"I didn't chose this life, Dean. It was forced on me. I don't want to spend the rest of my life in Purgatory. I wanna live, I wanna be free. I wanna be like you."
-- Ophiel begs to Dean to help him escape.
Ophiel is a powerful angel/demon hybrid known as an Unbidden, and the last of his kind in existence. The angels waged a war of genocide on the Unbidden, wiping them all out and declaring it a crime for an angel to produce offspring with a demon. One survived, Ophiel, and was chosen by God to guard the door to Purgatory, until being freed by Dean Winchester.