They explain what happened and Crowley tells them that the weapon Ramiel used was the Lance of Michael which he gave Ramiel six years ago after Lucifer's defeat. Dean asks Castiel about his plans.
Dean reminds him that he has had success with stronger adversaries.
After Dean leaves with Crowley to find a way to defeat Abaddon, Castiel also leaves to begin a search for Metatron and Gadreel while being pursued by other angels and eventually kills rebel leader Bartholomew and assumes command of his faction but a deception of Metatron's makes him lose his army but instead teamed up with angels Gadreel and Hannah to infiltrate Heaven and destroy the angel tablet, cutting off Metatron's power to allow Dean to kill him. Anna comes to Dean in a dream, telling him that she has been held prisoner in heaven after being turned in by Castiel, but has escaped. Crowley tempts him with one more offer: 50,000 souls from Hell to use in facing Raphael. As he eats the hamburgers, Castiel announces that Famine is in town and is causing the strange, starved behavior among the victims. In his human mindset, he had no idea of what he was capable of and was nervous with the idea of using his powers to kill demons when he had no idea how. After Maggie is brutally murdered, Castiel joins the investigation which points to a boy named Nate that she has a crush on. At the portal to Heaven, Castiel meets with Dumah, who reveals that the angels don't have Jack.
It can be overwhelming to humans and so can my real voice.\" However, Castiel stated certain, \"special people\" are able to tolerate his true appearanc… Eventually, Dean manages to decapitate the monster and store the head in the Impala's cooler while explaining to Castiel what happened. Ishim grabs Castiel by the collar and continues punching him.
As they continue researching, Castiel collapses in a seizure-like fit.
Finally, Metatron tells Castiel what he knows about the Darkness: that she's God's sister whom God sacrificed to make the world. He snaps the Lance in two and its destruction saves Castiel's life. Castiel digs through a garbage can for food and meets waitress April Kelly who gives him a sandwich. After an awkward (and amusing) conversation with the sheriff, they discover that Raphael's vessel has been taken to a local hospital. He follows one, trying to find out why they are there and is captured by Lucifer, who imprisons Cas in a ring of flaming holy oil. After Mick and Ketch depart, the reaper, Billie, arrives and reveals that Sam and Dean made a deal to facilitate their escape, the cost of which was that at midnight, a Winchester would have to die, and breaking the deal would come with consequences on a cosmic scale.
Castiel, sounding uncertain, says he will heal himself when his works are complete. Castiel meets with Crowley, who has assembled the necessary ingredients.
As Castiel is obviously suffering, Sam and Dean agree that foremost they need to find Rowena and remove the spell Castiel is under. However, as the Winchesters and Castiel start to get overwhelmed, Castiel grabs Jack's corpse and leads them into a nearby crypt for safety where they discuss options. He does, however, become close friends with the brothers, who encourage him to be kinder, more caring and more selfless. Castiel explains his reasoning for going off on his own, telling Dean he needed a win for himself after everything that has happened in the past year and his failures.
Castiel manages to kill his assailants, and turns back to the figure struggling out of the ground. Dean embraces him, but Castiel is not happy to have been found by Dean. Using the Plan B, the group is able to trap the ghost in a salt circle, revealing him to be a young boy, to Castiel's shock. Castiel replies that they can't risk it. Balthazar and Castiel vanish. Dean and Bobby stand him up. Castiel orders Balthazar, who has snuck up behind Atropos with a knife, to stop. It was his job to help prevent Lilith from breaking the 66 Seals that, once broken, would release Lucifer from his cage in Hell. He then reveals himself as Lucifer to Rowena and Crowley. As the energy courses through his body, he is able to block Dagon's attack, and with her arm in his hand he incinerates her, killing her.
Castiel is surprised at the partnership with their differing goals, but both seem to think they have taken the best course available.
Status The four soon learn of Roseleen Greenfield cutting herself for Vince/Lucifer and head to the hospital, where Castiel is told by the Winchesters to wait with Crowley while they question Greenfield. With that information Crowley threatens to reverse it, but is stopped by Castiel. Castiel is restored when Jesse leaves and goes into hiding. Sometime later in a forest, Ketch formally introduces himself to the trio, asking Castiel to sense if he is lying to them. Back in the present, Sam reveals to Dean that "Castiel" is actually Lucifer. Later, when Sam and Dean are driving back to the Bunker in the Impala, a wounded Castiel appears on the road in front of them, asking for help. Castiel takes the opportunity to ask Sam a few questions. Dean and Castiel confront Gail outside and while Castiel initially wants to use force to get the bow, Dean convinces him to talk to Gail instead. At the farm, Castiel searches the barn and finds Amelia and a few other victims. Crowley gets up, pats Cas on the shoulder in a strangely reassuring fashion, and leaves Cas glaring after him. Upon regaining his memories, Dean gave him back his trench coat, but he still wore Emmanuel's clothes until he became insane.
