Castiel is a character who for a long time remained behind the scenes of the events surrounding the Winchester brothers, but who also had a direct hand in some of the events. Later it turns out that he is an angel, who, according to him, fulfills the personal will of the Lord. Castiel has been assigned to Earth’s horizon as the one who will see to it that order on Earth is maintained. And it was thanks to the angel’s help on behalf of God himself that Dean was able to become a normal earth again: Castiel pulled him straight out of Hell, saved him from the eternal nightmare that had unfolded around Winchester.
When it comes to appearances in the series, only the mention of the angel can be heard for the first time during the third season in the episode titled “The Scarlet Dawn”: Sam casts a spell, the text of which includes the name belonging to the servant of God. You see Castiel in person right at the beginning of season four, in the very first episode called “Lazarus Resurrection,” after Dean returns from the abysses of Hell and then tries to convince his family that it is really him. Since Dean does not remember how he was saved, the main characters decide to find out who was so “kind” to take on such an obviously impossible job for most living and non-living creatures. As a result, instead of a possible enemy, as they assumed, they got a capable ally, and for the audience – another main character.
In the course of the further plot Castiel appears more than once more, his presence will be observed throughout most of the series. In the next fifth and sixth seasons the character appears with regular frequency, in the seventh and eighth only in periods, and with the release of the ninth season – on a constant basis until the very end of the series, until the last season 15. However, Castiel is not always himself in fact. For example, at the time of season 11, the angel ceases to be one, while for most of the season he is the incarnate Lucifer.
More than once throughout the series, after his debut appearance, Castiel will “die” and “rise again. In different time periods: for example, it happens at the very beginning of the seventh season, after which his fate remains unchanged for a long time, so that towards the end of the season Castiel, who had lost his memory and considered himself an ordinary man, reappears. However, after that, thanks to a meeting with Dean and a battle with demons, the angel remembers everything and feels guilty. He then takes the insanity of Sam in a mental hospital upon himself, loses his memory again and goes insane himself, staying in an asylum instead of Sam. In season nine, Castiel is killed again, but resurrected by another angel.
The character’s most recent appearance is a moment in season 15 episode 18 called “Despair.” Castiel and Dean find themselves locked in a bunker when Death literally knocks on the door. The elder of the Winchesters is supposed to die, but the angel once again decides to do things his own way. There was a heartwarming goodbye conversation between him and Dean, after which Castiel made a deal with the Void that ended up taking both him and Death himself, leaving Dean alive. However, at the very end of the season, it is said that Jack was able to bring the angel back to heaven.
“Lazarus Rising” (Season 4 Episode 1) marks the first appearance of Castiel.