Castiel is an angel of the Lord who was ordered to pull Dean Winchester out of Hell and help him with his mission to stop Lilith from breaking the 66 Seals that would release Lucifer. He seems to be very mysterious and introspective about his assignment from God. When Lucifer was released form his cage, Castiel rebelled against Heaven to help Sam and Dean to kill Lucifer. When they succeeded to put Michael and Lucifer in the cage, Castiel returned to Heaven where he found himself in the middle of a Civil War because he broke the natural order. Ever since then he's been trying to defeat Raphael and help the Winchester to get Sam's soul back from the pit. Read more...