Dean tries to apologize face to face, but Castiel says he doesn't have to, having received his prayer. Raphael appears and beats Castiel mercilessly, throwing him down a flight of stairs. Castiel awakens in the mental hospital as Sam and Dean uncover the Word. Fooled, Castiel appears to Sam and asks where it is, but is met with hostility and derision because he is unaware that Sam was referencing Raiders of the Lost Ark.
Even after Castiel was free from the spell, it still has also apparently "scarred" Castiel so deep that Cass wouldn't even leave the bunker. Initially following his rescue from Purgatory, Castiel appeared weakened from his time in the monster realm as he is quickly drained from using his powers such as teleporting or killing a low-level demon.  While on vacation, almost two years after his last known attempted solo case, Castiel proved himself to have grown into a skilled hunter in his own right, able to interact effectively with law enforcement on his own, go through case files, determine what type of monster he was dealing with, figure out its pattern and determine a possible location for its lair all without help from the Winchesters or other hunters.
Suddenly Castiel returns, possessing Jimmy's daughter Claire Novak. While Castiel's followers thus abandon him, Gadreel is convinced to side with Castiel, although Dean attacks Gadreel when he attempts to explain the situation to them. Dean wakes in the morning to find that Zachariah has zapped him five years into the future, into 2014. He insists that the demon not harm Lisa and Ben, but Crowley refuses to make such a promise.
Angered, he attacks Dean and throws him against a wall, but Sam manages to draw an angel banishing sigil that blasts Lucifer out of the Bunker.
Cutting his forearm, Cas draws a sigil on the wall in blood.
Samuel comes around and tells them where they can find the demonic prison housing the monsters, though he refuses to take part in the attempt on Crowley. Dean punches the mirror and trashes the motel room. Castiel is angered to see Naomi after all she did the last time they met, but Naomi reveals to him that there are less than a dozen angels left alive and they will soon burn out if something doesn't change. Castiel was also reunited with his brother Gabriel who wanted no part in the conflict as Castiel set out to locate him to get him to help in restoring Heaven. He finds Metatron filming a dying man, and while Metatron cheerfully explains that he can't help, Castiel arrives and heals the man instead. Castiel and Uriel appear and demand that Sam and Dean hand over Anna, with Castiel announcing, "We're here for Anna...she has to die." Castiel goes to Dean, and watches invisibly as he rakes leaves. Sam is certain that the angel will not appear, because Sam has prayed to Castiel several times since he escaped Lucifer's Cage a year ago without receiving an answer. He works to support the efforts of Sam, Dean and Bobby in stopping the battle between Michael and Lucifer.
At this moment Castiel shows up to help, having taken a bus to this location. Kelvin assures him it will be enough as they only need one for Dagon and one for Kelly. Anna approaches him, explaining that she felt doubt before she left Heaven. As they drive off, Castiel replies that he wasn't told anything, rather he was shown the future. The next morning, Dean and Castiel place Raphael's vessel in a circle of holy oil in his room at the hospital. At first Crowley continues to believe Castiel is bluffing, but realizing that he is serious, tries to escape with the Word of God. The angel relents, and goes with them. His lack of emotion and understanding of human behavior such as sarcasm has led to several humorous situations throughout the show, and has occasionally gotten him into trouble with humans, ultimately leaving Dean or Sam to amend the situation. Afterwards, Dean informs Castiel of Gabriel's death and reassures him that Sam took care of Lucifer, having stranded the archangel in Apocalypse World. At first, unwilling to believe, Castiel suggests that maybe Joshua was lying. With his powers he is able to defeat Famine, but is then locked in Bobby's Panic Room by Dean and Castiel. Castiel's powers change over time for a number of reasons, such as when he is disenfranchised by Heaven in season five and when the angels are expelled from Heaven by Metatron. Soon after Castiel receives a call from Dean and learns that they are in Rocky Mountain National Park in Colorado. Castiel insists that they must find the angel and the other pieces of the Staff. Despite this, he does not display the blank apathy or mocking superiority that seem to characterize angels such as Uriel or Lucifer. Cas tells Dean that he will return, but that Dean will have time to talk to Sam. Naomi explains that the angels rescued Castiel from Purgatory, though it cost many their lives and asks what the Winchesters are up to. Dumah is unrepentant, but refuses to let Castiel leave with Jack.
He prays to Castiel while Dean is away. He also recognizes Ezekiel when Dean mentions he is there to help Sam and tells him that Ezekiel can help.