On the show Supernatural Castiel is an angel of the lord sent down to Earth for various missions. Although he is an angel in his own words he is "a poor excuse for one"
After Sam has tricked Castiel into helping him find Crowley, Castiel, along with Meg and Dean, hunt for Crowley's whereabouts at the Campbell compound. Over there, Dean and Castiel argue whether it is safe to return Sam's soul. Castiel states that Sam might turn up worse since his soul has been stuck in the cage with Lucifer and Michael. Then, Castiel and his group run into a pack of Hell Hounds. Meg kisses Castiel in order to steal Castiel's Angel Blade, but she gets overwhelmed by Castiel who kisses her back. When Meg asks Castiel where he learn how to kiss like that, Castiel replies he got it from the pizza man.
At first, Castiel is an emotionless soldier who worked within his role. As he interacts with Dean and Sam, he begins to question his orders.