[[13.07 War of the Worlds]]</ref><ref name="thirteen12" /> However, not all demons are willing to bow to Asmodeus' s will and the [[Crossroads Demon]] [[Barthamus]] makes a deal with Sam and Dean to exchange a [[Nephilim]] -tracking spell for their help in retrieving his human bones from [[Luther Shrike]]. Though they get the bones with the help of [[Alice]] and the demon [[Grab]], Grab is killed by Luther , who reveals the truth about his history with Barthamus to the Winchesters. Disgusted, Sam and Dean refuse to complete the deal and Barthamus, who was also sought by Asmodeus for his rogue actions, is killed when Alice burns Barthamus' human bones.<ref name="thirteen08" />

Though Asmodeus is able to capture and imprison both Castiel and Lucifer, wanting to keep power for himself<ref name="thirteen07" /> , the two angels are able to escape by briefly working together, killing several of Asmodeus' demons as they leave. However, their brief alliance falls apart afterwards.<ref name="thirteen12" /> During this time, Asmodeus is able to get his hands on the [[archangel blade]], the one weapon that can kill an archangel such as Lucifer or Michael in the hands of another archangel. Asmodues Asmodeus is aided by the fact that he holds the archangel [[Gabriel]] captive<ref name="thirteen13">[[13.13 Devil's Bargain]]</ref> and feeds off of Gabriel's [[grace]] for more power. After Gabriel's rescue by [[Ketch]],<ref name="thirteen17" /> Asmodeus leads a demon incursion into [[the Bunker]] to retrieve his prisoner. However, Gabriel fights back and the archangel kills Asmodeus, leaving Hell leaderless once more.<ref name="thirteen18" />

[[Abaddon]] is an incredibly powerful black-eyed demon who is one of the first demons ever created, and a [[Knight of Hell]], part of an elite group of demons believed to have been destroyed by [[archangels]].<ref name="eight12" /> In fact, after she and the other Knights kidnapped [[Cain]]'s wife, he killed them himself, accidentally killing his wife while Abaddon possessed her.<ref name="nine11" /> In 1958, as part of her work for Hell, Abaddon brutally murders [[Father Max Thompson]] for developing the [[demon cure]].<ref name="eight22" /> Shortly thereafter, Abaddon attempts to create a "demon factory" by stealing people's [[soul]]s and transforming the souls into demons, but she is confronted by [[Men of Letters]] initiates [[Henry Winchester]] and [[Josie Sands]]. Seizing upon an opportunity, Abaddon possesses Josie to infiltrate the Men of Letters.<ref name="nine17" />

On the night of August 12, 1958, Abaddon slaughters the Men of Letters and follows Henry Winchester through time to get the key to [[the Bunker]], the greatest storehouse of supernatural knowledge that ever existed. Unable to kill Abaddon, Henry shoots the Knight in the head with a [[devil's trap bullet]], but not before she mortally wounds him. Dean tells Abaddon that as they can't kill her, he is going to cut her into pieces and bury them in concrete, trapping her forever.<ref name="eight12" /> She is later put back together by Sam and Dean in order to [[demon cure|cure her]] of being a demon as the third [[Trials|trial]] to close the [[Hell Gates|Gates of Hell]], but she escapes while they are distracted.<ref name="eight22" /> She later then attacks [[Crowley]] and Sam after Crowley calls for help after being captured, planning to take over ruling [[Hell]] herself. However, Sam douses her in [[holy oil]] and lights her up, forcing her to abandon [[Josie Sands]]' body and flee in her smoke form.<ref name="eight23" />

Days after her brief defeat, Abaddon has Josie's body restored and begins a crusade to take over Hell and Earth. She tries to kill Sam and Dean and get Crowley's location from them, but flees when [[Gadreel]] reveals himself nearby.<ref name="nine02" /> Abaddon then works to reshape Hell, using Crowley's absence to take over and reneging on all soul deals.<ref name="nine06" /> After being freed by the Winchesters,<ref name="nine10" /> Crowley starts a war against her, allying with Dean to find [[the First Blade]], the only weapon that can kill Abaddon.<ref name="nine11" /> After finding out about Crowley's search, Abaddon starts her own<ref name="nine16" /> and starts having her demons loyal to her steal innocent people's souls to build her own army of demons loyal only to her.<ref name="nine17" /> After attempting to lure the Winchesters into a trap with the help of Crowley, Abaddon was killed by Dean with [[the First Blade]] after the [[Mark of Cain]] made him immune to her powers,<ref name="nine21" /> allowing Crowley to subsequently regain control over Hell.<ref name="nine23" />